Use of KOR agonist in combination with MOR agonist in preparing drug for treating pain

Abstract

Disclosed is the use of a KOR agonist in combination with a MOR agonist in preparing a drug for treating pain. The KOR agonist is selected from a compound as shown in the general formula (I), and the MOR agonist is selected from a compound as shown in the general formula (II), wherein the definitions of each substituent in the general formula (I) and (II) are the same as defined in the description. ##STR00001##

Claims

1. A method of alleviating and/or treating pain in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a κ opioid receptor (KOR) agonist and μ opioid receptor (MOR) agonist, wherein the KOR agonist is a compound of formula (I): ##STR00032## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, wherein: G is selected from the group consisting of O, —NR.sup.4 and —CR.sup.5R.sup.6; R.sup.1 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7 and —NR.sup.8R.sup.9, wherein the alkyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.2 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR.sup.7, —C(O)R.sup.7 and —C(O)OR.sup.7, wherein the alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.3 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR.sup.7, —C(O)R.sup.7 and —C(O)OR.sup.7, wherein the alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.4 is selected from the group consisting of hydrogen, alkyl, haloalkyl, cycloalkyl, alkoxy, hydroxyalkyl, amino, alkoxycarbonyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7, —NR.sup.8R.sup.9 and —NHC(O)NR.sup.8R.sup.9, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.5 and R.sup.6 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7, —NR.sup.8R.sup.9 and —NHC(O)NR.sup.8R.sup.9, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.7 is selected from the group consisting of hydrogen, alkyl, amino, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.8 and R.sup.9 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; and m is 0, 1 or 2.

2. The method according to claim 1, wherein the KOR agonist is a compound of formula (I-B): ##STR00033## or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

3. The method according to claim 1, wherein the KOR agonist is a compound of formula (I-C): ##STR00034## or diastereomer thereof, or a mixture thereof, or a pharmaceutically accepta 1e salt thereof.

4. The method according to claim 1, wherein the KOR agonist is selected from the group consisting of: ##STR00035## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

5. The method according to claim 1, wherein the MOR agonist is a compound of formula (II): ##STR00036## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, wherein: ring A is selected from the group consisting of cycloalkyl and heterocyclyl; R is selected from the group consisting of aryl and heteroaryl, wherein the aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5; each R.sup.1 is identical or different and each is independently selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5, wherein the alkyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; each R.sup.2 is identical or different and each is independently selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, oxo, alkenyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5, wherein the alkyl, alkoxy, alkenyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of deuterium, alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; or two R.sup.2 are taken together to form a cycloalkyl or heterocyclyl, wherein the cycloalkyl or heterocyclyl is optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.3 is selected from the group consisting of hydrogen, alkyl, deuterated alkyl, amino, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.4 and R.sup.5 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; p and q are each independently 0, 1, 2, 3 or 4; and m is 0, 1 or 2.

6. The method according to claim 5, wherein the MOR agonist is a compound of formula (II-B): ##STR00037## or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

7. The method according to claim 5, wherein the MOR agonist is selected from the group consisting of: ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

8. The method according to claim 1, wherein the MOR agonist is selected from the group consisting of dihydromorphone hydrochloride, morphine, oxycodone, buprenorphine, sufentanil, fentanyl, trifentanil, remifentanil, tapentadol, NKTR-181, eluxadoline, benzohydrocodone, loperamide, oliceridine, samidorphan, cebranopadol, tapentadol, methadone, tramadol, TV-46763, hydrocodone, dexketoprofen, oxymorphone, MH-200, levorphanol, Sedatin, desmethyl tramadol, IBCh-07, HS-731, Cyt-1010, trimebutine 3-thiocarbamoyl-benzenesulfonate, thienorphine, trimebutine, TRV-734, TRK-130, hydromorphone, hydromorphone prodrug, EU-178, OREX-1038, AIKO-152, TH-030418, CC-408, XE-440, CYX-6, Org-41793, DPI-125, KN-203, JVA-3025, AT-121, VRP-26, endomorphin, NKTR-196, NKTR-174, NKTR-192, NESS-117-OPB, SYK-524, HS-731, HS-198, Dmt-Tic analogue, endorphin 1 derivative, MMP-2200, SEO-16, TLI-0326, BU-08028, BU-08073, TLI-1186, KIN-3031, Neo-1509, GRT-6006, MCP-201, NE-2, MGM-9, EN-3231, NRP-290, NS-7051, CDS-PM-101, frakefamide, BCH-2687, SS-620, VANH-36, 443C81, OHM-329, dermorphin tetrapeptide analogue, sameridine, OHM-3507, SEP-130551, BW-2378W92, sulfazocine, Z-4349, RP-63494, BCH-150, CP-840, and CP-0719.

9. The method according to claim 1, wherein the pain is selected from the group consisting of acute pain and chronic pain, and the chronic pain is selected from the group consisting of headache, maxillofacial pain, cervical and occipital pain, neck and shoulder pain, upper limb pain, chest pain, abdominal pain, lumbocrural pain, genital tract pain, urinary tract pain and dysmenorrhea.

10. The method according to claim 1, wherein the pain is selected from the group consisting of traumatic pain, inflammatory pain, ischemic pain, pain caused by metabolic diseases, neuropathic pain, pain caused by tissue and organ malformation, labor pain and pain caused by malignant proliferative diseases; the traumatic pain is selected from the group consisting of pain caused by surgery, fracture pain, burn pain, abdominal traumatic pain, spinal traumatic pain, chest traumatic pain and post-traumatic headache; the inflammatory pain is selected from the group consisting of inflammatory headache, tissue inflammatory pain, organ and gland inflammatory pain and vascular inflammatory pain; the ischemic pain is selected from the group consisting of ischemic headache, limb ischemic pain, tissue ischemic pain, and organ and gland ischemic pain; the pain caused by metabolic diseases is selected from the group consisting of pain caused by gout and pain caused by diabetes; the neuropathic pain is selected from the group consisting of phantom limb pain, stump pain, burning neuralgia, postherpetic neuralgia, sympathetic-related pain, pain caused by burning foot syndrome, folic acid deficiency peripheral neuralgia, vitamin B12 deficiency peripheral neuralgia, vitamin B1 deficiency multiple neuralgia and leprosy neuralgia; the pain caused by malignant proliferative diseases is pain caused by tumors.

11. The method according to claim 10, wherein the pain is a moderate to severe pain selected from the group consisting of traumatic pain, labor pain, pain caused by tumors and inflammatory pain.

12. The method according to claim 11, wherein the moderate to severe pain is not sensitive to non-opioid analgesics.

13. The method according to claim 1, wherein the combination further comprises a third component selected from the group consisting of an opioid, glucocorticoid, non-steroidal anti-inflammatory drug, anesthetic, local anesthetic, anti-depressant, calcium channel antagonist, anti-convulsant, adrenal beta receptor blocker, and anesthesia inducer.

14. A pharmaceutical composition, comprising a MOR agonist and a KOR agonist, and one or more pharmaceutically acceptable excipients, diluents or carriers, wherein the KOR agonist is a compound of formula (I): ##STR00043## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, wherein: G is selected from the group consisting of O, —NR.sup.4 and —CR.sup.5R.sup.6; R.sup.1 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7 and —NR.sup.8R.sup.9, wherein the alkyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.2 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR.sup.7, —C(O)R.sup.7 and —C(O)OR.sup.7, wherein the alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.3 is selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR.sup.7, —C(O)R.sup.7 and —C(O)OR.sup.7, wherein the alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.4 is selected from the group consisting of hydrogen, alkyl, haloalkyl, cycloalkyl, alkoxy, hydroxyalkyl, amino, alkoxycarbonyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7, —NR.sup.8R.sup.9 and —NHC(O)NR.sup.8R.sup.9, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.5 and R.sup.6 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.7, —C(O)R.sup.7, —C(O)OR.sup.7, —S(O).sub.mR.sup.7, —NR.sup.8R.sup.9 and —NHC(O)NR.sup.8R.sup.9, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.7 is selected from the group consisting of hydrogen, alkyl, amino, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.8 and R.sup.9 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; and m is 0, 1 or 2; and wherein the MOR agonist is a compound of formula (II): ##STR00044## or a tautomer, mesomer, racemate, enantiomer, diastereomer thereof, or mixture thereof, or a pharmaceutically acceptable salt thereof, wherein: ring A is selected from the group consisting of cycloalkyl and heterocyclyl; R is selected from the group consisting of aryl and heteroaryl, wherein the aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5; each R.sup.1 is identical or different and each is independently selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5, wherein the alkyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; each R.sup.2 is identical or different and each is independently selected from the group consisting of hydrogen, alkyl, alkoxy, haloalkyl, halogen, amino, nitro, hydroxy, cyano, oxo, alkenyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, —OR.sup.3, —C(O)R.sup.3, —C(O)OR.sup.3, —S(O).sub.mR.sup.3 and —NR.sup.4R.sup.5, wherein the alkyl, alkoxy, alkenyl, haloalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of deuterium, alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; or two R.sup.2 are taken together to form a cycloalkyl or heterocyclyl, wherein the cycloalkyl or heterocyclyl is optionally substituted by one or more substituents selected from the group consisting of alkyl, haloalkyl, halogen, amino, nitro, cyano, hydroxy, alkoxy, haloalkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.3 is selected from the group consisting of hydrogen, alkyl, deuterated alkyl, amino, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; R.sup.4 and R.sup.5 are each independently selected from the group consisting of hydrogen, alkyl, alkoxy, hydroxyalkyl, hydroxy, amino, alkoxycarbonyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein the alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl are each optionally substituted by one or more substituents selected from the group consisting of alkyl, halogen, hydroxy, amino, alkoxycarbonyl, nitro, cyano, alkoxy, hydroxyalkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl; p and q are each independently 0, 1, 2, 3 or 4; and m is 0, 1 or 2.

15. The method according to claim 4, wherein the KOR agonist is ##STR00045## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

16. The method according to claim 7, wherein the MOR agonist is ##STR00046## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

17. The method according to claim 10, wherein the malignant proliferative disease is selected from the group consisting of leukemia, lymphoma, myeloma, breast cancer, lung cancer, esophageal cancer, stomach cancer, colorectal cancer, liver cancer, pancreatic cancer, head and neck cancer, kidney cancer, bladder cancer, prostate cancer, ovarian cancer, endometrial cancer, cervical cancer, osteosarcoma, soft tissue sarcoma, melanoma and brain tumor.

18. A method of alleviating and/or treating pain in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a κ opioid receptor (KOR) agonist and a μ opioid receptor (MOR) agonist, wherein the KOR agonist is selected from the group consisting of: ##STR00047## ##STR00048## ##STR00049## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, and the MOR agonist is selected from the group consisting of: ##STR00050## ##STR00051## ##STR00052## ##STR00053## ##STR00054## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

19. The method according to claim 18, wherein the KOR agonist is ##STR00055## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, and the the MOR agonist is ##STR00056## or a tautomer, mesomer, racemate, enantiomer, or diastereomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof.

20. The method according to claim 18, wherein the pain is selected from the group consisting of acute pain and chronic pain, and the chronic pain is selected from the group consisting of headache, maxillofacial pain, cervical and occipital pain, neck and shoulder pain, upper limb pain, chest pain, abdominal pain, lumbocrural pain, genital tract pain, urinary tract pain and dysmenorrhea.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the effect of the combination of the KOR agonist and the MOR agonist (compound 5 and compound 20) of the present invention on the mechanical withdrawal threshold of rats in the incision pain test.

DETAILED DESCRIPTION OF THE INVENTION

(2) The exemplary experimental solutions for the use of the composition of the present invention in alleviating and/or treating pain are provided below in order to demonstrate the favorable activity and beneficial technical effects of the composition of the present invention. However, it should be understood that the following experimental solutions are merely examples of the present invention and are not intended to limit the scope of the present invention. A person skilled in the art, based on the teachings of the specification, can make suitable modifications or alterations to the technical solutions of the present invention without departing from the spirit and scope of the present invention.

Example 1. Preparation of Compound 5

(3) Compound 5 was identified by nuclear magnetic resonance (NMR) and/or mass spectrometry (MS). NMR shifts (δ) are given in 10.sup.−6 (ppm). NMR was determined by a Bruker AVANCE-400 machine. The solvents for determination were deuterated-dimethyl sulfoxide (DMSO-d.sub.6), deuterated-chloroform (CDCl.sub.3) and deuterated-methanol (CD.sub.3OD), and the internal standard was tetramethylsilane (TMS).

(4) MS was determined by a FINNIGAN LCQAd (ESI) mass spectrometer (manufacturer: Thermo, type: Finnigan LCQ advantage MAX).

(5) Yantai Huanghai HSGF254 or Qingdao GF254 silica gel plate was used as the thin-layer silica gel chromatography (TLC) plate. The dimension of the silica gel plate used in TLC was 0.15 mm to 0.2 mm, and the dimension of the silica gel plate used in product purification was 0.4 mm to 0.5 mm.

(6) Yantai Huanghai 200 to 300 mesh silica gel was generally used as a carrier for column chromatography.

(7) Prep Star SD-1 (Varian Instruments Inc.) or SFC-multigram (Berger Instruments Inc.) is used for chiral preparative column chromatography.

(8) The known starting materials of the present invention can be prepared by the known methods in the art, or can be purchased from ABCR GmbH & Co. KG, Acros Organnics, Aldrich Chemical Company, Accela ChemBio Inc., or Dari Chemical Company, etc.

(9) Unless otherwise stated, the solution refers to an aqueous solution.

(10) Unless otherwise stated, the reaction temperature is room temperature from 20° C. to 30° C.

(11) The reaction process in the examples was monitored by thin layer chromatography (TLC), and the developing solvent system used in the reactions included: A: dichloromethane and methanol system, B: n-hexane and ethyl acetate system, C: petroleum ether and ethyl acetate system, D: acetone. The volume ratio of the solvents was adjusted according to the polarity of the compounds. The eluent system in column chromatography and the developing solvent system in thin layer chromatography for purification of the compounds included: A: dichloromethane and methanol system, B: n-hexane and ethyl acetate system, C: dichloromethane and acetone system. The volume ratio of the solvents was adjusted according to the polarity of the compounds, and a small quantity of alkaline reagent such as triethylamine or acidic reagent such as acetic acid can also be added for adjustment.

(12) High pressure liquid chromatograph used in the high performance liquid chromatography in the examples was a Gilson-281, the chromatographic column was a Shim-pack PREP-ODS from Shimadzu, the mobile phase used was a trifluoroacetic acid buffer system, i.e., water (containing 0.05% trifluoroacetate)-acetonitrile.

(13) Each of the compounds in the form of a trifluoroacetate salt in the examples can be obtained in a free state by the following general method: the trifluoroacetate salt thereof was dissolved in a suitable solvent (such as methanol, ethanol, tetrahydrofuran, acetone, etc.), and a weak base was added (such as sodium bicarbonate, sodium carbonate, potassium carbonate, etc.) to adjust the pH to be neutral, the solution was concentrated under reduced pressure, and the residne was purified to obtain a free state

(14) ##STR00027##

4-Amino-1-((2R,5R,8R,14R)-2-(4-aminobutyl)-8-benzyl-5-isobutyl-4,7,10-trioxo-14-phenyl-3,6,9,12-tetraazapentadecan-1-oyl)piperidine-4-carboxylic acid

(15) ##STR00028## ##STR00029##

4-Benzyl 1-tert-butyl 4-(((benzyloxy)carbonyl)amino)piperidine-1,4-dicarboxylate 1b

(16) 4-(((Benzyloxy)carbonyl) amino)-1-(tert-butoxycarbonyl)piperidine-4-carboxylic acid 1a (1.2 g, 0.0032 mol, prepared by a known method disclosed in “Bioorganic Medicinal Chemistry Letters, 2007, 7(9), 2448-2451”), benzyl bromide (0.65 g, 0.0038 mol) and cesium carbonate (2.1 g, 0.0064 mol) were dissolved in 20 mL of N,N-dimethylformamide, and stirred for 12 hours at room temperature. The reaction solution was poured into water and extracted with ethyl acetate (30 mL×3). The organic phases were combined, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure, and the resulting residue was purified by thin layer chromatography with elution system B to obtain the title compound 1b (800 mg, a colorless viscous substance, yield: 53%).

Step 2

Benzyl 4-(((benzyloxy)carbonyl)amino)piperidine-4-carboxylate hydrochloride 1c

(17) Compound 1b (800 mg, 1.71 mmol) was dissolved in 2 mL of dichloromethane, and 2 mL of a solution of 4M hydrochloric acid in 1,4-dioxane was added. After stirring for 4 hours at room temperature, the reaction solution was concentrated under reduced pressure to obtain the crude title compound 1c (800 mg, a light yellow viscous substance), which was used directly in the next step without purification.

Step 3

(R)-Benzyl 1-(2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)hexanoyl)-4-(((benzyloxy)carbonyl)amino)piperidine-4-carboxylate 1e

(18) The crude compound 1c (800 mg, 1.97 mmol) and (R)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)hexanoic acid 1d (926 mg, 1.97 mmol, prepared by a known method disclosed in “ChemMedChem, 2015, 10(7), 1232-1239”) were dissolved in 20 mL of N,N-dimethylformamide. 2-(7-azabenzotriazol)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (1.12 g, 3.0 mmol) and N,N-diisopropylethylamine (0.7 mL, 3.94 mmol) were added. After stirring for 12 hours at room temperature, the reaction solution was poured into 2N citric acid solution and extracted with ethyl acetate (30 mL×3). The organic phases were combined, washed with saturated sodium bicarbonate solution, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to obtain the crude title compound 1e (1.6 g, a yellow viscous substance), which was used directly in the next step without purification.

Step 4

(R)-Benzyl 1-(2-amino-6-((tert-butoxycarbonyl)amino)hexanoyl)-4-(((benzyloxy) carbonyl)amino)piperidine-4-carboxylate 1f

(19) The crude compound 1e (1.6 g, 0.002 mol) was dissolved in 10 mL of dichloromethane, and then 10 mL of piperidine was added. After stirring for 2 hours at room temperature, the reaction solution was concentrated under reduced pressure. The resulting residue was purified by thin layer chromatography with elution system A to obtain the title compound 1f (900 mg, a light yellow solid, yield: 77%).

Step 5

(R)-Benzyl 2-((R)-2-(2-chloroacetamido)-3-phenylpropionamido)-4-methylpentanoate 1i

(20) (R)-Benzyl 2-((R)-2-amino-3-phenylpropanamido)-4-methylpentanoate 1g (500 mg, 1.36 mmol, prepared by a method disclosed in the patent application “US20110212882A1”) and triethylamine (275 mg, 2.72 mmol) were dissolved in 10 mL of dichloromethane, and then chloroacetyl chloride (230 mg, 2 mmol) was added dropwise. After stirring for 12 hours at room temperature, the reaction solution was poured into water and washed with saturated ammonium chloride solution. The organic phase was dried over anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure to obtain the crude title product 1i (500 mg, a yellow viscous substance), which was used directly in the next step without purification.

Step 6

(R)-Benzyl 4-methyl-2-((R)-3-phenyl-2-(2-(((R)-2-phenylpropyl)amino)acetamido)propanamido)pentanoate 5b

(21) Compound 1i (500 mg, 1.12 mmol) and (R)-2-phenylpropan-1-amine 5a (228 mg, 1.68 mmol, prepared by a known method disclosed in “Angewandte Chemie, International Edition, 2003, 42(39), 4793-4795”) were dissolved in 10 mL of N,N-dimethylformamide, and then potassium iodide (372 mg, 2.24 mmol) and potassium carbonate (309 mg, 2.24 mmol) were added. The reaction solution was warmed up to 60° C. and stirred for 12 hours. The reaction solution was cooled to room temperature, added with water, and extracted with dichloromethane (30 mL×3). The organic phases were combined, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to obtain the crude title compound 5b (600 mg, a brown viscous substance), which was used directly in the next step without purification.

Step 7

(9R,12R)-Benzyl 9-benzyl-12-isobutyl-2,2-dimethyl-4,7,10-trioxo-5-((R)-2-phenylpropyl)-3-oxa-5,8,11-triazatridecan-13-oate 5c

(22) The crude compound 5b (600 mg, 1.1 mmol) was dissolved in 20 mL of dichloromethane, and then di-tert-butyl dicarbonate (361 mg, 1.66 mmol) and triethylamine (222 mg, 2.2 mmol) were added. After stirring for 12 hours at room temperature, the reaction solution was concentrated under reduced pressure. The resulting residue was purified by thin layer chromatography with elution system A to obtain the title compound 5c (580 mg, a light yellow viscous substance, yield: 82%).

Step 8

(9R,12R)-9-benzyl-12-isobutyl-2,2-dimethyl-4,7,10-trioxo-5-((R)-2-phenylpropyl)-3-oxa-5,8,11-triazatridecan-13-oic acid 5d

(23) Compound 5c (580 mg, 0.9 mmol) was dissolved in 10 mL of methanol, and then palladium-carbon (60 mg, catalytic amount) was added. After completion of the addition, the reaction system was purged with hydrogen three times and stirred for 12 hours at room temperature. The reaction solution was filtered through celite, and the filtrate was concentrated under reduced pressure to obtain the crude title compound 5d (500 mg, a light yellow viscous substance), which was used directly in next step without purification.

Step 9

Benzyl 1-((9R,12R,15R)-9-benzyl-15-(4-((tert-butoxycarbonyl)amino)butyl)-12-isobutyl-2,2-dimethyl-4,7,10,13-tetraoxo-5-((R)-2-phenylpropyl)-3-oxa-5,8,11,14-tetraazahexadecan-16-oyl)-4-(((benzyloxy)carbonyl)amino)piperidine-4-carboxylate 5e

(24) The crude compound 5d (365 mg, 0.66 mmol), if (393 mg, 0.66 mmol), 2-(7-azabenzotriazol)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (376 mg, 0.99 mmol) and N,N-diisopropylethylamine (0.16 mL, 0.99 mmol) were dissolved in 10 mL of N,N-dimethylformamide. After stirring for 2 hours at room temperature, the reaction solution was concentrated under reduced pressure. The resulting residue was purified by thin layer chromatography with elution system A to obtain the title compound 5e (170 mg, a light yellow solid, yield: 23%).

Step 10

4-Amino-1-((9R,12R,15R)-9-benzyl-15-(4-((tert-butoxycarbonyl)amino)butyl)-12-isobutyl-2,2-dimethyl-4,7,10,13-tetraoxo-5-((R)-2-phenylpropyl)-3-oxa-5,8,11,14-tetraazahexadecan-16-oyl)piperidine-4-carboxylic acid 5f

(25) Compound 5e (80 mg, 0.0706 mmol) was dissolved in 10 mL of methanol, then palladium-carbon (10 mg, catalytic amount) was added. After completion of the addition, the reaction system was purged with hydrogen three times and stirred for 12 hours at room temperature. The reaction solution was filtered through celite, and the filtrate was concentrated under reduced pressure to obtain the crude title compound 5f (60 mg, a white solid), which was used directly in the next step without purification.

Step 11

4-Amino-1-((2R,5R,8R,14R)-2-(4-aminobutyl)-8-benzyl-5-isobutyl-4,7,10-trioxo-14-phenyl-3,6,9,12-tetraazapentadecan-1-oyl)piperidine-4-carboxylic acid trifluoroacetate 5g

(26) The crude product 5f (60 mg, 0.066 mmol) was dissolved in 2 mL of dichloromethane, and then 1 mL of a solution of 4M hydrochloric acid in 1,4-dioxane was added. After stirring for 2 hours at room temperature, the reaction solution was concentrated under reduced pressure. The resulting residue was purified by high performance liquid chromatography to obtain the title compound 5g (30 mg, a white solid).

(27) MS m/z (ESI): 708.6 [M+1]

Step 12

4-Amino-1-((2R,5R,8R,14R)-2-(4-aminobutyl)-8-benzyl-5-isobutyl-4,7,10-trioxo-14-phenyl-3,6,9,12-tetraazapentadecan-1-oyl)piperidine-4-carboxylic acid 5

(28) Compound 5g (30 mg, 0.028 mmol) was dissolved by 5 mL of a mixed solvent of methanol/water (V:V=10:1), and then sodium bicarbonate solid (10 mg) was added to adjust the pH to 7. The reaction solution was stirred for 30 minutes, and then was concentrated under reduced pressure. The resulting residue was added with 10 mL of dichloromethane, stirred for 30 minutes, and filtered. The filter cake was rinsed with 10 mL of dichloromethane, and the filtrate was concentrated under reduced pressure to obtain the title compound 5 (17 mg, a white solid).

(29) MS m/z (ESI): 708.6 [M+1]

(30) .sup.1H NMR (400 MHz, CD.sub.3OD): δ 7.33-7.19 (m, 10H), 4.90-4.84 (m, 2H), 4.64-4.61 (m, 2H), 4.42-4.39 (m, 1H), 3.86-3.74 (m, 5H), 3.20-3.12 (m, 4H), 2.94-2.84 (m, 4H), 2.61-2.54 (m, 2H), 2.20-2.15 (m, 3H), 1.79-1.70 (m, 2H), 1.68-1.60 (m, 8H), 1.45-1.40 (m, 3H), 1.30-1.20 (m, 5H), 0.99-0.76 (m, 6H).

Example 2. Preparation of Compound 20

(31) The apparatus, equipment and materials required for the preparation of compound 20 are shown in Example 1.

(32) ##STR00030##

(1S,4S)-4-Ethoxy-N-(2-((R)-9-(pyridin-2-yl)-6-oxaspiro[4.5]decan-9-yl)ethyl)-1,2,3,4-tetrahydronaphthalen-1-amine

(33) ##STR00031##

(S)-Tert-butyl (1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 11a

(34) (S)-1,2,3,4-Tetrahydronaphthalen-1-amine 10a (3 g, 20.41 mmol, prepared according to the known method disclosed in “Angewandte Chemie-International Edition, 45(28), 4641-4644, 2006”) was dissolved in 100 mL of dichloromethane, and then triethylamine (5.7 mL, 40.82 mmol) and di-tert-butyl dicarbonate (4.9 g, 22.45 mmol) were added. After stirring for 12 hours, the reaction solution was washed successively with water (100 mL) and saturated sodium bicarbonate solution (100 mL). The organic phase was dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to obtain the crude title product 11a (5.6 g) as a light yellow oil, which was used directly in the next step without purification.

(35) MS m/z (ESI): 248.3 [M+1]

Step 2

(S)-Tert-butyl (4-oxo-1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 11b

(36) The crude (S)-tert-butyl (1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 11a (5.6 g, 20.41 mmol) was dissolved in 90 mL of a mixed solution of acetone and water (V/V=2:1), and then magnesium sulfate (5.5 g, 45.66 mmol) was added and potassium permanganate (7.22 g, 45.66 mmol) was slowly added with stirring. The reaction system was stirred for 12 hours. Then, the reaction solution was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromtography with n-hexane/ethyl acetate system to obtain the title product 11b (3.1 g, yield 52%) as an off-white solid.

(37) MS m/z (ESI): 262.3 [M+1]

Step 3

Tert-butyl ((1S,4S)-4-hydroxy-1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 14a

(38) (S)-Tert-butyl (4-oxo-1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 11b (100 mg, 0.883 mmol) was dissolved in 5 mL of toluene. The reaction solution was cooled to 0° C., added with (R)-2-methyl-CBS-oxazaborolidine (0.1 ml, 0.076 mmol), and stirred for 5 minutes. Then, borane methylsulfide (0.88 ml, 0.76 mmol) was added, and the reaction was stirred for 2 hours. The reaction was quenched by adding 50 ml of saturated sodium chloride solution, and extracted with ethyl acetate (30 mL×3). The organic phases were combined, washed with saturated sodium chloride solution (30 mL×3), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure, and the resulting residue was purified by thin layer chromtography with dichloromethane/methanol system to obtain the title product 14a (60 mg, yield 60%) as a white solid.

(39) MS m/z (ESI): 208.3 [M−55]

Step 2

Tert-butyl ((1S,4S)-4-ethoxy-1,2,3,4-tetrahydronaphthalen-1-yl)carbamate 19a

(40) The crude tert-butyl ((1S)-4-hydroxy-1,2,3,4-tetrahydronaphthalen-1-yl) carbamate 14a (850 mg, 3.23 mmol), silver oxide (76 mg, 0.33 mmol) and iodoethane (1.3 mL, 16.15 mmol) were dissolved in 30 mL of dichloromethane, and the reaction solution was stirred for 48 hours. The reaction solution was filtered, and the filtrate was concentrated under reduced pressure to obtain the crude title product 19a (800 mg) as a yellow oil, which was used directly in the next step without purification.

(41) MS m/z (ESI): 236.1 [M−55]

Step 3

(1S,4S)-4-Ethoxy-1,2,3,4-tetrahydronaphthalen-1-amine 19b

(42) The crude compound 19a (698 mg, 2.4 mmol) was dissolved in 4 mL of dichloromethane, and then 8 mL of a solution of 4 M hydrogen chloride in 1,4-dioxane were added. After stirring for 2 hours, the reaction solution was concentrated under reduced pressure, triturated with ethyl acetate (30 mL) and filtered. The filter cake was dissolved in 20 mL of a mixed solution of dichoromethane and methanol (V:V=5:1). Saturated sodium bicarbonate solution was added to adjust the pH of the reaction solution to 7 to 8. The reaction solution was concentrated under reduced pressure, washed with a mixed solution of dichloromethane and methanol (V:V=5:1) (30 mL×2) and filtered. The filtrate was concentrated under reduced pressure to obtain the crude title product 19b (310 mg) as a yellow liquid, which was used directly in next step without purification.

(43) MS m/z (ESI): 191.1 [M+1]

Step 4

(1S,4S)-4-Ethoxy-N-(2-((R)-9-(pyridin-2-yl)-6-oxaspiro[4.5]decan-9-yl)ethyl)-1,2,3,4-tetrahydronaphthalen-1-amine 20

(44) (R)-2-(9-(Pyridin-2-yl)-6-oxaspiro[4.5]decan-9-yl)acetaldehyde 5a (500 mg, 1.85 mmol, prepared according to the method disclosed in the patent application “WO2012129495”) and the crude compound 19b (310 mg, 1.85 mmol) were dissolved in 30 mL of dichloromethane, and the mixture was stirred for 40 minutes, and then sodium triacetoxyborohydribe (980 mg, 4.63 mmol) was added. After stirring for 2 hours, the reaction solution was washed successively with saturated sodium bicarbonate solution (30 mL×3) and saturated sodium chloride solution (30 mL×3). The organic phase was dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure, and the resulting residue was purified by thin layer chromatography with dichloromethane/methanol system to obtain the title product 20 (280 mg, yield 35%) as a yellow viscous solid.

(45) MS m/z (ESI): 435.3 [M+1]

(46) .sup.1H NMR (400 MHz, CDCl.sub.3) δ 9.74 (d, 1H), 9.58 (d, 1H), 8.94 (d, 1H), 8.37 (d, 1H), 7.94 (d, 1H), 7.67 (d, 1H), 7.52 (d, 1H), 7.47 (t, 1H), 4.46-4.49 (m, 1H), 4.30-4.33 (m, 1H), 3.84-3.87 (m, 1H), 3.66-3.70 (m, 2H), 3.53-3.56 (m, 2H), 2.82-2.85 (d, 2H), 2.67 (s, 2H), 2.39-2.41 (m, 4H), 2.30-2.33 (m, 4H), 1.85 (s, 2H), 1.48-1.52 (m, 6H), 1.27 (m, 3H).

Example 3. Treatment Effect of the Combination of the KOR Agonist and the MOR Agonist of the Present Invention on Incision Pain in Rats

Test Compounds

(47) Compound 5 (prepared according to the method described in Example 1), and compound 20 (prepared according to the method described in Example 2). The compound dose was calculated on bases.

(48) Test Animals

(49) Experimental male Wistar rats were purchased from Shanghai Slac Laboratory Animal Co., Ltd. The rats weighed 140-160 g when purchased, and were fed at 5 rats/cage, under a condition of 12/12 hours light/dark cycle adjustment, a constant temperature of 23±1° C., a humidity of 50-60%, and free access to food and water. After purchase, the animals were subjected to an adaptive feeding for more than 3 days before the experiment was started.

Experimental Apparatus

(50) Electronic Von Frey: UGO BASILE, type 38450.

Formulation of the Solution of the Test Compound

(51) Both compound 5 and compound 20 were formulated with normal saline.

Test Method

(52) The rats were randomly divided into the following groups according to the body weight: blank control group (n=10), model group (n=10) and drug-administered group (n=50). The drug-administered group was divided into the following groups: compound 20-0.03 mg/kg group (n=10), compound 5-0.3 mg/kg group (n=10), compound 5-0.1 mg/kg+compound 20-0.03 mg/kg group (n=10), compound 5-0.3 mg/kg+compound 20-0.03 mg/kg group (n=10), and compound 5-1 mg/kg+compound 20-0.03 mg/kg group (n=10). The model group and drug-administered group were subjected to an incision surgery. During the surgery, the rats were anesthetized with isoflurane. An incision (1 cm long) passing through the skin and fascia was made with a No. 10 surgical blade in the middle of the left hind paw. The skin was sutured with a 3-0 sterile silk surgical suture. The injured site was disinfected with antibiotic ointment and iodophor. The animals were returned to their original place to recover overnight. After 24 hours, the drug was injected through the tail vein, and the blank control group and the model group were administrated with normal saline two times with an interval of 15 minutes. The group administered with compound 20 alone was intravenously injected with the corresponding dose of compound 20 and the blank solvent for formulating compound 5. The group administered with compound 5 alone was intravenously injected with the corresponding dose of compound 5 and the blank solvent for formulating compound 20. The group administered with the combination was intravenously injected with the corresponding dose of compound 5, and then intravenously injected with the corresponding dose of compound 20 after 15 minutes. The mechanical pain threshold of each group was measured by the Electronic Von Frey 30 minutes after the injection to evaluate the analgesic effect of the drug on the surgical incision pain and the intensity thereof.

Data Representation and Statistical Processing

(53) The experimental data were expressed as mean±standard deviation (S.D.). Statistical comparisons were performed using t test in the Excel software. The data between the model group and the blank control group were analyzed and compared to determine whether there was a significant statistical difference or not. #P<0.05 indicates that there is a significant difference between the model group and the blank control group, and ##P<0.01 indicates that there is a highly significant difference between the model group and the blank control group. ΔP<0.05 indicates that there is a significant difference between the drug-administered group and the model group, and ΔΔP<0.01 indicates that there is a highly significant difference between the drug-administered group and the model group. *P<0.05 indicates that there is a significant difference between the drug-combination-administered group and the single-drug-administered group, and **P<0.01 indicates that there is a highly significant difference between the drug-combination-administered group and the single-drug-administered group.

Experimental Results

(54) The results are shown in FIG. 1.

Experimental Conclusion

(55) The experimental results (FIG. 1, mpk is the abbreviation of mg/kg) showed that the tenderness threshold of the blank control group of the rats was 14.48 g, and the tenderness threshold of the model group was 8.91 g. Compared with the blank control group, the tenderness threshold of the model group was significantly decreased (P<0.05). After the drug administration, compared with the model group, the tenderness threshold of the compound 20-0.03 mg/kg group was significantly increased (P<0.01) to 14.46 g, with an increase of 62.3%; the tenderness threshold of the compound 5-0.3 mg/kg group was significantly increased (P<0.01) to 17.92 g, with an increase of 101.1%.

(56) Compared with the model group, the combination of compound 20-0.03 mg/kg and compound 5-0.1 mg/kg, compound 5-0.3 mg/kg or compound 5-1 mg/kg all can significantly increase (P<0.01) the tenderness threshold of rats to 17.96 g, 22.29 g or 33.46 g, with an increase of 101.6%, 150.1% or 275.5%, respectively, indicating the dose-effect relationship of KOR agonist. The combined effects with three doses were better than the effect of compound 20-0.03 mg/kg alone. The combination of compound 20-0.03 mg/kg and compound 5-0.3 mg/kg or compound 5-1 mg/kg had a statistical difference (P<0.01).

(57) Compared with compound 5-0.3 mg/kg alone, the combination of compound 20-0.03 mg/kg+compound 5-0.1 mg/kg had an equivalent increase of tenderness threshold. The combined effects of compound 20-0.03 mg/kg and compound 5-0.3 mg/kg or compound 5-1 mg/kg were better than the effect of compound 5-0.3 mg/kg alone. The combination of compound 20-0.03 mg/kg and compound 5-1 mg/kg had a statistical difference (P<0.01).

(58) In summary, the administration of compound 20-0.03 mg/kg alone or compound 5-0.3 mg/kg alone to the rat had a good effect of decreasing incision pain (P<0.01). In addition, the test results of the combined administration group showed that compound 20 and compound 5 had a synergistic effect, and the effect of the combination of compound 20 and compound 5 was better than that of the compound administered alone at the same dose.