HETEROCYCLIC INHIBITORS OF THE SODIUM CHANNEL

Abstract

The invention relates to compounds useful in treating conditions associated with voltage-gated ion channel function, particularly conditions associated with sodium channel activity. More specifically, the invention concerns heterocyclic compounds (e.g., compounds according to any of Formulas (1)-(X) or Compounds (1)-(92) of Table 1) that are that are useful in treatment of conditions such as epilepsy, cancer, pain, migraine, Parkinson's Disease, mood disorders, schizophrenia, psychosis, tinnitus, amyotropic lateral sclerosis, glaucoma, ischaemia, spasticity disorders, obsessive compulsive disorder, restless leg syndrome and Tourette syndrome.

Claims

1. A compound of Formula I: ##STR00121## wherein R.sup.1 is H or optionally substituted C1-C6 alkyl; or R.sup.1 combines with R.sup.2 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.1 combines with Ar to form an optionally substituted bicyclic 9- to 10-membered heterocyclyl; R.sup.2 is H or optionally substituted C1-C6 alkyl, or R.sup.2 combines with R.sup.1 to form an optionally substituted 5- to 6-membered heterocyclyl; m is 0 or 1; n is 0 or 1; R.sup.3 is H, optionally substituted C1-C6 alkyl, or optionally substituted phenyl; or R.sup.3 combines with R.sup.1 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.3 combines with Ar to form an optionally substituted bicyclic 9- to 10-membered cycloalkyl or aryl group; and Ar is optionally substituted phenyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

2. A compound of claim 1, wherein the compound has the structure of Formula I(a): ##STR00122##

3. The compound of claim 1, wherein Ar is unsubstituted phenyl or Ar is phenyl having 1, 2, 3, 4, or 5 substituents selected independently from optionally substituted C1-C6 alkyl, optionally substituted C1-C6 alkoxy, O-(optionally substituted phenyl), optionally substituted phenyl, SO.sub.2-(optionally substituted phenyl), SO.sub.2-(optionally substituted alkyl), and halogen.

4. The compound of claim 1 or 3, wherein Ar comprises a halogen substituent.

5. The compound of any of claims 1-4, wherein R.sup.1 and R.sup.2 are both H.

6. The compound of claim 1, wherein R.sup.1 and Ar together form a dihydroindole moiety.

7. The compound of claim 1, wherein R.sup.3 and Ar together form an indane moiety.

8. The compound of any of claims 1-7, wherein m is 0 and n is 0.

9. The compound of any of claims 1-7, wherein m is 1 and n is O.

10. The compound of any of claims 1-7, wherein m is 0 and n is 1.

11. The compound of any of claims 1-7, wherein m is 1 and n is 1.

12. The compound of claim 1, wherein said compound is selected from compounds 51-59 in Table 1.

13. A compound of Formula II: ##STR00123## wherein R.sup.1 is H or optionally substituted C1-C6 alkyl; or R.sup.1 combines with R.sup.2 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.1 combines with R.sup.3 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.1 combines with R.sup.5 to form an optionally substituted 5- to 6-membered heterocyclyl; R.sup.2 is H or optionally substituted C1-C6 alkyl, or R.sup.2 combines with R.sup.1 to form an optionally substituted C5-C6 cycloalkyl or an optionally substituted 5- to 6-membered heterocyclyl; R.sup.3 is H, optionally substituted C1-C6 alkyl, optionally substituted phenyl, or optionally substituted alkaryl; or R.sup.3 combines with R.sup.1 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.3 combines with R.sup.4 to form an optionally substituted C3-C6 cycloalkyl or a carbonyl group; or R.sup.3 combines with R.sup.5 to form an optionally substituted 5- to 6-membered heterocyclyl or an optionally substituted C5-C6 cycloalkyl; R.sup.4 is H or optionally substituted C1-C6 alkyl; or R3 combines with R4 to form an optionally substituted C3-C6 cycloalkyl or a carbonyl group; n is 0, 1, or 2; each R.sup.5, when present, is independently H or optionally substituted C1-C6 alkyl; or R.sup.5 combines with R.sup.1 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.5 combines with R.sup.3 to form an optionally substituted 5- to 6-membered heterocyclyl or an optionally substituted substituted C5-C6 cycloalkyl; each R.sup.6, when present, is independently H or optionally substituted C1-C6 alkyl; R.sup.7 is H or optionally substituted C1-C6 alkyl; L.sup.1 is optionally substituted C1-C6 alkylene; and Ar is an optionally substituted phenyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

14. The compound of claim 13, wherein R.sup.7 is H.

15. The compound of claim 13 or 14, wherein L.sup.1 is an optionally substituted C1-C3 alkylene that is linear or branched.

16. The compound of claim 15, wherein said C1-C3 alkylene is unsubstituted.

17. The compound of claim 15, wherein L.sup.1 is a C1-C3 alkylene comprising an optionally substituted phenyl group.

18. The compound of claim 15, wherein -L.sup.1-O has a structure selected from: ##STR00124##

19. The compound of any of claims 13-18, wherein R.sup.1 is H.

20. The compound of claim 19, wherein R.sup.2 is H or optionally substituted C1-C2 alkyl.

21. The compound of any of claims 13-18, wherein R.sup.1 and R.sup.2 combine to form an unsubstituted 5- to 6-membered heterocyclyl or a 5- to 6-membered heterocyclyl comprising an oxo substituent.

22. The compound of claim 21, wherein NR.sup.1R.sup.2 has a structure that is ##STR00125##

23. The compound of any of claims 13-20, wherein R.sup.1 and R.sup.3 combine to form an unsubstituted 5- to 6-membered heterocyclyl.

24. The compound of any of claims 13-22, wherein R.sup.3 is H, optionally substituted C1-C6 alkyl, or optionally substituted phenyl.

25. The compound of any of claims 13-24, wherein R.sup.4 is H or unsubstituted C1-C6 alkyl.

26. The compound of any of claims 13-22, wherein R.sup.3 and R.sup.4 combine to form: ##STR00126##

27. The compound of any of claims 13-26, wherein n is 0.

28. The compound of claim 13-26, wherein n is 1.

29. The compound of claim 28, wherein R.sup.5 and R.sup.6 are both H.

30. The compound of any of claims 13-22 and 27, wherein R.sup.3 and R.sup.5 combine to form an unsubstituted cyclohexyl.

31. The compound of any of claim 13-20 or 27, wherein R.sup.1 and R.sup.5 combine to form an unsubstituted morpholino group.

32. The compound of any of claims 13-26, wherein n is 2.

33. The compound of claim 32, wherein R.sup.5 and R.sup.6 are selected, independently, from H and optionally substituted C1-C6 alkyl.

34. The compound of any of claims 13-33, wherein Ar is phenyl comprising 1, 2, or 3 substituents selected from: optionally substituted C1-C6 alkyl, optionally substituted C1-C6 alkoxy, O-(optionally substituted phenyl), optionally substituted phenyl, SO.sub.2-(optionally substituted phenyl), SO.sub.2-(optionally substituted alkyl), and halogen.

35. The compound of any of claims 13-34, wherein Ar is phenyl comprising a substituent that is optionally substituted C1-C6 alkyl or halogen.

36. The compound of any of claims 13-35, wherein Ar is phenyl substituted with one or more substituents selected from the group consisting of methyl, trifluoromethyl, and fluorine.

37. The compound of any of claims 13-36, wherein the carbon bearing the NR.sup.1R.sup.2 group has the (S)-configuration.

38. The compound of any of claims 13-36, wherein the carbon bearing the NR.sup.1R.sup.2 group has the (R)-configuration.

39. The compound of claim 13, wherein the compound is selected from any one of compounds 1-37 in Table 1.

40. A compound of Formula III: ##STR00127## wherein R.sup.1 is selected from hydrogen and optionally substituted C1-C6 alkyl; R.sup.2 and R.sup.3 are independently selected from hydrogen; optionally substituted C1-C6 alkyl; optionally substituted C3-C6 cycloalkyl; and optionally substituted aromatic; and each of R.sup.4, R.sup.5, R.sup.6, and R.sup.7 is independently selected from H, optionally substituted C1-C6 alkyl, optionally substituted C1-C6 alkoxy, O-(optionally substituted phenyl), optionally substituted phenyl, SO.sub.2-(optionally substituted phenyl), SO.sub.2-(optionally substituted C1-C6 alkyl), and halogen; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

41. The compound of claim 40, wherein R.sup.1 is H.

42. The compound of claim 40 or 41, wherein R.sup.3, R.sup.5, and R.sup.7 are H.

43. The compound of any of claims 40-42, wherein R.sup.2 is C1-C6 alkyl comprising an optionally substituted amino group.

44. The compound of claim 43, wherein R.sup.2 is (CH.sub.2).sub.mNH.sub.2, wherein m is 1, 2, or 3.

45. The compound of any of claims 40-44, wherein R.sup.4 and R.sup.6 are independently selected from optionally substituted C1-C6 alkyl.

46. The compound of claim 45, wherein R.sup.4 and R.sup.6 are both trifluoromethyl.

47. The compound of claim any of claims 40-46, wherein the carbon bearing R.sup.2 and R.sup.3 has the (S)-configuration.

48. The compound of any of claims 40-46, wherein the carbon bearing R.sup.2 and R.sup.3 has the (R)-configuration.

49. The compound of claim 40, wherein the compound is selected from compounds 39-40 in Table 1.

50. A compound of Formula IV: ##STR00128## wherein R.sup.1 is selected from hydrogen and optionally substituted C1-C6 alkyl; and R.sup.2 and R.sup.3 are independently selected from hydrogen; optionally substituted C1-C6 alkyl; optionally substituted C3-C6 cycloalkyl; and optionally substituted phenyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

51. The compound of claim 50, wherein R.sup.1 is H.

52. The compound of claim 50 or 51, wherein R.sup.2 is H or optionally substituted C1-C3 alkyl.

53. The compound of any of claims 50-52, wherein R.sup.3 is optionally substituted phenyl.

54. The compound of claim 53, wherein R.sup.3 is phenyl comprising 1 or 2 substituents that are, independently, C1-C3 haloalkyl.

55. The compound of claim 50, wherein the compound is selected from compounds 41-42 in Table 1.

56. A compound of Formula V: ##STR00129## wherein R.sup.1 is an optionally substituted C5-C6 heterocylyl or optionally substituted C1-C6 aminoalkyl; R.sup.2 is hydrogen or optionally substituted C1-C6 alkyl; and R.sup.3, R.sup.4, and R.sup.5 are independently selected from optionally substituted C1-C6 alkyl, optionally substituted C1-C6 heteroalkyl, optionally substituted C6-C10 aryl, optionally substituted heteroaryl, and optionally substituted alkaryl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

57. The compound of claim 56, wherein R.sup.2 is H.

58. The compound of claim 56 or 57, wherein R.sup.3 is H.

59. The compound of any of claims 56-58, wherein R.sup.4 and R.sup.5 are independently selected from H and optionally substituted C1-C6 alkyl.

60. The compound of any of claims 56-58, wherein R.sup.4 and R.sup.5 are independently selected from H and methyl.

61. The compound of any of claims 56-60, wherein R.sup.1 is: ##STR00130##

62. The compound of any of claims 56-60, wherein R.sup.1 is ##STR00131##

63. The compound of claim 56, wherein the compound is selected from compounds 43-46 in Table 1.

64. A compound of Formula VI: ##STR00132## wherein R.sup.1 is selected from hydrogen and optionally substituted C1-C6 alkyl; m is 0, 1, 2, 3, or 4; each R.sup.2 is selected, independently, from halogen, CN, NO.sub.2, COOR, CONR.sub.2, OR, SR, SOR, SO.sub.2R, NR.sub.2, NR(CO)R, and NRSO.sub.2R, wherein each R is independently H or an optionally substituted group selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C2-C6 heteroalkyl, C2-C6 heteroalkenyl, and C2-C6 heteroalkynyl; or each R.sup.2 is independently an optionally substituted group selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C2-C6 heteroalkyl, C2-C6 heteroalkenyl, or C2-C6 heteroalkynyl; or wherein two R.sup.2 on the same carbon combine to form O and NOR; and R.sup.3 and R.sup.4 is independently selected from hydrogen; optionally substituted C1-C6 alkyl; optionally substituted C3-C6 cycloalkyl; optionally substituted C3-C6 heterocyclyl; SO.sub.2R.sup.5, wherein R.sup.5 is amino, optionally substituted C1-C6 alkyl, or optionally substituted phenyl; or R.sup.1 and R.sup.2 together form an optionally substituted 3- to 7-membered heterocyclyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

65. The compound of claim 64, wherein R.sup.1 is H.

66. The compound of claim 64 or 65, wherein R.sup.4 is H.

67. The compound of any of claims 64-66, wherein m is 1.

68. The compound of any of claims 64-67, wherein R.sup.2 is O.

69. The compound of any of claims 64-68, wherein R.sup.3 is selected from H and optionally substituted C1-C6 alkyl.

70. The compound of any of claims 64-69, wherein R.sup.3 is ##STR00133##

71. The compound of claim 64, wherein the compound is compound 47 in Table 1.

72. A compound of Formula VII: ##STR00134## wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from H, optionally substituted C1-C6 alkyl, optionally substituted C1-C6 alkoxy, O-(optionally substituted phenyl), optionally substituted phenyl, SO.sub.2-(optionally substituted phenyl), SO.sub.2-(optionally substituted C1-C6 alkyl), and halogen; L.sup.1 is selected from a covalent bond; optionally substituted C1-C3 alkylene; and optionally substituted C1 to C3 heteroalkylene; R.sup.5 together with C(O) is an amino acid residue; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

73. The compound of claim 72, wherein L.sup.1 is unsubstituted C1-C3 alkylene.

74. The compound of claim 72 or 73, wherein R.sup.1, R.sup.3, and R.sup.4 are H.

75. The compound of any of claims 72-74, wherein R.sup.2 is selected from H, optionally substituted C1-C6 alkyl, and halogen.

76. The compound of any of claims 72-75, wherein R.sup.3 is fluorine.

77. The compound of any of claims 72-76, wherein R.sup.5 is ##STR00135##

78. The compound of claim 72, wherein the compound is compound 48 in Table 1.

79. A compound of Formula VIII: ##STR00136## wherein Het is an optionally substituted C3-C6 heterocyclyl; n is 0 or 1; and Ar is an optionally substituted phenyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

80. The compound of claim 79, wherein Ar comprises a substituent group that is optionally substituted C1-C6 alkyl, optionally substituted C1-C6 alkoxy, O-(optionally substituted phenyl), optionally substituted phenyl, SO.sub.2-(optionally substituted phenyl), SO.sub.2-(optionally substituted alkyl), or halogen.

81. The compound of any of claims 79-80, wherein Ar comprises a substituent group that is optionally substituted C1-C3 alkyl or optionally substituted C1-C3 alkoxy.

82. The compound of any of claims 79-81, where Ar comprises a substituent group that is trifluoromethyl or trifluoromethoxy.

83. The compound of any of claims 79-82, wherein n is 0.

84. The compound of claim 83, wherein Het is ##STR00137##

85. The compound of any of claims 79-82, wherein n is 1.

86. The compound of claim 85, wherein Het is ##STR00138##

87. The compound of claim 79, wherein the compound is selected from compounds 49-50 in Table 1.

88. A compound of Formula IX: ##STR00139## wherein R.sup.1 and R.sup.2 are independently selected from H, optionally substituted C1-C6 alkyl, and halogen; L.sup.1 is optionally substituted C1-C6 alkylene; m is 0, 1, 2, 3, or 4; and each R.sup.3 is selected, independently, from halogen, CN, NO.sub.2, COOR, CONR.sub.2, OR, SR, SOR, SO.sub.2R, NR.sub.2, NR(CO)R, and NRSO.sub.2R, wherein each R is independently H or an optionally substituted group selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C2-C6 heteroalkyl, C2-C6 heteroalkenyl, and C2-C6 heteroalkynyl; or each R.sup.2 is independently an optionally substituted group selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C2-C6 heteroalkyl, C2-C6 heteroalkenyl, or C2-C6 heteroalkynyl; or wherein two R.sup.2 on the same carbon combine to form O and NOR; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

89. The compound of claim 88, wherein L.sup.1 is selected from: ##STR00140##

90. The compound of any of claims 88-89, wherein R.sup.1 and R.sup.2 are independently selected from H, optionally substituted C1 to C6 alkyl, and halogen.

91. The compound of any of claims 88-90, wherein m is 0.

92. The compound of any of claims 88-90, wherein m is 1.

93. The compound of any of claims 88-92, wherein R.sup.3 is CO.

94. The compound of claim 88, wherein said compound is selected from compounds 60-70 in Table 1.

95. A compound of Formula X: ##STR00141## wherein Het is optionally substituted phenyl, optionally substituted pyridine, or optionally substituted benzimidazole; R.sup.1 is H or optionally substituted C1 to C6 alkyl; R.sup.2 is H, optionally substituted C1 to C6 alkyl, or optionally substituted C1 to C6 alkoxy; R.sup.3 is H, optionally substituted C1-C6 alkyl, optionally substituted C1 to C6 alkoxy, or optionally substituted phenyl; or R.sup.3 combines with R.sup.4 to an optionally substituted 5- to 6-membered heterocyclyl; R.sup.4 is H or optionally substituted C1-C6 alkyl; or R.sup.4 combines with R.sup.5 to form an optionally substituted 5- to 6-membered heterocyclyl; or R.sup.4 combines with R.sup.3 to form an optionally substituted 5- to 6-membered heterocyclyl; and R.sup.5 is H or optionally substituted C1-C6 alkyl, or R.sup.5 combines with R.sup.4 to form an optionally substituted C5-C6 cycloalkyl or an optionally substituted 5- to 6-membered heterocyclyl; or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

96. The compound of claim 95, wherein Het is selected from: ##STR00142##

97. The compound of any of claims 95-96, wherein R.sup.1 and R.sup.2 are independently selected from H and methyl.

98. The compound of any of claims 95-97, wherein R.sup.4 is H.

99. The compound of any of claims 95-98, wherein R.sup.5 is H or optionally substituted C1-C6 alkyl.

100. The compound of claim 95, wherein R.sup.4 and R.sup.5 combine to form: ##STR00143##

101. The compound of claim 95-97, wherein R.sup.3 and R.sup.4 combine to form: ##STR00144##

102. The compound of claim 95, wherein said compound is selected from compounds 71-83 in Table 1.

103. A compound selected from compounds 84-92 in Table 1.

104. The stereoisomer of the compound of any of claims 1-103.

105. The pharmaceutically acceptable salt of the compound of any of claims 1-103, or of the stereoisomer of claim 104.

106. A pharmaceutical composition comprising (1) the compound of any of claims 1-103, or the stereoisomer of claim 104, or the pharmaceutically acceptable salt of claim 105; and (2) a pharmaceutically acceptable carrier or excipient.

107. The pharmaceutical composition of claim 106, wherein said pharmaceutical composition is formulated in unit dosage form.

108. The pharmaceutical composition of claim 107, wherein said unit dosage form is a tablet, caplet, capsule, lozenge, film, strip, gelcap, or syrup.

109. A method to treat a disease or condition, said method comprising administering to a subject in need of such treatment an effective amount of the compound of any of claims 1-103; the stereoisomer of claim 104; the pharmaceutically acceptable salt of claim 105; or the pharmaceutical composition of any of claims 106-108.

110. The method of claim 109, wherein said condition is pain, epilepsy, Parkinson's disease, mood disorders, psychosis, tinnitus, amyotropic lateral sclerosis, glaucoma, ischaemia, spasticity disorders, obsessive compulsive disorder, restless leg syndrome, or Tourette syndrome.

111. The method of claim 110, wherein said condition is pain, epilepsy, Parkinson's disease, mood disorders, psychosis, or tinnitus.

112. The method of claim 110, wherein said psychosis is schizophrenia.

113. The method of claim 110, wherein said condition is pain or epilepsy.

114. The method of claim 113, wherein said pain is inflammatory pain or neuropathic pain.

115. The method of claim 114, wherein said inflammatory pain is caused by rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease, primary dysmenorrhea, or endometriosis.

116. The method of claim 113, wherein said pain is chronic pain.

117. The method of claim 116, wherein said chronic pain is peripheral neuropathic pain, central neuropathic pain, musculoskeletal pain, headache, visceral pain, or mixed pain.

118. The method of claim 117, wherein said peripheral neuropathic pain is post-herpetic neuralgia, diabetic neuropathic pain, neuropathic cancer pain, HIV-associated neuropathy, erythromelalgia, failed back-surgery syndrome, trigeminal neuralgia, or phantom limb pain; said central neuropathic pain is multiple sclerosis related pain, Parkinson disease related pain, post-stroke pain, post-traumatic spinal cord injury pain, lumbosacral radiculopathy, cervical radiculopathy, brachial radiculopathy, or pain in dementia; said musculoskeletal pain is osteoarthritic pain or fibromyalgia syndrome; said headache is migraine, cluster headache, tension headache syndrome, facial pain, or headache caused by other diseases; said visceral pain is interstitial cystitis, irritable bowel syndrome, or chronic pelvic pain syndrome; or said mixed pain is lower back pain, neck and shoulder pain, burning mouth syndrome, or complex regional pain syndrome.

119. The method of claim 118, wherein said headache is migraine.

120. The method of claim 113, wherein said pain is acute pain.

121. The method of claim 120, wherein said acute pain is nociceptive pain or post-operative pain.

122. The method of claim 121, wherein said acute pain is post-operative pain.

123. A method of inhibiting a voltage-gated sodium channel, said method comprising contacting a cell with the compound of any of claims 1-103; the stereoisomer of claim 104; the pharmaceutically acceptable salt of claim 105; or the pharmaceutical composition of any of claims 106-108.

Description

DETAILED DESCRIPTION OF THE INVENTION

Compounds

[0212] The invention features compounds that can inhibit voltage-gated ion channel activity (e.g., voltage-gated sodium channels) by state-dependent enhancement of slow-inactivation and other use-dependent mechanisms. Exemplary compounds described herein include compounds having a structure according the following formulae (I)-(X) as described herein:

##STR00025## ##STR00026##

or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof.

[0213] Other embodiments (e.g., Compounds (1)-(92) of Table 1), as well as exemplary methods for the synthesis of these compounds, are described herein.

Utility and Administration

[0214] The compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) are useful in the methods of the invention and, while not bound by theory, are believed to exert their desirable effects through their ability to modulate the activity of voltage-gated ion channels, e.g., sodium channels such as the Nav1.7 and Nav1.8 channels. The compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) can also be used for the treatment of certain conditions such as pain, epilepsy, migraine, Parkinson's disease, mood disorders, schizophrenia, psychosis, tinnitus, amyotropic lateral sclerosis, glaucoma, ischaemia, spasticity disorders, obsessive compulsive disorder, restless leg syndrome, and Tourette syndrome.

Modulation of Sodium Channels

[0215] There are nine Nav1 -subunit isoforms: Nav1.1-1.9 (see, e.g., Yu et al., Genome Biolog, 4:207, 2003). In addition to pain, other conditions associated with voltage-dependent sodium channel activity include seizures (e.g., Nav1.1), epilepsy (e.g., Nav1.2), neurodegeneration (e.g., Nav1.1, Nav1.2), myotonia (e.g., Nav1.4), arrhythmia (e.g., Nav1.5), and movement disorders (e.g., Nav1.6) as described in PCT Publication No. WO 2008/118758, herein incorporated by reference. The expression of particular isoforms in particular tissues can influence the therapeutic effects of sodium channel modulators. For example, the Nav1.4 and Nav1.5 isoforms are largely found in skeletal and cardiac myocytes (see, e.g., Gold, Exp. Neurol. 210(1): 1-6, 2008).

[0216] Sodium Channel Activity and Pain

[0217] Voltage-dependent ion channels in pain-sensing neurons are currently of great interest in developing drugs to treat pain. For example, blocking voltage-dependent sodium channels in pain-sensing neurons can block pain signals by interrupting initiation and transmission of the action potential. Studies also indicate that particular sodium channel isoforms are predominantly expressed in peripheral sensory neurons associated with pain sensation; for example, Nav1.7, Nav1.8 and Nav1.9 activity are thought to be involved in inflammatory, and possibly neuropathic, pain (see, e.g., Cummins et al., Pain, 131(3):243-257, 2007). The Nav1.3 isoform has also been implicated in pain, e.g., pain associated with tissue injury (Gold, Exp. Neurol. 210(1): 1-6, 2008).

[0218] The Nav1.7 and Nav1.8 channel subtypes act as major contributors to both inflammatory and neuropathic pain (vide infra). Recently, mutations have been identified in the Nav1.7 channel that lead either to a gain of channel function (Dib-Hajj et al., Brain 128:1847-1854, 2005) or more commonly to a loss of channel function (Chatelier et al., J. Neurophisiol. 99:2241-50, 2008). These mutations underlie human heritable disorders such as erythrormelalgia (Yang et al., J. Med. Genet. 41(3) 171-4, 2004), paroxysmal extreme pain disorder (Fertleman et al., Neuron. 52(5) 767-74, 2006), and congenital indifference to pain (Cox et al., Nature 444(7121):894-8, 2006). Behavioral studies have shown in mice that inflammatory and acute mechanosensory pain is reduced when Nav1.7 is knocked out in Nav1.8-positive neurons (Nassar et al., Proc. Natl. Acad. Sci. USA. 101(34):12706-11, 2004). In addition, siRNA of Nav1.7 attenuates inflammatory hyperalgesia (Yeomans et al., Hum Gene Ther. 16(2) 271-7, 2005).

[0219] The Nav1.8 isoform is selectively expressed in sensory neurons and has been identified as a target for the treatment of pain, e.g., chronic pain (e.g., Swanwick et al., Neurosci. Lett. 486:78-83, 2010). The role of Nav1.8 in inflammatory (Khasar et al. Neurosci. Lett. 256(1):17-20, 1998), neuropathic, and mechanical hyperalgesia (Joshi et al., Pain 123(1-2):75-82, 2006) has also emerged using molecular techniques to knockdown Nav1.8, which has been shown to reduce the maintenance of these different pain states.

[0220] Lacosamide is a functionalized amino acid that has shown effectiveness as an analgesic in several animal models of neuropathic pain and is currently in late stages of clinical development for epilepsy and diabetic neuropathic pain. One mode of action that has been validated for lacosamide is inhibition of voltage-gated sodium channel activity by selective inhibition with the slow-inactivated conformation of the channel (Sheets et al., Journal of Pharmacology and Experimental Therapeutics, 326(1) 89-99 (2008)). Modulators of sodium channels, including clinically relevant compounds, can exhibit a pronounced state-dependent binding, where sodium channels that are rapidly and repeatedly activated and inactivated are more readily blocked. In a simplified scheme, voltage-gated sodium channels have four distinct states: open, closed, fast-inactivated and slow-inactivated. Classic sodium channel modulators, such as lidocaine, are believed to exhibit the highest affinity for the fast-inactivated state. However, alteration of the slow inactivated state is also clinically relevant. As demonstrated by gain-of-function mutations of the Nav1.7 gene, SCN9A, a subset of mutations that promote entry of the Nav1.7 channel into the slow inactivated state result in less severe forms of erythromelalgia (Cheng et al., Brain. 134(Pt 7):1972-1986, 2011). Because repeated Nav1.7 channel activation results in greater proportions of the channel to be in the slow inactivated state and further stabilization of the channel in the slow-inactivated state limits pain, the identification of modulators that enhance ion channel entry into the slow inactivated state would be believed to produce a therapeutic analgesic effect (Blair and Bean, J Neurosci. 23(32):10338-20350, 2003).

[0221] The modulation of ion channels by the compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) can be measured according to methods known in the art (e.g., in the references provided herein) to monitor both use- and state-dependence (Tables 2 and 3). This electrophysiological data can be used to further characterize the modulators as enhancers of slow inactivation (Table 3). Modulators of ion channels, e.g., voltage gated sodium ion channels, and the medicinal chemistry or methods by which such compounds can be identified, are also described in, for example: Birch et al., Drug Discovery Today, 9(9):410-418 (2004); Audesirk, Chapter 6-Electrophysiological Analysis of Ion Channel Function, Neurotoxicology: Approaches and Methods, 137-156 (1995); Camerino et al., Chapter 4: Therapeutic Approaches to Ion Channel Diseases, Advances in Genetics, 64:81-145 (2008); Petkov, Chapter 16-Ion Channels, Pharmacology: Principles and Practice, 387-427 (2009); Standen et al., Chapter 15-Patch Clamping Methods and Analysis of Ion Channels, Principles of Medical Biology, Vol. 7, Part 2, 355-375 (1997); Xu et al., Drug Discovery Today, 6(24):1278-1287 (2001); and Sullivan et al., Methods Mol. Biol. 114:125-133 (1999). Exemplary experimental methods are also provided in the Examples.

Diseases and Conditions

[0222] Exemplary conditions that can be treated using the compounds described herein include pain (e.g., chronic or acute pain), epilepsy, Alzheimer's disease, Parkinson's disease, diabetes; cancer; sleep disorders; obesity; psychosis such as schizophrenia; overactive bladder; renal disease, neuroprotection, and addiction. For example, the condition can be pain (e.g., neuropathic pain or post-surgery pain), epilepsy, migraine, Parkinson's disease, mood disorders, schizophrenia, psychosis, tinnitus, amyotrophic lateral sclerosis, glaucoma, ischaemia, spasticity disorders, obsessive compulsive disorder, restless leg syndrome and Tourette syndrome.

[0223] Epilepsy as used herein includes but is not limited to partial seizures such as temporal lobe epilepsy, absence seizures, generalized seizures, and tonic/clonic seizures.

[0224] Cancer as used herein includes but is not limited to breast carcinoma, neuroblastoma, retinoblastoma, glioma, prostate carcinoma, esophageal carcinoma, fibrosarcoma, colorectal carcinoma, pheochromocytoma, adrenocarcinoma, insulinoma, lung carcinoma, melanoma, and ovarian cancer.

[0225] Acute pain as used herein includes but is not limited to nociceptive pain and post-operative pain. Chronic pain includes but is not limited by: peripheral neuropathic pain (e.g., post-herpetic neuralgia, diabetic neuropathic pain, neuropathic cancer pain, HIV-associated neuropathy, erythromelalgia, failed back-surgery syndrome, trigeminal neuralgia, or phantom limb pain); central neuropathic pain (e.g., multiple sclerosis related pain, Parkinson disease related pain, post-stroke pain, post-traumatic spinal cord injury pain, lumbosacral radiculopathy, cervical radiculopathy, brachial radiculopathy, or pain in dementia); musculoskeletal pain such as osteoarthritic pain and fibromyalgia syndrome; inflammatory pain (e.g., inflammatory pain caused by rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease, primary dysmenorrhea, or endometriosis); headache such as migraine, cluster headache, tension headache syndrome, facial pain, headache caused by other diseases; visceral pain such as interstitial cystitis, irritable bowel syndrome and chronic pelvic pain syndrome; and mixed pain such as lower back pain, neck and shoulder pain, burning mouth syndrome and complex regional pain syndrome.

[0226] In treating osteoarthritic pain, joint mobility can also improve as the underlying chronic pain is reduced. Thus, use of compounds of the present invention to treat osteoarthritic pain inherently includes use of such compounds to improve joint mobility in patients suffering from osteoarthritis.

[0227] The compounds described herein can be tested for efficacy in any standard animal model of pain. Various models test the sensitivity of normal animals to intense or noxious stimuli (physiological or nociceptive pain). These tests include responses to thermal, mechanical, or chemical stimuli. Thermal stimuli usually involve the application of hot stimuli (typically varying between 42-55 C.) including, for example: radiant heat to the tail (the tail flick test), radiant heat to the plantar surface of the hindpaw (the Hargreaves test), the hotplate test, and immersion of the hindpaw or tail into hot water. Immersion in cold water, acetone evaporation, or cold plate tests may also be used to test cold pain responsiveness. Tests involving mechanical stimuli typically measure the threshold for eliciting a withdrawal reflex of the hindpaw to graded strength monofilament von Frey hairs or to a sustained pressure stimulus to a paw (e.g., the Ugo Basile analgesiometer). The duration of a response to a standard pinprick may also be measured. When using a chemical stimulus, the response to the application or injection of a chemical irritant (e.g., capsaicin, mustard oil, bradykinin, ATP, formalin, acetic acid) to the skin, muscle joints or internal organs (e.g., bladder or peritoneum) is measured.

[0228] In addition, various tests assess pain sensitization by measuring changes in the excitability of the peripheral or central components of the pain neural pathway. In this regard, peripheral sensitization (i.e., changes in the threshold and responsiveness of high threshold nociceptors) can be induced by repeated heat stimuli as well as the application or injection of sensitizing chemicals (e.g., prostaglandins, bradykinin, histamine, serotonin, capsaicin, or mustard oil). Central sensitization (i.e., changes in the excitability of neurons in the central nervous system induced by activity in peripheral pain fibers) can be induced by noxious stimuli (e.g., heat), chemical stimuli (e.g., injection or application of chemical irritants), or electrical activation of sensory fibers.

[0229] Various pain tests developed to measure the effect of peripheral inflammation on pain sensitivity can also be used to study the efficacy of the compounds (Stein et al., Pharmacol. Biochem. Behav. (1988) 31: 445-451; Woolf et al., Neurosci. (1994) 62: 327-331). Additionally, various tests assess peripheral neuropathic pain using lesions of the peripheral nervous system. One such example is the axotomy pain model (Watson, J. Physiol. (1973) 231:41). Other similar tests include the SNL test which involves the ligation of a spinal segmental nerve (Kim and Chung Pain (1992) 50: 355), the Seltzer model involving partial nerve injury (Seltzer, Pain (1990) 43: 205-18), the spared nerve injury (SNI) model (Decosterd and Woolf, Pain (2000) 87:149), chronic constriction injury (CCI) model (Bennett (1993) Muscle Nerve 16: 1040), tests involving toxic neuropathies such as diabetes (streptozocin model), pyridoxine neuropathy, taxol, vincristine, and other antineoplastic agent-induced neuropathies, tests involving ischaemia to a nerve, peripheral neuritis models (e.g., CFA applied peri-neurally), models of post-herpetic neuralgia using HSV infection, and compression models.

[0230] In all of the above tests, outcome measures may be assessed, for example, according to behavior, electrophysiology, neurochemistry, or imaging techniques to detect changes in neural activity.

[0231] Exemplary disease models include, but are not limited to, the following models described below.

[0232] Pain Models

[0233] L5/L6 Spinal Nerve Ligation (SNL)Chung Pain Model

[0234] The Spinal Nerve Ligation is an animal model representing peripheral nerve injury generating a neuropathic pain syndrome. In this model experimental animals develop the clinical symptoms of tactile allodynia and hyperalgesia. L5/L6 Spinal nerve ligation (SNL) injury was induced using the procedure of Kim and Chung (Kim et al., Pain 50:355-363 (1992)) in male Sprague-Dawley rats (Harlan; Indianapolis, Ind.). An exemplary protocol is provided below.

[0235] Animals can be anesthetized with isoflurane, and the left L6 transverse process can be removed, and the L5 and L6 spinal nerves can be tightly ligated with 6-0 silk suture. The wound can then be closed with internal sutures and external tissue adhesive. Rats that exhibit motor deficiency (such as paw-dragging) or failure to exhibit subsequent tactile allodynia can be excluded from further testing.

[0236] Sham control rats can undergo the same operation and handling as the experimental animals, but without SNL.

[0237] Assessment of Mechanical Hyperalgesia

[0238] Baseline and post-treatment values for mechanical hyperalgesia can be evaluated using a digital Randall-Selitto device (dRS; IITC Life Sciences, Woodland Hills, Calif.). Animals can be allowed to acclimate to the testing room for a minimum of 30 minutes before testing. Animals can be placed in a restraint sling that suspends the animal, leaving the hind limbs available for testing. Paw compression threshold was measured once at each time point for the ipsilateral and contralateral paws. The stimulus can be applied to the plantar surface of the hind paw by a dome-shaped tip placed between the 3rd and 4th metatarsus, and pressure can be applied gradually over approximately 10 seconds. Measurements can be taken from the first observed nocifensive behavior of vocalization, struggle or withdrawal. A cut-off value of 300 g can be used to prevent injury to the animal. The mean and standard error of the mean (SEM) can be determined for each paw for each treatment group. Fourteen days after surgery, mechanical hyperalgesia can be assessed, and rats can be assigned to treatment groups based on pre-treatment baseline values. Prior to initiating drug delivery, baseline behavioural testing data can be obtained. At selected times after infusion of the Test or Control Article behavioural data can then be collected again.

[0239] Assessment of Tactile AllodyniaVon Frey

[0240] The assessment of tactile allodynia can consist of measuring the withdrawal threshold of the paw ipsilateral to the site of nerve injury in response to probing with a series of calibrated von Frey filaments (innocuous stimuli). Animals can be acclimated to the suspended wire-mesh cages for 30 min before testing. Each von Frey filament can be applied perpendicularly to the plantar surface of the ligated paw of rats for 5 sec. A positive response can be indicated by a sharp withdrawal of the paw. For rats, the first testing filament is 4.31. Measurements can be taken before and after administration of test articles. The paw withdrawal threshold can be determined by the non-parametric method of Dixon (Dixon, Ann. Rev. Pharmacol. Toxicol. 20:441-462 (1980)), in which the stimulus was incrementally increased until a positive response was obtained, and then decreased until a negative result was observed. The protocol can be repeated until three changes in behaviour were determined (up and down method; Chaplan et al., J. Neurosci. Methods 53:55-63 (1994)). The 50% paw withdrawal threshold can be determined as (10.sup.[xf+k])/10,000, where X.sub.f=the value of the last von Frey filament employed, k=Dixon value for the positive/negative pattern, and =the logarithmic difference between stimuli. The cut-off values for rats can be, for example, no less than 0.2 g and no higher than 15 g (5.18 filament); for mice no less than 0.03 g and no higher than 2.34 g (4.56 filament). A significant drop of the paw withdrawal threshold compared to the pre-treatment baseline is considered tactile allodynia. Rat SNL tactile allodynia can be tested for the compounds described herein at, e.g., 60 minutes compared to baseline and post-SNL.

[0241] Assessment of Thermal HypersensitivityHargreaves

[0242] The method of Hargreaves and colleagues (Hargreaves et al., Pain 32:77-8 (1988)) can be employed to assess paw-withdrawal latency to a noxious thermal stimulus.

[0243] Rats may be allowed to acclimate within a Plexiglas enclosure on a clear glass plate for 30 minutes. A radiant heat source (e.g., halogen bulb coupled to an infrared filter) can then be activated with a timer and focused onto the plantar surface of the affected paw of treated rats. Paw-withdrawal latency can be determined by a photocell that halts both lamp and timer when the paw is withdrawn. The latency to withdrawal of the paw from the radiant heat source can be determined prior to L5/L6 SNL, 7-14 days after L5/L6 SNL but before drug, as well as after drug administration. A maximal cut-off of 33 seconds is typically employed to prevent tissue damage. Paw withdrawal latency can be thus determined to the nearest 0.1 second. A significant drop of the paw withdrawal latency from the baseline indicates the status of thermal hyperalgesia. Antinociception is indicated by a reversal of thermal hyperalgesia to the pre-treatment baseline or a significant (p<0.05) increase in paw withdrawal latency above this baseline. Data is converted to % anti hyperalgesia or anti nociception by the formula: (100(test latencybaseline latency)/(cut-offbaseline latency) where cut-off is 21 seconds for determining anti hyperalgesia and 40 seconds for determining anti nociception.

[0244] Epilepsy Models

[0245] 6 Hz Psychomotor Seizure Model of Partial Epilepsy

[0246] Compounds can be evaluated for the protection against seizures induced by a 6 Hz, 0.2 ms rectangular pulse width of 3 s duration, at a stimulus intensity of 32 mA (CC97) applied to the cornea of male CF1 mice (20-30 g) according to procedures described by Barton et al, Pharmacological Characterization of the 6 Hz Psychomotor Seizure Model of Partial Epilepsy, Epilepsy Res. 47(3):217-27 (2001). Seizures are characterised by the expression of one or more of the following behaviours: stun, forelimb clonus, twitching of the vibrissae and Straub-tail immediately following electrical stimulation. Animals can be considered protected if, following pre-treatment with a compound, the 6 Hz stimulus failed to evoke a behavioural response as describe above.

[0247] Assessments of Neurological or Muscular Impairments

[0248] To assess a compound's undesirable side effects (toxicity), animals can be monitored for overt signs of impaired neurological or muscular function. In mice, the rotarod procedure (Dunham et al., J. Am. Pharmacol. Assoc. 46:208-209 (1957)) is used to disclose minimal muscular or neurological impairment (MMI). When a mouse is placed on a rod that rotates at a speed of 6 rpm, the animal can maintain its equilibrium for long periods of time. The animal is considered toxic if it falls off this rotating rod three times during a 1-min period. In addition to MMI, animals may exhibit a circular or zigzag gait, abnormal body posture and spread of the legs, tremors, hyperactivity, lack of exploratory behavior, somnolence, stupor, catalepsy, loss of placing response and changes in muscle tone.

[0249] Recordings on Lamina I/II Spinal Cord Neurons

[0250] Male Wistar rats (P6 to P9 for voltage-clamp and P15 to P18 for current-clamp recordings) can be anaesthetized through intraperitoneal injection of Inactin (Sigma). The spinal cord can then be rapidly dissected out and placed in an ice-cold solution protective sucrose solution containing (in mM): 50 sucrose, 92 NaCl, 15 D-Glucose, 26 NaHCO.sub.3, 5 KCl, 1.25 NaH.sub.2PO.sub.4, 0.5 CaCl.sub.2, 7 MgSO.sub.4, 1 kynurenic acid, and bubbled with 5% CO.sub.2/95% O.sub.2. The meninges, dura, and dorsal and ventral roots can then removed from the lumbar region of the spinal cord under a dissecting microscope. The cleaned lumbar region of the spinal cord may be glued to the vibratome stage and immediately immersed in ice cold, bubbled, sucrose solution. For current-clamp recordings, 300 to 350 m parasagittal slices can be cut to preserve the dendritic arbour of lamina I neurons, while 350 to 400 m transverse slices can be prepared for voltage-clamped Nav channel recordings. Slices may be allowed to recover for 1 hour at 35 C. in Ringer solution containing (in mM): 125 NaCl, 20 D-Glucose, 26 NaHCO.sub.3, 3 KCl, 1.25 NaH.sub.2PO.sub.4, 2 CaCl.sub.2, 1 MgCl.sub.2, 1 kynurenic acid, 0.1 picrotoxin, bubbled with 5% CO.sub.2/95% O.sub.2. The slice recovery chamber can then returned to room temperature (20 to 22 C.) for recordings.

[0251] Neurons may be visualized using IR-DIC optics (Zeiss Axioskop 2 FS plus, Gottingen, Germany), and neurons from lamina I and the outer layer of lamina II can be selected based on their location relative to the substantia gelatinosa layer. Neurons can be patch-clamped using borosilicate glass patch pipettes with resistances of 3 to 6 M. Current-clamp recordings of lamina I/II neurons in the intact slice, the external recording solution was the above Ringer solution, while the internal patch pipette solution contained (in mM): 140 KGluconate, 4 NaCl, 10 HEPES, 1 EGTA, 0.5 MgCl.sub.2, 4 MgATP, 0.5 Na.sub.2GTP, adjusted to pH 7.2 with 5 M KOH and to 290 mOsm with D-Mannitol (if necessary). Tonic firing neurons can be selected for current-clamp experiments, while phasic, delayed onset and single spike neurons may be discarded (22). Recordings can be digitized at 50 kHz and low-pass filtered at 2.4 kHz.

[0252] hERG K.sup.+ Channel Activity

[0253] In addition to being able to modulate a particular voltage-gated ion channel, e.g. a sodium channel, it may be desirable that the compound has very low activity with respect to the hERG K.sup.+ channel, which is expressed in the heart: compounds that block this channel with high potency may cause reactions which are fatal. See, e.g., Bowlby et al., hERG (KCNH.sub.2 or K.sub.V11.1 K.sup.+ Channels: Screening for Cardiac Arrhythmia Risk, Curr. Drug Metab. 9(9):965-70 (2008)). Thus, for a compound that modulates sodium channel activity, it may also be shown that the hERG K.sup.+ channel is not inhibited or only minimally inhibited as compared to the inhibition of the primary channel targeted. Similarly, it may be desirable that the compound does not inhibit cytochrome p450, an enzyme that is required for drug detoxification. Such compounds may be particularly useful in the methods described herein.

[0254] Compounds can be tested using a standard electrophysiological assay (Kiss et al., Assay & Drug Development Technologies, 1:1-2, 2003; Bridgland-Taylor et al., Journal of Pharmacological and Toxicological Methods, 54:189-199, 2006). For example, compounds can be tested at 3 M using IonWorks, and the percent inhibition of the peak of the slowly deactivating hERG tail current can be used to assess the affinity.

Pharmacokinetic Parameters

[0255] Preliminary exposure characteristics of the compounds can be evaluated using, e.g., an in vivo Rat Early Pharmacokinetic (EPK) study design to show bioavailability. For example, Male Sprague-Dawley rats can be dosed via oral (PO) gavage in a particular formulation. Blood samples can then be collected from the animals at 6 timepoints out to 4 hours post-dose. Pharmacokinetic analysis can then performed on the LC-MS/MS measured concentrations for each timepoint of each compound.

Pharmaceutical Compositions

[0256] For use as treatment of human and animal subjects, the compounds of the invention can be formulated as pharmaceutical or veterinary compositions. Depending on the subject to be treated, the mode of administration, and the type of treatment desirede.g., prevention, prophylaxis, or therapythe compounds are formulated in ways consonant with these parameters. A summary of such techniques is found in Remington: The Science and Practice of Pharmacy, 21.sup.st Edition, Lippincott Williams & Wilkins, (2005); and Encyclopedia of Pharmaceutical Technology, eds. J. Swarbrick and J. C. Boylan, 1988-1999, Marcel Dekker, New York, each of which is incorporated herein by reference.

[0257] The compounds described herein (e.g., a compound according to any of Formulas (l)-(X) or any of Compounds (1)-(92) of Table 1) may be present in amounts totaling 1-95% by weight of the total weight of the composition. The composition may be provided in a dosage form that is suitable for intraarticular, oral, parenteral (e.g., intravenous, intramuscular), rectal, cutaneous, subcutaneous, topical, transdermal, sublingual, nasal, vaginal, intravesicular, intraurethral, intrathecal, epidural, aural, or ocular administration, or by injection, inhalation, or direct contact with the nasal, genitourinary, gastrointesitnal, reproductive or oral mucosa. Thus, the pharmaceutical composition may be in the form of, e.g., tablets, capsules, pills, powders, granulates, suspensions, emulsions, solutions, gels including hydrogels, pastes, ointments, creams, plasters, drenches, osmotic delivery devices, suppositories, enemas, injectables, implants, sprays, preparations suitable for iontophoretic delivery, or aerosols. The compositions may be formulated according to conventional pharmaceutical practice.

[0258] In general, for use in treatment, the compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) may be used alone, as mixtures of two or more compounds or in combination with other pharmaceuticals. An example of other pharmaceuticals to combine with the compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) would include pharmaceuticals for the treatment of the same indication. For example, in the treatment of pain, a compound may be combined with another pain relief treatment such as an NSAID, or a compound which selectively inhibits COX-2, or an opioid, or an adjuvant analgesic such as an antidepressant. Another example of a potential pharmaceutical to combine with the compounds described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) would include pharmaceuticals for the treatment of different yet associated or related symptoms or indications. Depending on the mode of administration, the compounds will be formulated into suitable compositions to permit facile delivery. Each compound of a combination therapy may be formulated in a variety of ways that are known in the art. For example, the first and second agents of the combination therapy may be formulated together or separately. Desirably, the first and second agents are formulated together for the simultaneous or near simultaneous administration of the agents.

[0259] The compounds of the invention may be prepared and used as pharmaceutical compositions comprising an effective amount of a compound described herein (e.g., a compound according to any of Formulas (I)-(X) or any of Compounds (1)-(92) of Table 1) and a pharmaceutically acceptable carrier or excipient, as is well known in the art. In some embodiments, the composition includes at least two different pharmaceutically acceptable excipients or carriers.

[0260] Formulations may be prepared in a manner suitable for systemic administration or topical or local administration. Systemic formulations include those designed for injection (e.g., intramuscular, intravenous or subcutaneous injection) or may be prepared for transdermal, transmucosal, or oral administration. The formulation will generally include a diluent as well as, in some cases, adjuvants, buffers, preservatives and the like. The compounds can be administered also in liposomal compositions or as microemulsions.

[0261] For injection, formulations can be prepared in conventional forms as liquid solutions or suspensions or as solid forms suitable for solution or suspension in liquid prior to injection or as emulsions. Suitable excipients include, for example, water, saline, dextrose, glycerol and the like. Such compositions may also contain amounts of nontoxic auxiliary substances such as wetting or emulsifying agents, pH buffering agents and the like, such as, for example, sodium acetate, sorbitan monolaurate, and so forth.

[0262] Various sustained release systems for drugs have also been devised. See, for example, U.S. Pat. No. 5,624,677, which is herein incorporated by reference.

[0263] Systemic administration may also include relatively noninvasive methods such as the use of suppositories, transdermal patches, transmucosal delivery and intranasal administration. Oral administration is also suitable for compounds of the invention. Suitable forms include syrups, capsules, and tablets, as is understood in the art.

[0264] For administration to animal or human subjects, the dosage of the compounds of the invention may be, for example, 0.01-50 mg/kg (e.g., 0.01-15 mg/kg or 0.1-10 mg/kg). For example, the dosage can be 10-30 mg/kg.

[0265] Each compound of a combination therapy, as described herein, may be formulated in a variety of ways that are known in the art. For example, the first and second agents of the combination therapy may be formulated together or separately.

[0266] The individually or separately formulated agents can be packaged together as a kit. Non-limiting examples include, but are not limited to, kits that contain, e.g., two pills, a pill and a powder, a suppository and a liquid in a vial, two topical creams, etc. The kit can include optional components that aid in the administration of the unit dose to patients, such as vials for reconstituting powder forms, syringes for injection, customized for delivery systems, inhalers, etc. Additionally, the unit dose kit can contain instructions for preparation and administration of the compositions. The kit may be manufactured as a single use unit dose for one patient, multiple uses for a particular patient (at a constant dose or in which the individual compounds may vary in potency as therapy progresses); or the kit may contain multiple doses suitable for administration to multiple patients (bulk packaging). The kit components may be assembled in cartons, blister packs, bottles, tubes, and the like.

[0267] Formulations for oral use include tablets containing the active ingredient(s) in a mixture with non-toxic pharmaceutically acceptable excipients. These excipients may be, for example, inert diluents or fillers (e.g., sucrose, sorbitol, sugar, mannitol, microcrystalline cellulose, starches including potato starch, calcium carbonate, sodium chloride, lactose, calcium phosphate, calcium sulfate, or sodium phosphate); granulating and disintegrating agents (e.g., cellulose derivatives including microcrystalline cellulose, starches including potato starch, croscarmellose sodium, alginates, or alginic acid); binding agents (e.g., sucrose, glucose, sorbitol, acacia, alginic acid, sodium alginate, gelatin, starch, pregelatinized starch, microcrystalline cellulose, magnesium aluminum silicate, carboxymethylcellulose sodium, methylcellulose, hydroxypropyl methylcellulose, ethylcellulose, polyvinylpyrrolidone, or polyethylene glycol); and lubricating agents, glidants, and antiadhesives (e.g., magnesium stearate, zinc stearate, stearic acid, silicas, hydrogenated vegetable oils, or talc). Other pharmaceutically acceptable excipients can be colorants, flavoring agents, plasticizers, humectants, buffering agents, and the like.

[0268] Two or more compounds may be mixed together in a tablet, capsule, or other vehicle, or may be partitioned. In one example, the first compound is contained on the inside of the tablet, and the second compound is on the outside, such that a substantial portion of the second compound is released prior to the release of the first compound.

[0269] Formulations for oral use may also be provided as chewable tablets, or as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent (e.g., potato starch, lactose, microcrystalline cellulose, calcium carbonate, calcium phosphate or kaolin), or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example, peanut oil, liquid paraffin, or olive oil. Powders, granulates, and pellets may be prepared using the ingredients mentioned above under tablets and capsules in a conventional manner using, e.g., a mixer, a fluid bed apparatus or a spray drying equipment.

[0270] Dissolution or diffusion controlled release can be achieved by appropriate coating of a tablet, capsule, pellet, or granulate formulation of compounds, or by incorporating the compound into an appropriate matrix. A controlled release coating may include one or more of the coating substances mentioned above and/or, e.g., shellac, beeswax, glycowax, castor wax, carnauba wax, stearyl alcohol, glyceryl monostearate, glyceryl distearate, glycerol palmitostearate, ethylcellulose, acrylic resins, dl-polylactic acid, cellulose acetate butyrate, polyvinyl chloride, polyvinyl acetate, vinyl pyrrolidone, polyethylene, polymethacrylate, methylmethacrylate, 2-hydroxymethacrylate, methacrylate hydrogels, 1,3 butylene glycol, ethylene glycol methacrylate, and/or polyethylene glycols. In a controlled release matrix formulation, the matrix material may also include, e.g., hydrated methylcellulose, carnauba wax and stearyl alcohol, carbopol 934, silicone, glyceryl tristearate, methyl acrylate-methyl methacrylate, polyvinyl chloride, polyethylene, and/or halogenated fluorocarbon.

[0271] The liquid forms in which the compounds and compositions of the present invention can be incorporated for administration orally include aqueous solutions, suitably flavored syrups, aqueous or oil suspensions, and flavored emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil, or peanut oil, as well as elixirs and similar pharmaceutical vehicles.

[0272] Generally, when administered to a human, the oral dosage of any of the compounds of the combination of the invention will depend on the nature of the compound, and can readily be determined by one skilled in the art. Typically, such dosage is normally about 0.001 mg to 2000 mg per day, desirably about 1 mg to 1000 mg per day, and more desirably about 5 mg to 500 mg per day. Dosages up to 200 mg per day may be necessary.

[0273] Administration of each drug in a combination therapy, as described herein, can, independently, be one to four times daily for one day to one year, and may even be for the life of the patient. Chronic, long-term administration may be indicated.

[0274] The following Examples are intended to illustrate the synthesis of a representative number of compounds and the use of these compounds for the modulation of sodium channel activity. Accordingly, the Examples are intended to illustrate, but not limit the invention. Additional compounds not specifically exemplified may be synthesized using conventional methods in combination with the methods described herein.

EXAMPLES

Example 1: Synthesis

Synthesis of (R)-2-amino-N((S)-1-(3,5-bis(trifluoromethyl)phenoxy)propan-2-yl)-4-methylpentanamide

[0275] ##STR00027##

Standard conditions for amide bond formation can be used to prepare compounds described herein. For example, (R)-2-amino-N((S)-1-(3,5-bis(trifluoromethyl)phenoxy)propan-2-yl)-4-methylpentanamide can be synthesized starting from commercially available (2R)-2-[(tert-butoxycarbonyl)amino]-4-methylpentanoic acid (Compound 93) and (R)-()-2-amino-1-propanol using standard 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI) and hydroxybenzotriazole (HOBt) amide coupling conditions to yield compounds of the invention (e.g., Compound 95 of Scheme 1). Subsequent Mitsunobu coupling with 3,5-bis(trifluoromethyl)phenol can afford Compound 1 of Table 1.

Synthesis of (2R)N-(3,5-dimethyladamantan-1-yl)pyrrolidine-2-carboxamide

[0276] ##STR00028##

[0277] (2R)N-(3,5-dimethyladamantan-1-yl)pyrrolidine-2-carboxamide can be synthesized from D-proline and N-(3,5-dimethyl-1-adamantyl)-amine hydrochloride utilizing standard EDCI and HOBt amide coupling conditions as shown in Scheme 2.

[0278] Still other general procedures that can be used to obtain the compounds described herein are set forth in PCT/CA2012/000193, incorporated herein by reference.

[0279] Compounds of the invention include the following compounds listed in Table 1. Mass spectrometry can be employed with final compounds and at various stages throughout the synthesis as a confirmation of the identity of the product obtained (M+1). For the mass spectrometric analysis, samples can be prepared at an approximate concentration of 1 g/mL in acetonitrile with 0.1% formic acid. Samples can be manually infused into an Applies Biosystems API3000 triple quadrupole mass spectrometer and scanned in Q1 in the range of 50 to 700 m/z.

TABLE-US-00001 TABLE 1 No. Structure MW Name 1 [00029] 400.365 (R)-2-amino-N-((S)-1-(3,5- bis(trifluoromethyl)phenoxy)propan- 2-yl)-4-methylpentanamide 2 [00030] 292.423 (2R)-2-amino-N-(1-(2,6- dimethylphenoxy)propan-2-yl)-4- methylpentanamide 3 [00031] 292.423 (2S)-2-amino-N-(1-(2,6- dimethylphenoxy)propan-2-yl)-4- methylpentanamide 4 [00032] 462.436 2-amino-N-((S)-2-(3,5- bis(trifluoromethyl)phenoxy)-1- phenylethyl)-4- methylpentanamide 5 [00033] 400.365 2-amino-N-((R)-1-(3,5- bis(trifluoromethyl)phenoxy)propan- 2-yl)-4-methylpentanamide 6 [00034] 400.365 (2R)-2-amino-N-(1-(3,5- bis(trifluoromethyl)phenoxy)propan- 2-yl)-4-methylpentanamide 7 [00035] 386.338 (2S,3S)-2-amino-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl)- 3-methylpentanamide 8 [00036] 398.349 (1R,2S)-2-amino-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl) cyclohexane-1-carboxamide 9 [00037] 406.328 (S)-2-amino-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl)- 2-phenylacetamide 10 [00038] 400.365 2-amino-N-((S)-1-(3,5- bis(trifluoromethyl)phenoxy)propan- 2-yl)-4-methylpentanamide 11 [00039] 370.295 (R)-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl) pyrrolidine-2-carboxamide 12 [00040] 278.396 (2R)-2-amino-N-(1-(2,6- dimethylphenoxy)propan-2-yl)-3- methylbutanamide 13 [00041] 400.365 (R)-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl)- 4-methyl-2- (methylamino)pentanamide 14 [00042] 370.295 N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl) pyrrolidine-2-carboxamide 15 [00043] 276.38 (2S)-N-(1-(2,6- dimethylphenoxy)propan-2- yl)pyrrolidine-2-carboxamide 16 [00044] 350.358 (R)-N-(2-(3-fluoro-5- (trifluoromethyl)phenoxy)ethyl)-4- methyl-2- (methylamino)pentanamide 17 [00045] 236.315 2-amino-N-(1-(2,6- dimethylphenoxy)propan-2- yl)acetamide 18 [00046] 350.358 (S)-3-amino-N-(2-(3-fluoro-5- (trifluoromethyl)phenoxy)ethyl)-5- methylhexanamide 19 [00047] 336.331 (2R,3R)-2-amino-N-(2-(3-fluoro- 5-(trifluoromethyl)phenoxy)ethyl)- 3-methylpentanamide 20 [00048] 320.288 (R)-N-(2-(3-fluoro-5- (trifluoromethyl)phenoxy)ethyl) pyrrolidine-2-carboxamide 21 [00049] 356.268 1-amino-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl) cyclopropane-1-carboxamide 22 [00050] 320.288 (S)-N-(2-(3-fluoro-5- (trifluoromethyl)phenoxy)ethyl) pyrrolidine-2-carboxamide 23 [00051] 322.304 (R)-2-amino-N-(2-(3-fluoro-5- (trifluoromethyl)phenoxy)ethyl)-3- methylbutanamide 24 [00052] 412.376 2-(1-aminocyclohexyl)-N-(2-(3,5- bis(trifluoromethyl)phenoxy)ethyl) acetamide 25 [00053] 400.321 (R)-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl) morpholine-2-carboxamide 26 [00054] 398.349 (S)-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl) piperidine-2-carboxamide 27 [00055] 452.373 (S)-2-amino-N-(3-(3,5- bis(trifluoromethyl)phenoxy) propyl)-3-(3- fluorophenyl)propanamide 28 [00056] 412.376 N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl)- 2-methylpiperidine-2- carboxamide 29 [00057] 384.322 (R)-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl) pyrrolidine-2-carboxamide 30 [00058] 358.284 (S)-2-amino-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl) propanamide 31 [00059] 414.392 (S)-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl)- 4-methyl-2- (methylamino)pentanamide 32 [00060] 344.257 2-amino-N-(3-(3,5- bis(trifluoromethyl)phenoxy)propyl) acetamide 33 [00061] 375.513 N-(1-(2,6- dimethylphenoxy)propan-2-yl)- 2,2-dimethyl-4-oxo-4-(piperazin- 1-yl)butanamide 34 [00062] 347.459 N1-(1-(2,6- dimethylphenoxy)propan-2-yl)- N3-(piperidin-4-yl)malonamide 35 [00063] 319.405 N-(1-(2,6- dimethylphenoxy)propan-2-yl)-2- (2-oxopiperazin-1-yl)acetamide 36 [00064] 333.432 N-(1-(2,6- dimethylphenoxy)propan-2-yl)-3- (2-oxopiperazin-1- yl)propanamide 37 [00065] 347.459 N-(1-(2,6- dimethylphenoxy)propan-2-yl)-2- methyl-2-(2-oxopiperazin-1- yl)propanamide 38 [00066] 462.436 (2R)-2-amino-N-(2-(3,5- bis(trifluoromethyl)phenoxy)-1- phenylethyl)-4- methylpentanamide 39 [00067] 327.23 (S)-3-(2-aminoethyl)-5,7- bis(trifluoromethyl)-3,4- dihydroquinoxalin-2(1H)-one 40 [00068] 313.203 (S)-3-(aminomethyl)-5,7- bis(trifluoromethyl)-3,4- dihydroquinoxalin-2(1H)-one 41 [00069] 312.171 5-(3,5- bis(trifluoromethyl)phenyl) imidazolidine-2,4-dione 42 [00070] 326.198 5-(3,5-bis(trifluoromethyl)phenyl)- 5-methylimidazolidine-2,4-dione 43 [00071] 276.424 (2R)-N-(3,5-dimethyladamantan- 1-yl)pyrrolidine-2-carboxamide 44 [00072] 262.397 (R)-N-(adamantan-1- ylmethyl)pyrrolidine-2- carboxamide 45 [00073] 248.37 (S)-N-(adamantan-1- yl)pyrrolidine-2-carboxamide 46 [00074] 250.386 3-amino-N-(3,5- dimethyladamantan-1- yl)propanamide 47 [00075] 239.198 2-(2-oxopiperazin-1-yl)-N-(2,2,2- trifluoroethyl)acetamide 48 [00076] 275.327 (S)-N-(2-(5-fluoro-1H-indol-3- yl)ethyl)pyrrolidine-2- carboxamide 49 [00077] 355.284 (R)-1-(3,5- bis(trifluoromethyl)phenyl)-3- (pyrrolidin-2-ylmethyl)urea 50 [00078] 345.322 1-(1-acetylpiperidin-4-yl)-3-(4- (trifluoromethoxy)phenyl)urea 51 [00079] 373.302 (S)-1-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-2- phenylethan-1-amine 52 [00080] 385.313 2-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-2,3- dihydro-1H-inden-2-amine 53 [00081] 387.329 (S)-1-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-3- phenylpropan-2-amine 54 [00082] 393.717 (S)-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)(4- chlorophenyl)methanamine 55 [00083] 391.293 (R)-1-(4,6-bis(trifluoromethyl)- 1H-benzo[d]imidazol-2-yl)-2-(3- fluorophenyl)ethan-1-amine 56 [00084] 405.32 (R)-1-(4,6-bis(trifluoromethyl)- 1H-benzo[d]imidazol-2-yl)-3-(4- fluorophenyl)propan-2-amine 57 [00085] 359.275 (R)-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2- yl)(phenyl)methanamine 58 [00086] 377.266 (S)-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)(4- fluorophenyl)methanamine 59 [00087] 371.286 2-(isoindolin-1-y)-4,6- bis(trifluoromethyl)-1H- benzo[d]imidazole 60 [00088] 394.321 1-(2-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)propan-2- yl)piperazin-2-one 61 [00089] 394.321 3-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-1- (piperazin-1-yl)propan-1-one 62 [00090] 422.375 3-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-3-methyl- 1-(piperazin-1-yl)butan-1-one 63 [00091] 309.167 1-((6-bromo-1H- benzo[d]imidazol-2- yl)methyl)piperazin-2-one 64 [00092] 294.306 1-(2-(4,6-difluoro-1H- benzo[d]imidazol-2-yl)propan-2- yl)piperazin-2-one 65 [00093] 408.348 1-(2-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-2- methylpropyl)piperazin-2-one 66 [00094] 294.306 3-(4,6-difluoro-1H- benzo[d]imidazol-2-yl)-1- (piperazin-1-yl)propan-1-one 67 [00095] 322.36 3-(4,6-difluoro-1H- benzo[d]imidazol-2-yl)-3-methyl- 1-(piperazin-1-yl)butan-1-one 68 [00096] 294.306 1-(3-(4,6-difluoro-1H- benzo[d]imidazol-2- yl)propyl)piperazin-2-one 69 [00097] 394.321 1-(3-4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2- yl)propyl)piperazin-2-one 70 [00098] 308.333 1-(2-(4,6-difluoro-1H- benzo[d]imidazol-2-yl)-2- methylpropyl)piperazin-2-one 71 [00099] 490.887 (R)-2-amino-N-((6-(3-chloro-4- fluorophenyl)-1H- benzo[d]imidazol-2-yl)methyl)-3- (3- (trifluoromethyl)phenyl)propanamide 72 [00100] 541.369 tert-butyl (R)-(1-(((6-bromo-1H- benzo[d]imidazol-2- yl)methyl)amino)-1-oxo-3-(3- (trifluoromethyl)phenyl)propan-2- yl)carbamate 73 [00101] 598.47 tert-butyl (R)-(1-(((4,6- bis(trifluoromethyl)-1H- benzo[d]imidazol-2- yl)methyl)amino)-1-oxo-3-(3- (trifluoromethyl)phenyl)propan-2- yl)carbamate 74 [00102] 441.252 (R)-2-amino-N-((6-bromo-1H- benzo[d]imidazol-2-yl)methyl)-3- (3- (trifluoromethyl)phenyl)propanamide 75 [00103] 498.353 (R)-2-amino-N-((4,6- bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)methyl)-3- (3- (trifluoromethyl)phenyl)propanamide 76 [00104] 591.004 tert-butyl (R)-(1-(((6-(3-chloro-4- fluorophenyl)-1H- benzo[d]imidazol-2- yl)methyl)amino)-1-oxo-3-(3- (trifluoromethyl)phenyl)propan-2- yl)carbamate 77 [00105] 410.364 N-((4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)methyl)-2- (tert-butylamino)-N- methylacetamide 78 [00106] 300.204 2-amino-N-(3,5- bis(trifluoromethyl)benzyl)acetamide 79 [00107] 386.294 (R)-2-acetamido-N-(3,5- bis(trifluoromethyl)benzyl)-3- methoxypropanamide 80 [00108] 401.309 (R)-2-amino-N-(2-((3,5- bis(trifluoromethyl)benzyl)amino)- 2-oxoethyl)-3- methoxypropanamide 81 [00109] 360.337 (R)-2-(2-oxopiperazin-1-yl)-N-(1- (5-(2,2,2-trifluoroethoxy)pyridin- 2-yl)ethyl)acetamide 82 [00110] 317.312 (S)-N-((R)-1-(5-(2,2,2- trifluoroethoxy)pyridin-2- yl)ethyl)pyrrolidine-2- carboxamide 83 [00111] 317.312 (R)-N-((R)-1-(5-(2,2,2- trifluoroethoxy)pyridin-2- yl)ethyl)pyrrolidine-2- carboxamide 84 [00112] 337.269 (R)-2-(piperidin-2-yl)-5,7- bis(trifluoromethyl)-1H- benzo[d]imidazole 85 [00113] 339.241 (3S,5S)-5-(5,7- bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)pyrrolidin- 3-ol 86 [00114] 414.287 2-(5-(4-fluorophenyl)-1H-pyrazol- 3-yl)-4,6-bis(trifluoromethyl)-1H- benzo[d]imidazole 87 [00115] 394.321 2-(4,6-bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)-N- (piperidin-4-yl)acetamide 88 [00116] 337.269 (S)-2-(pyrrolidin-2-ylmethyl)-4,6- bis(trifluoromethyl)-1H- benzo[d]imidazole 89 [00117] 294.306 2-(4,6-difluoro-1H- benzo[d]imidazol-2-yl)-N- (piperidin-4-yl)acetamide 90 [00118] 394.321 1-(4-aminopiperidin-1-yl)-2-(4,6- bis(trifluoromethyl)-1H- benzo[d]imidazol-2-yl)ethan-1- one 91 [00119] 326.242 1-(3,5- bis(trifluoromethyl)benzyl)piperazin- 2-one 92 [00120] 412.332 (R)-4-acetyl-1-(3,5- bis(trifluoromethyl)benzyl)-3- (methoxymethyl)piperazin-2-one

Example 2. Ion Channel Activity Assays

[0280] The compounds described herein were assayed for the ability to block Nav1.7. These compounds can also be assayed for modulation of, e.g., voltage gated sodium channels (e.g., other Na.sup.+ channel isoforms or Ca.sup.2+ channels such as Ca.sub.V3.2 T-type channels). Exemplary methods are described herein, but additional methods are known in the art.

Cell Generation and Maintenance

[0281] The generation of a HEK 293F cell line stably expressing human Nav1.7/Navp1 was achieved by co-transfecting human SCN9A and human SCN1B cDNAs, subcloned into plasmid vectors, utilizing standard transfection techniques. Clones were selected using appropriate selection agents (0.3 mg/mL Zeocin and 0.8 mg/mL Geneticin) and maintained in Dulbecco's Modified Eagle medium, 10% fetal bovine serum, 1% non-essential amino acids to 80% confluence at 37 C. in a humidified incubator with 95% atmosphere and 5% CO.sub.2.

Nav1.5 Assay

[0282] Inhibition of the TTX-resistant Nav1.5 sodium channel, a key cardiac ion channel, can have profound effects on the duration and amplitude of the cardiac action potential and can result in arrhythmias and other heart malfunctions. To assess the potential cardiac liability of compounds at an early stage in the drug discovery process, a Nav1.5 sodium channel screening assay can be performed on Molecular Device's PatchXpress automated electrophysiology platform. Under voltage-clamp conditions, Nav1.5 currents can be recorded from HEK cells expressing the human Nav1.5 channel in the absence and presence of increasing concentrations of the test compound to obtain an IC.sub.50 value. The external recording solution can contain (in mM): 90 TEACI, 50 NaCl, 1.8 CaCl, 1 MgCl.sub.2, 10 HEPES, 10 glucose, adjusted to pH 7.4 with TEA-OH and to 300 mOsm with sucrose (if necessary), while the internal patch pipette solution contained (in mM): 129 CsF, 2 MgCl.sub.2, 11 EGTA, 10 HEPES, 3 Na.sub.2ATP adjusted to pH 7.2 with CsOH and to 290 mOsm with sucrose (if necessary). Nav1.5 channel currents can be evoked using a cardiac action potential waveform at 1 Hz, digitized at 31.25 kHz and low-pass filtered at 12 kHz.

Assessment of Nav1.7 Activity

[0283] On the day of each experiment, cells that were grown to 80% confluence in a T75 flask were harvested for use on PatchXpress (Molecular Devices, CA, USA). Following a recovery period at 37 C. in a humidified incubator with 95% atmosphere and 5% CO.sub.2 in Dulbecco's Modified Eagle Medium, the media was replaced with an external recording solution containing (in mM): 90 TEACI, 50 NaCl, 1.8 CaCl.sub.2, 1 MgCl.sub.2, 10 HEPES, 10 glucose, adjusted to pH 7.4 with TEAOH and 300 mOsm with sucrose. The internal recording solution contained (in mM): 129 CsF, 2 MgCl.sub.2, 11 EGTA, 10 HEPES, 6 NaCl, 3 Na.sub.2ATP adjusted to pH 7.2 with CsOH and 280 mOsm with sucrose. The automated liquid handling facility of PatchXpress dispensed cells and added compound. Modulation of Nav1.7 channels by compounds was assessed by promoting the channels into the inactivated state using a conditioning voltage pulse of variable amplitude, followed by a brief hyperpolarizing pulse with a subsequent depolarized voltage step to measure the current amplitude in the presence and absence of compound. Compounds were assayed at 10 M. Based upon this Patch express protocol, four electrophysiological parameters were measured relative to a 0.2% DMSO vehicle control (Table 2). This first data column describes compound induced shifts in the voltage dependence of slow inactivation (Table 2: hNav1.7: Reduction in current at 20 mV) at which 50% of the channels were inactivated. The second data column describes the change in the population of Nav1.7 channels undergoing fast inactivation before and after a 30 sec conditioning voltage pulse at 20 mV (Table 2: hNav1.7: Reduction in current at 20 mV (normalized data). The ratio of these currents elicited by a hyperpolarizing pulse before and after preconditioning allows the determination of the fraction of Nav1.7 channels in the slow inactivated state. The third data column displays the voltage dependence of activation (Table 2: hNav1.7: Voltage dependence of activation). Lastly, the fourth data column describes the voltage dependence of fast inactivation in which 50% of the channels were inactivated (Table 2: hNav1.7: Voltage dependence of fast inactivation).

[0284] In some cases, the potency of compounds was measured using either the Patchliner automated patch clamp platform (Nanion) or manual patch clamp techniques. Both approaches allowed the compounds to be characterized based upon the ability of a compound to modulate use- and/or state-dependence. The potency data is tabulated in Table 3 and is represented by eight data fields. The first four fields represent potency data measured with the Patchliner automated platform under varying use- and state-dependent electrophysiology protocols similar to the Patch express protocols detailed above. The first data column describes the potency of compounds when the Nav1.7 channel is being repetitively activated at a 7 Hz hyperpolarization frequency (Table 3: hNav1.7: IC50 of inward current block at 7 Hz, Automated patchclamp). The second data column represents the potency at which 50% of the initial hyperpolarization pulse is inhibited by the compounds (Table 3: hNav1.7: IC50 of P1 block, Automated patchclamp). The third data column details the potency of compounds in their ability to block 50% of Nav1.7 channels when these channels are induced into the slow inactivated state (Table 3: hNav1.7: IC50 of slow inactivation block, Automated patchclamp). The fourth data column shows potency data at which 50% of channel activity is blocked when repetitively activated at a 0.25 Hz hyperpolarizing frequency (Table 3: hNav1.7: IC50 of inward current block at 0.25 Hz, Automated patchclamp). The next three data fields describe the data generated from manual patchclamp electrophysiology measurements using similar methods to those employed for automated patchclamp studies. The fifth and sixth data columns demonstrate the potency at which 50% of channel activity was inhibited when repetitively activated with a 7 Hz or 0.25 Hz hyperpolarization frequency, respectively (Table 3: hNav1.7: IC50 of inward current block at 7 Hz, Manual patchclamp)(hNav1.7: IC50 of inward current block at 0.25 Hz, Manual patchlamp). The seventh column shows the potency of certain compounds which block 50% channel activity when the Nav1.7 channel is in the slow inactivated state (hNav1.7: IC50 of slow inactivation block, Manual patchclamp). The last column characterizes the state-dependence of compound inhibition. Compounds that maintain the greatest potency for the slow inactivated state over fast inactivated or tonic inhibition at 0.25 Hz are characterized as state dependent, blocker of slow inactivation.

TABLE-US-00002 TABLE 2 hNav1.7: hNav1.7: hNav1.7: hNav1.7: Shift in Reduction Voltage Voltage voltage in current dependence dependence dependence of at 20 mV of of fast inactivation (normalized activation inactivation Compound (mV) data) (mV) (mV) # Delta Vhalf Delta Ratio VDEP VDEP 1 20.90 0.30 8.60 6.80 2 32.20 0.29 10.00 8.20 3 28.00 0.28 8.10 7.40 4 31.10 0.27 5.80 11.50 5 25.20 0.26 4.60 6.30 6 32.70 0.25 4.80 6.20 7 21.40 0.24 8.10 6.60 8 16.40 0.23 7.80 6.80 9 18.30 0.21 8.10 7.90 10 31.40 0.20 3.70 3.50 11 19.70 0.20 5.00 3.90 12 25.70 0.19 7.30 4.30 13 23.80 0.17 5.90 4.00 14 25.30 0.17 4.00 1.10 15 20.60 0.16 6.00 4.90 43 8.50 0.12 11.40 5.70 16 14.70 0.11 2.80 2.60 44 5.40 0.11 13.20 6.00 17 12.40 0.10 5.80 5.90 18 11.90 0.09 2.60 3.90 39 4.90 0.08 7.40 3.10 19 10.00 0.08 8.00 3.50 45 6.20 0.07 5.10 7.00 46 1.70 0.04 7.90 4.50 40 3.90 0.02 6.60 2.60 47 2.50 0.02 8.90 4.40 48 1.80 0.01 4.80 3.00 20 7.20 0.01 6.80 4.40 21 4.20 0.00 5.20 10.40 22 7.00 0.06 6.50 1.80 33 5.30 0.07 8.70 6.00 34 2.30 0.03 6.30 5.10 41 2.80 0.00 9.00 5.30 42 0.50 0.02 6.60 2.50 49 6.40 0.18 10.20 7.80 50 0.30 0.02 8.30 2.10 37 5.00 0.09 9.00 6.30 35 3.00 0.06 7.40 4.40 36 2.90 0.04 12.90 5.00 38 33.7 0.34 11.5 15.3 51 20.8 0.35 9.5 11.5 52 14.9 0.28 7.2 8.2 53 7.2 0.28 8.2 3.9 54 27.4 0.26 10 8.6 55 15.1 0.26 8.6 6.2 56 16.8 0.21 14.4 3.3 57 10.4 0.21 4.7 4.8 58 8.6 0.21 4 4.9 59 12.8 0.2 9 5.9 60 9.2 0.19 8.3 3.8 61 9.2 0.19 11.3 5.1 62 12.5 0.19 7.4 3.8 63 9.7 0.17 8.1 6.4 64 5.4 0.16 7.1 5.9 65 3.5 0.16 8.1 6.2 66 12.0 0.14 14.5 6.9 67 7.8 0.13 9.7 7.6 68 11.4 0.1 11.6 4.9 69 7.5 0.09 9.2 4.9 70 4.6 0.08 5.3 5.7 71 8.5 0.07 10.5 6.3 72 6.7 0.07 3.3 7.3 73 3.7 0.07 12.5 5.4 74 7.4 0.07 3.7 8.8 75 2.3 0.06 15.4 3.7 76 0.3 0.06 11.4 3.9 77 0.3 0.06 2.2 5 78 4.2 0.04 10.5 4.6 79 5.8 0.04 15.2 7.9 80 7.2 0.03 9.3 3.8 81 2.8 0.02 10.3 5 82 2.5 0.02 5.6 8.7 83 1.5 0.01 3.1 0.5 84 0 0.02 6.7 2.4 85 0.3 0.03 3.4 3.2 89 3.6 0.01 10.6 4.4 90 2.3 0.01 2.9 0.1 91 3.1 0.01 5 4.1 92 2.2 0.01 7.1 3.9

TABLE-US-00003 TABLE 3 Nav1.7 IC50 Nav1.7 IC50 Nav1.7 IC50 INWARD Nav1.7 IC50 INWARD INWARD Nav1.7 IC50 CURRENT Nav1.7 SLOW CURRENT CURRENT SLOW BLOCK (nM) IC50 P1 INACTIVATION BLOCK (nM) BLOCK (nM) INACTIVATION (7 Hz, BLOCK (nM) BLOCK (nM) (0.25 Hz, (7 Hz, BLOCK Electrophysio- Automated (Automated (Automated Automated Manual (nM) (Manual logical No. Patchclamp) Patchclamp) Patchclamp) Patchclamp) Patchclamp) Patchclamp) Characterization 1 15500.00 2580.00 568.00 STATE- DEPENDENT, BLOCKER OF SLOW INACTIVATION 6 1660.00 12700.00 2770.00 10 1890.00 11500.00 4120.00 STATE- DEPENDENT, BLOCKER OF SLOW INACTIVATION 16 9620.00 15000.00 8120.00 15000.00 23200.00 3500.00 STATE- DEPENDENT, BLOCKER OF SLOW INACTIVATION 38 10300 5320 436 STATE- DEPENDENT, BLOCKER OF SLOW INACTIVATION 54 2890 312 STATE- DEPENDENT, BLOCKER OF SLOW INACTIVATION 75 15000 15000 15000

Example 3. Pain Test Assays

[0285] As discussed above, the compounds described herein can be tested for efficacy in any standard animal model of pain, wherein the animal's response to the application or injection of a chemical irritant to the skin, muscle joints, or internal organs is measured.

[0286] The formalin test in rats was performed as previously described (McNamara, 2007. Proc. Natl. Acad. Sci., vol 104, page 13525) using an automated flinch-detecting system (T. Yaksh, University of California at San Diego, La Jolla, Calif.). On the day of testing, a small metal band (0.5 g) was loosely placed around the right hind paw of a male Sprague-Dawley rat (average weight, 250 g). The rats were allowed to acclimate to a Plexiglas chamber for at least 30 min before testing. Formalin was then injected (50 l of 2.5% formalin, diluted in saline) into the dorsal surface of the right hind paw of the rat, and the animal was put into a chamber of the automated formalin apparatus where movement of the formalin-injected paw was recorded. The number of paw flinches per minute was tallied for the next 60 minutes. The time interval phases were defined as follows: Phase I (0-9 mins), Phase II (10-60 mins), Phase IIA (10-40 mins), and Phase IIB (41-60 mins). The following compounds were administered 1 hour prior to formalin administration. Compound 52 from Table 1 was administered by oral gavage in 4% DMSO, 10% Solutol, 86% H.sub.2O. Gabapentin was administered subcutaneously in 0.9% NaCl (aq). The results are shown in Table 4.

TABLE-US-00004 TABLE 4 Treatment Phase 1 Phase 2a Phase 2b Total Phase 2 Vehicle 301 91 966 217 352 202 1318 352 Compound 52 3 mg/kg 345 75 988 139 377 79 1365 174 Compound 52 10 mg/kg 315 58 758 199* 204 66* 962 189* Compound 52 30 mg/kg 333 75 706 261** 147 101* 853 259* Gabapentin 100 mg/kg SC 320 58 486 202*** 77 47*** 562 213** *p < 0.05; **p < 0.01; ***p < 0.001; 1-tailed t-test versus vehicle

Other Embodiments

[0287] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure come within known or customary practice within the art to which the invention pertains and may be applied to the essential features hereinbefore set forth.

[0288] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.