Liquid triblock copolymer

Abstract

A bioresorbable triblock copolymer according to Formula 1
R-B-A-B-R(1)
wherein A is a hydrophilic polymer, B a hydrophobic polymer and R are end-groups, wherein R is H or a C1-C30 organic moiety and wherein the copolymer is fluid in a temperature range of 0 C. to 37 C. A pharmaceutical composition including the triblock copolymer and at least one therapeutically active agent. The copolymer and pharmaceutical composition can be used for forming a depot in a human or animal body or as medical device.

Claims

1. A bioresorbable triblock copolymer according to Formula 1
R-B-A-B-R(1) wherein A is a hydrophilic polymer, B a hydrophobic polymer and R are end-groups, wherein R is a C1-C30 organic moiety, wherein A is polyethyleneglycol (PEG) having a molecular weight between 180 and 700 g/mol, wherein a number average molecular weight (Mn) of the triblock copolymer is within the range of 700-2500 g/moL, and wherein the copolymer is fluid in a temperature range of 0 C. to 37 C.

2. The copolymer according to claim 1, wherein the copolymer has a viscosity determined at 20 C. having a value below 30 Pa.Math.s, as determined by shear rheology.

3. The copolymer according to claim 1, wherein the copolymer has a Tg (midpoint) below 20 C.

4. The copolymer according to claim 1, wherein the copolymer has a Tm (midpoint) below 20 C.

5. The copolymer according to claim 1, wherein each B block is a combination of -caprolactone with anyone of lactide, glycolide, -valerolactone, p-dioxanone or trimethylenecarbonate; or a combination of -valerolactone with anyone of lactide, glycolide, p-dioxanone or trimethylenecarbonate; or a combination of p-dioxanone with lactide, glycolide or trimethylenecarbonate; or a combination of trimethylenecarbonate with lactide or glycolide.

6. The copolymer according to claim 1, wherein R is chosen from fatty acid residues, ether residue or urethane residue.

7. The copolymer according to claim 1, wherein R is chosen from an acetyl group, a propionyl group, a hexanoyl group, a nonanoyl group, a dodecanoyl group, pentadecanoyl group, a stearoyl group or a benzoyl group, and wherein R is linear, branched or cyclic and R can be optionally substituted with heteroatoms.

8. The copolymer according to claim 1, wherein the copolymer has a viscosity determined at 20 C. having a value below 20 Pa.Math.s as determined by shear rheology, wherein the copolymer has a Tg (midpoint) below 30 C., wherein the copolymer has a Tm (midpoint) below 10 C., and wherein the copolymer has a number average molecular weight (Mn) between 600 and 3,000 g/mol.

9. The copolymer according to claim 8, wherein the copolymer has a viscosity determined at 20 C. having a value below 10 Pa.Math.s as determined by shear rheology, wherein the copolymer has a Tg (midpoint) below 40 C., wherein the copolymer has a Tm (midpoint) below 0 C., and wherein the copolymer has a number average molecular weight (Mn) between 700 and 2500 g/mol.

10. The copolymer according to claim 9, wherein each B block is a combination of -caprolactone with anyone of lactide, glycolide, -valerolactone, p-dioxanone or trimethylenecarbonate; or a combination of -valerolactone with anyone of lactide, glycolide, p-dioxanone or trimethylenecarbonate; or a combination of p-dioxanone with lactide, glycolide or trimethylenecarbonate; or a combination of trimethylenecarbonate with lactide or glycolide, and wherein R is chosen from fatty acid residues, ether residue or urethane residue.

11. A process for preparing a pharmaceutical composition, comprising the steps of providing the triblock copolymer according to claim 1, providing at least one therapeutically active agent and mixing the copolymer with the therapeutically active agent.

12. A pharmaceutical composition comprising one or more triblock copolymers according to claim 1, and at least one therapeutically active agent.

13. The pharmaceutical composition according to claim 12, wherein the composition comprises at least 50 wt % of the triblock copolymers, relative to the total weight of the pharmaceutical composition.

14. The pharmaceutical composition according to claim 12, wherein the composition has a dynamic viscosity below or equal to 30 Pa.Math.s at 20 C., as determined by shear rheology.

15. The pharmaceutical composition according to claim 14, wherein the composition has a dynamic viscosity below 20 Pa.Math.s as determined by shear rheology.

16. The pharmaceutical composition according to claim 14, wherein the composition has a dynamic viscosity below 5 Pa.Math.s as determined by shear rheology.

17. A pharmaceutical composition comprising one or more triblock copolymers according to claim 9, and at least one therapeutically active agent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the injectability setup for measuring the ejection time of a block copolymer by means of a syringe.

(2) FIG. 2 shows the viscosity of various PEG200 derivatives at 20 C. and 37 C. versus the T.sub.g ( C.).

(3) FIG. 3 shows the viscosity of various PEG600 derivatives at 20 C. and 37 C. versus the T.sub.g ( C.).

(4) FIG. 4 shows the cumulative release (%) of lidocaine-HCl versus the release time (days) for the release of lidocaine-HCl from PEG200(cap50-lac50)5.0.

(5) FIG. 5 shows the cumulative release (%) of lidocaine-HCl versus the release time (days) for the release of lidocaine-HCl from PEG200(cap75-lac25)5.0.

(6) FIG. 6 shows the cumulative release (%) of lidocaine-HCl versus the release time (days) for the release of lidocaine-HCl from three different PEG200 block copolymers with a C6 end-group.

(7) FIG. 7 shows the cumulative release (%) of lidocaine-HCl versus the release time (days) for the release of lidocaine-HCl from PEG600(cap50-lac50)1.0.

(8) FIG. 8 shows the cumulative release (%) of lysozyme versus the release time (days) for the release of lysozyme from PEG200(cap50-lac50)5.0.

(9) FIG. 9 shows the cumulative release (%) of lysozyme versus the release time (days) for the release of lysozyme from three different PEG200 block copolymers.

(10) FIG. 10 shows the cumulative release (%) of lysozyme versus the release time (days) for the release of lysozyme from three different PEG200 block copolymers with a C3 end-group.

(11) FIG. 11 is another example of what the effect is of an end-group on the in vitro release results using the PEG200(cap50-TMC50) 5.0 matrix. Slight differences were observed after 24 hours. After 7 days the effect of the end-group could be seen. After 7 days the copolymer with R=H showed a lidocaine-HCl release of approx. 24%. The C3-endcapped showed a release of approx. 11%, a greater effect had the branched end-group with a release of approx. 2% after 7 days.

(12) FIG. 12 shows the effect of an end-group on the in vitro release results using the PEG200(cap.sub.50-diox.sub.50).sub.5.0 matrix. Big differences were observed after 24 hours. The non-endcapped copolymer showed a lidocaine-HCl release of approx. 40% in 24 hours. Whereas the endcapped copolymers showed releases between the 0% and 6%. Even after 7 days almost no lidocaine-HCl was release from the copolymers with big endgroups (R=C6, C12 or 2-n-HD).

DETAILED DESCRIPTION OF THE INVENTION

(13) Materials:

(14) Toluene and n-pentane were purchased from Boom (Meppel, The Netherlands). -Caprolactone, triethylamine and propionic anhydride were purchased from Across Organics (New Jersey, USA) and PEG200, PEG600, PEG1000, hexanoic anhydride and tin(II)2-ethylhexanoate from Sigma Aldrich (St. Louis, USA). Lauric anhydride was purchased from ABCR (Karlsruhe, Germany). The API's lidocaine, lidocaine-HCl and lysozyme were purchased from Sigma Aldrich (St. Louis, USA), Celecoxib was purchased from LC Laboratories (Woburn, USA). The monomers L-lactide, D-lactide and glycolide were purchased from Purac (Gorinchem, The Netherlands).

(15) Test Methods

(16) Molecular weights were determined by GPC using an Agilent system Series 100 equipped with a guard column (PLgel 55 m, 7.550 mm) and three Varian columns (PLgel, 5 m, 500 , 3007.5 mm). Detection was performed with a refractive index detector. PEG standards of different molecular weights were used for reference. The eluent was THF, the elution rate was 1.0 ml/min. The column temperature was 35 C. The concentration of the samples was approx. 4 mg/ml in THF and the injection volume was 50 l. M.sub.n polymer is the number average molecular weight of the polymer relative to the PEG standards and measured in THF.

(17) Thermal properties of the polymers were determined by DSC (TA Instruments DSC Q2000 apparatus). Samples of approximately 10 mg in closed Aluminium pans were cooled from room temperature to 90 C. and kept isothermal for 5 minutes, after which they were heated to 70 C. with a heating rate of 10 C./min (modulated +/1 C. every 60 seconds). Next, the samples were cooled to 90 C. with a cooling rate of 5 C./min (modulated +/1 C. every 60 seconds), followed by a second heating cycle to 70 C. with a heating rate of 2 C./min (modulated +/1 C. every 60 seconds). Using the second heating run, the glass transition temperature (T.sub.g) was determined as the midpoint of heat capacity change and the melting temperature T.sub.m as the maximum temperature of the endothermic area.

(18) The injectability of each polymer was determined, by measuring how much time (seconds) was needed to eject a known volume through a needle (metal). In order to measure each sample using the same conditions a set-up was prepared as shown in FIG. 1.

(19) The polymer was charged in a plastic syringe 3 (1 ml) with a luer lock and fitted with a needle 4. Standard metal needles were used: 21 G 0.8050 mm, 25 G 0.5025 mm or 27 G 0.4020 mm. The syringe was locked in a clamp (not shown) and a weight 1 of 3,250 g was placed on the plunger 2. The plunger/weight interface was 0.8 cm.sup.2 creating a pressure of 4.06 kg/cm.sup.2 For the 21 G, 25 G and 27 G needle the time was measured how long it takes to eject 0.1 ml. Before ejection the syringes with polymer were stored for 2 days at 20 C. The measurements were performed at 20 C. The weight put on the plunger was chosen such that the measurement mimics manual injection.

(20) Viscosity measurements were carried out on a TA Instruments AR2000Ex with a plate-cone setup, type 40 mm cone, angle 1:00:00 deg:min:sec. During the viscosity measurement, the temperature was kept constant at either 20 C. or 37 C., with a shear rate 5 s.sup.1 during 300 s. Average viscosity values were calculated using software (Trios software, TA Instruments). In this way the average dynamic (shear) viscosity of the polymer is determined. Results are listed in Table 2 A and B.

(21) General Synthesis Procedure:

(22) In a three-neck round-bottom flask (500 ml) equipped with a Dean Stark trap and a condenser, PEG200 (20.6 g; 103 mmol), L-lactide (51.7 g; 359 mmol), -caprolactone (51.5 g; 452 mmol) and 250 ml toluene were introduced and, while stirring, heated to reflux under nitrogen atmosphere. The solution was azeotropically dried by distilling off 110 ml toluene/water. Next, it was cooled down to 90 C. and tin octoate (0.74 g; 1.8 mmol) was added. Ring-opening polymerization was carried out by refluxing the mixture overnight under nitrogen atmosphere. Subsequently, the solution was cooled down to room temperature.

(23) Synthesis 2-n-Hexyldecanoyl Chloride

(24) At ambient temperature, thionylchloride (60 ml, 826 mmol) was added drop wise to a solution of 2-n-hexyldecanoic acid (50 g, 195 mmol) in DCM (200 ml). The obtained mixture was stirred overnight at ambient temperature.

(25) Volatiles were evaporated under reduced pressure at 60 C. Finally the remaining material was stripped (3) with toluene (100 ml) at 60 C.

(26) Modification Procedures:

(27) Modification with Propionyl End-Group; PEG200(cap.sub.50-lac.sub.50).sub.5.0-C3

(28) To the reaction mixture, Et.sub.3N (52.5 g; 515 mmol; 5 eq.) and propionic anhydride (40 g, 310 mmol, 3 eq.) were added. The resulting mixture was refluxed, while stirring, for 1 hour.

(29) Modification with hexanoyl end-group; PEG200(cap.sub.50-lac.sub.50).sub.5.0-C6

(30) As described as with the modification with propionic anhydride. Propionic anhydride was replaced by hexanoic anhydride (66.3 g, 310 mmol. 3 eq.).

(31) Modification with dodecanoyl end-group; PEG200(cap.sub.50-lac.sub.50).sub.5.0-C12

(32) As described as with the modification with propionic anhydride. Propionic anhydride was replaced by lauric anhydride (125 g, 310 mmol. 3 eq.).

(33) Modification with 2-n-hexyldecanoyl end-group; PEG200(cap.sub.50-lac.sub.50).sub.5.0-2-n-HD

(34) Volatiles of the polymer solution were evaporated under reduced pressure at 60 C. The remaining crude polymer was dissolved in DCM (300 ml), followed by the addition of Et.sub.3N (52.5 g; 515 mmol; 5 eq.) and 2-n-hexyldecanoyl chloride (30.6 g, 257 mmol, 2.5 eq.) The resulting mixture was stirred for 2 hours at ambient temperature, after which the DCM was evaporated under reduced pressure at 60 C. EtOAc (100 ml) was added and the mixture was stirred for 10 minutes at ambient temperature. The formed solids were filtered off and the filtrate was diluted with DCM (200 ml). The obtained solution was poured into n-pentane (600 ml) containing separation funnel. After shaking, the polymer was allowed to settle to the bottom of the separation funnel. Polymer was collected and dried under reduced pressure at 60 C. and finally dried under high vacuum (<1 mBar) at 60 C. for at least 24 hrs.

(35) General Work-Up Procedure:

(36) The reaction mixture was poured into a separation funnel containing n-pentane (600 ml). After shaking the mixture, the polymer settled to the bottom of the funnel and could be collected. The obtained polymer was dried under reduced pressure for 2 hours at 60 C., followed by further drying in the vacuum oven (<0.2 mBar) at 90 C. for at least 24 hours.

(37) Using this method as described above a library of polymers was prepared. Variations were made by using different PEG blocks, changing type of monomers used in the B-block and length of B block, and varying the endgroups. Results are listed in table 1.

(38) Nomenclature.

(39) In the experimental section abbreviations of triblock copolymers have been used.

(40) For example PEG200(cap.sub.50-lac.sub.50).sub.5.0 means a triblock copolymer having an A-block made of PEG, having a molecular weight of 200 Da, and on each side of the A-block a B-block, wherein the total weight of the two B-blocks is equal to 5 times the weight of the A-block, and wherein each B-block comprises -caprolacton and lactide in a 50/50 (weight) ratio. In this case the RBABR triblock copolymer comprises on average an A block consisting of PEG having Mn 200, and two B blocks, each having a Mn of approximately 500 Da and containing 50 wt % -caprolacton and 50 wt % lactide. The end-group R is H in this case.

(41) In cases where R is not H, the carbon chain length has been added to the formula.

(42) For example PEG600(cap.sub.50-lac.sub.50).sub.2.0-06 indicates a RBABR triblock copolymer having an A-block consisting of PEG having a molecular weight (Mn) of 600, and two B-blocks each having a molecular weight (Mn) of approximately 600 (1200/2) and on each side a C6 R-group.

(43) Experiment 1; Preparation of Copolymers.

(44) A large number of RBABR copolymers have been prepared in accordance with the general synthesis procedure. Thermal properties and molecular weights have been determined. The results are listed in Table 1A and 1B.

(45) TABLE-US-00001 TABLE 1A Polymer synthesis Degree of Thermal properties # Polymer composition M.sub.n, PCLA PCLA/PEG CL/LA modifycation M.sub.n, polymer PDI T.sub.g ( C.) T.sub.m ( C.) 1 PEG200(cap.sub.50-lac.sub.50).sub.5.0 1000 5.0 1 1337 1.27 45 2 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C3 1000 5.0 1 2 1453 1.23 45 3 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C6 1000 5.0 1 2 1518 1.23 51 4 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C12 1000 5.0 1 2 1570 1.23 53 5 PEG200(cap.sub.50-lac.sub.50).sub.7.5 1500 7.5 1 1840 1.33 40 6 PEG200(cap.sub.50-lac.sub.50).sub.7.5-C3 1500 7.5 1 2 1850 1.38 39 7 PEG200(cap.sub.50-lac.sub.50).sub.7.5-C6 1500 7.5 1 2 1972 1.36 47 8 PEG200(cap.sub.50-lac.sub.50).sub.10 2000 10 1 2659 1.37 37 9 PEG200(cap.sub.50-lac.sub.50).sub.10-C3 2000 10 1 2 2275 1.50 36 10 PEG200(cap.sub.50-lac.sub.50).sub.10-C6 2000 10 1 2 2493 1.44 40 11 PEG600(cap.sub.50-lac.sub.50).sub.1.0 600 1.0 1 1206 1.10 57 5 12 PEG600(cap.sub.50-lac.sub.50).sub.1.0-C3 600 1.0 1 2 1255 1.10 58 5 13 PEG600(cap.sub.50-lac.sub.50).sub.1.0-C6 600 1.0 1 2 1387 1.09 63 8 14 PEG600(cap.sub.50-lac.sub.50).sub.2.0 1200 2.0 1 1767 1.20 51 15 PEG600(cap.sub.50-lac.sub.50).sub.2.0-C3 1200 2.0 1 2 1850 1.20 51 16 PEG600(cap.sub.50-lac.sub.50).sub.2.0-C6 1200 2.0 1 2 1989 1.20 55 17 PEG600(cap.sub.50-lac.sub.50).sub.4.0 2400 4.0 1 3254 1.32 40 18 PEG600(cap.sub.50-lac.sub.50).sub.4.0-C3 2400 4.0 1 2 3432 1.31 40 19 PEG600(cap.sub.50-lac.sub.50).sub.4.0-C6 2400 4.0 1 2 3182 1.36 45 20 PEG1000(cap.sub.50-lac.sub.50).sub.0.5 500 0.5 1 1520 1.06 48 25 21 PEG1000(cap.sub.50-lac.sub.50).sub.0.5-C3 500 0.5 1 2 1556 1.06 53 22 22 PEG1000(cap.sub.50-lac.sub.50).sub.0.5-C6 500 0.5 1 2 1661 1.04 62 15 23 PEG200(cap.sub.75-lac.sub.25).sub.5.0 1000 5.0 3 1422 1.26 62 1 24 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C3 1000 5.0 3 2 1487 1.27 61 1 25 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C6 1000 5.0 3 2 1688 1.24 66 8 26 PEG200(cap.sub.25-lac.sub.75).sub.5.0 1000 5.0 0.33 1277 1.24 27 27 PEG200(cap.sub.25-lac.sub.75).sub.5.0-C3 1000 5.0 0.33 2 1391 1.23 25 28 PEG200(cap.sub.25-lac.sub.75).sub.5.0-C6 1000 5.0 0.33 2 1514 1.20 30 29 PEG200(cap.sub.75-lac.sub.25).sub.7.5-C3 1500 7.5 3 2 1847 1.40 N.A. N.A. 30 PEG200(cap.sub.75-lac.sub.25).sub.7.5-C6 1500 7.5 3 2 2081 1.34 N.A. N.A.

(46) TABLE-US-00002 TABLE 2B Polymer synthesis Degree of Thermal properties # Polymer composition M.sub.n, PCLA PE/PEG m/m modification M.sub.n, polymer PDI Tg ( C.) Tm ( C.) 31 PEG200(cap.sub.75-lac.sub.25).sub.3.0-2-n-HD 600 3.0 3 2 1333 1.13 60 32 PEG200(cap.sub.50-lac.sub.50).sub.5.0-2-n-HD 1000 5.0 1 2 1566 1.17 60 33 PEG400(cap.sub.60-lac.sub.40).sub.5.0-succinic 1000 5.0 1.5 2 2493 1.41 38 34 PEG200(cap.sub.40-gly.sub.30-lac.sub.30).sub.5.0-2-n-HD 1000 5.0 2 1707 1.16 42 35 PEG200(cap.sub.50-gly.sub.50).sub.5.0-2-n-HD 1000 5.0 1 2 1776 1.15 50 36 PEG200(diox50-TMC50)5.0-2-n-HD 1000 5.0 1 2 1844 1.20 50 37 PEG200(cap.sub.50-TMC.sub.50).sub.5.0 1000 5.0 1 0 1676 1.55 59 38 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C3 1000 5.0 1 2 1764 1.51 59 39 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C6 1000 5.0 1 2 1910 1.47 62 40 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C12 1000 5.0 1 2 2365 1.36 74 30 41 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-2-n-HD 1000 5.0 1 2 1962 1.43 73 42 PEG200(cap.sub.50-val.sub.50).sub.5.0 1000 5.0 1 0 1269 1.19 45 5 43 PEG200(cap.sub.50-val.sub.50).sub.5.0-C3 1000 5.0 1 2 1670 1.27 N.A. N.A. 44 PEG200(cap.sub.50-val.sub.50).sub.5.0-C6 1000 5.0 1 2 1727 1.20 74 3 45 PEG200(cap.sub.50-val.sub.50).sub.5.0-C12 1000 5.0 1 2 2223 1.28 74 2 46 PEG200(cap.sub.50-val.sub.50).sub.5.0-2-n-HD 1000 5.0 1 2 2028 1.25 74 1 47 PEG200(cap.sub.75-val.sub.25).sub.5.0-C3 1000 5.0 3 2 1690 1.26 74 11 48 PEG200(cap.sub.75-val.sub.25).sub.5.0-C6 1000 5.0 3 2 1985 1.24 62 12 49 PEG200(cap.sub.75-val.sub.25).sub.5.0-C12 1000 5.0 3 2 2467 1.22 23 50 PEG200(cap.sub.75-lac.sub.25).sub.5.0-2-n-HD 1000 5.0 3 2 2197 1.11 63 51 PEG200(cap.sub.25-val.sub.75).sub.5.0-C3 1000 5.0 1/3 2 1600 1.23 73 15 52 PEG200(cap.sub.25-val.sub.75).sub.5.0-C6 1000 5.0 1/3 2 1707 1.24 75 14 53 PEG200(cap.sub.50-diox.sub.50).sub.5.0 1000 5.0 1 0 1300 1.22 60 54 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C2 1000 5.0 1 2 1273 1.23 58 55 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C6 1000 5.0 1 2 1245 1.17 73 4 56 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C12 1000 5.0 1 2 1529 1.16 74 17 57 PEG200(cap.sub.50-diox.sub.50).sub.5.0-2-n-HD 1000 5.0 1 2 1608 1.17 73

(47) In Table 1A and B PEG200, PEG600 and PEG1000 are polyethyleneglycol polymers with a molecular weight of respectively 200 g/mol, 600 g/mol and 1,000 g/mol.

(48) M.sub.n, PCLA is the molecular weight of both B-blocks together, as calculated based on the molecular weight of the PEG A-block.

(49) Cap is an abbreviation for -caprolactone.

(50) Lac is an abbreviation for L-lactide, D-Lactide or DL-Lactide If not specifically mentioned, L-Lactide is chosen by default.

(51) Gly is an abbreviation of glycolide

(52) Diox is an abbreviation of p-dioxanone

(53) TMC is an abbreviation of trimethylenecarbonate

(54) Val is an abbreviation of -valerolactone

(55) C3, C6 and C12 mean that the R-group comprises 3 (propionyl) respectively 6 (hexanoyl) or 12 (dodecanoyl) carbon atoms.

(56) 2-n-HD means that the R group contains an 2-n-hexyldecanoyl endgroup.

(57) M.sub.n, polymer: Number-average molecular weight of PCLA block as determined with GPC

(58) PCLA/PEG: the ratio of PCLA to PEG

(59) CL/LA: the ratio of -caprolactone to L-lactide

(60) m/m: the ratio of the first monomer to the second monomer in the B block

(61) PDI: polydispersity index according to GPC

(62) T.sub.g: glass transition temperature (midpoint) according to DSC

(63) Tm: Melting temperature according to DSC

(64) Degree of modification stands for number of aliphatic end-groups (R) after polymer modification. When the degree of modification is indicated as, it means that R=H in the formula RBABR. When the degree of modification is 2, it means that R is a fatty acid residue comprising a number of C atoms.

(65) Experiment 2; Testing of Polymers for Injectability.

(66) The polymers listed in Tables 1A and B have been tested for injectability and viscosities have been measured at 20 C. and 37 C. Results are listed in Tables 2A and B.

(67) TABLE-US-00003 TABLE 3A Results injectability and rheology Ejection time (seconds) at 20 C. Viscosity (Pa .Math. s) # Polymer composition 21 G (0.1 ml) 25 G (0.1 ml) 27 G (0.1 ml) At 20 C. At 37 C. 1 PEG200(cap.sub.50-lac.sub.50).sub.5.0 7 39 >120 7.6 1.6 2 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C3 6 33 >120 6.2 1.2 3 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C6 5 25 >120 4.8 1.1 4 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C12 3 21 >120 4.0 1.0 5 PEG200(cap.sub.50-lac.sub.50).sub.7.5 20 100 >120 19 3.0 6 PEG200(cap.sub.50-lac.sub.50).sub.7.5-C3 12 80 >120 16 3.2 7 PEG200(cap.sub.50-lac.sub.50).sub.7.5-C6 10 48 >120 7.3 2.4 8 PEG200(cap.sub.50-lac.sub.50).sub.10 57 >120 Not ejectable* 60 9.8 9 PEG200(cap.sub.50-lac.sub.50).sub.10-C3 55 >120 Not ejectable* 53 8.8 10 PEG200(cap.sub.50-lac.sub.50).sub.10-C6 34 >120 Not ejectable* 36 7.4 11 PEG600(cap.sub.50-lac.sub.50).sub.1.0 1 6 23 1.3 0.4 12 PEG600(cap.sub.50-lac.sub.50).sub.1.0-C3 1 5 17 0.9 0.3 13 PEG600(cap.sub.50-lac.sub.50).sub.1.0-C6 1 5 16 0.5 0.3 14 PEG600(cap.sub.50-lac.sub.50).sub.2.0 5 26 >120 6.3 1.4 15 PEG600(cap.sub.50-lac.sub.50).sub.2.0-C3 4 25 >120 5.1 1.3 16 PEG600(cap.sub.50-lac.sub.50).sub.2.0-C6 3 20 >120 3.9 1.1 17 PEG600(cap.sub.50-lac.sub.50).sub.4.0 43 >120 Not ejectable* 56 10.3 18 PEG600(cap.sub.50-lac.sub.50).sub.4.0-C3 37 >120 Not ejectable* 36 9.2 19 PEG600(cap.sub.50-lac.sub.50).sub.4.0-C6 29 >120 Not ejectable* 33 7.2 20 PEG1000(cap.sub.50-lac.sub.50).sub.0.5 >120 >120 Not ejectable* 117 0.4 21 PEG1000(cap.sub.50-lac.sub.50).sub.0.5-C3 1 5 52 2.0 0.3 22 PEG1000(cap.sub.50-lac.sub.50).sub.0.5-C6 1 4 16 3.2 0.3 23 PEG200(cap.sub.75-lac.sub.25).sub.5.0 1 9 34 1.9 0.6 24 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C3 1 7 27 1.8 0.6 25 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C6 1 6 24 1.6 0.4 26 PEG200(cap.sub.25-lac.sub.75).sub.5.0 >120 >120 Not ejectable* 92 7.7 27 PEG200(cap.sub.25-lac.sub.75).sub.5.0-C3 50 >120 Not ejectable* 61 6.6 28 PEG200(cap.sub.25-lac.sub.75).sub.5.0-C6 33 >120 Not ejectable* 38 5.0 29 PEG200(cap.sub.75-lac.sub.25).sub.7.5-C3 4 24 >120 4.3 N.A. 30 PEG200(cap.sub.75-lac.sub.25).sub.7.5-C6 2 16 >120 2.8 N.A. *not ejectable: no polymer was observed at the tip of the needle during the experiment.

(68) TABLE-US-00004 TABLE 4B Results injectability and rheology Ejection time (seconds) at 20 C. Viscosity (Pa .Math. s) # Polymer composition 21 G (0.1 ml) 25 G (0.1 ml) 27 G (0.1 ml) At 20 C. At 37 C. 31 PEG200(cap.sub.75-lac.sub.25).sub.3.0-HD 2 10 <120 1.7 0.50 32 PEG200(cap.sub.50-lac.sub.50).sub.5.0-HD 3 13 50 2.3 0.63 33 PEG400(cap.sub.60-lac.sub.40).sub.5.0-succinic 54 N.A. N.A. 93 15 34 PEG200(cap.sub.40-gly.sub.30-lac.sub.30).sub.5.0-HD 24 41 N.A. 27.9 4.7 35 PEG200(cap.sub.50-gly.sub.50).sub.5.0-HD 11 41 N.A. 11.9 2.6 36 PEG200(diox50-TMC50)5.0-HD 21 41 N.A. 27 4.8 37 PEG200(cap.sub.50-TMC.sub.50).sub.5.0 9 N.A. N.A. 10 2.8 38 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C3 6 N.A. N.A. 6.6 1.9 39 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C6 6 N.A. N.A. 5.9 1.8 40 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-C12 6 N.A. N.A. 6.7 2.1 41 PEG200(cap.sub.50-TMC.sub.50).sub.5.0-HD 3 13 51 2.7 0.82 42 PEG200(cap.sub.50-val.sub.50).sub.5.0 1 4 11 0.43 0.18 43 PEG200(cap.sub.50-val.sub.50).sub.5.0-C3 2 7 23 1.0 0.40 44 PEG200(cap.sub.50-val.sub.50).sub.5.0-C6 1 5 21 1.0 0.40 45 PEG200(cap.sub.50-val.sub.50).sub.5.0-C12 2 10 N.A. 1.8 0.70 46 PEG200(cap.sub.50-val.sub.50).sub.5.0-HD 2 12 N.A. 2.2 0.80 47 PEG200(cap.sub.75-val.sub.25).sub.5.0-C3 1 8 N.A. 1.8 0.53 48 PEG200(cap.sub.75-val.sub.25).sub.5.0-C6 2 9 N.A. 2.5 0.58 49 PEG200(cap.sub.75-val.sub.25).sub.5.0-C12 Not eject N.A. N.A. 16 0.83 50 PEG200(cap.sub.75-lac.sub.25).sub.5.0-HD 4 23 41 3.9 1.2 51 PEG200(cap.sub.25-val.sub.75).sub.5.0-C3 2 8 N.A. 2.0 0.51 52 PEG200(cap.sub.25-val.sub.75).sub.5.0-C6 1 7 N.A. 1.8 0.52 53 PEG200(cap.sub.50-diox.sub.50).sub.5.0 2 11 46 2.1 0.63 54 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C2 2 11 43 2.1 0.62 55 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C6 1 3 12 0.62 0.23 56 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C12 1 5 20 0.87 0.32 57 PEG200(cap.sub.50-diox.sub.50).sub.5.0-HD 1 8 23 1.0 0.34

(69) A second set of polymers was prepared using monomers with a low Tg and Tm (melting point) in combination with -caprolactone (see also table 1B). The combination of -caprolactone with for example dioxanone or -valerolactone gives low viscous and excellent injectable copolymers.

(70) Large differences were observed in ejection times depending on the total polymer molecular weight and the molecular composition. As shown in Table 2, the end-group (C6 or C12) had a significant effect on the ejection time. In general, polymers with end-group R=H show a low ejectability and relatively high viscosity. C3-endcapped polymers had better ejectability properties and C6 or C12 modified polymers had the best ejectability properties and the lowest viscosity, compared to unmodified ones (with R=H).

(71) The composition of the PCLA-block (B-block) is also of great importance. For example: a polymer with a composition of PEG200(cap.sub.25-lac.sub.75).sub.5.0-C3 was not ejectable, while changing the composition to PEG200(cap.sub.75-lac.sub.25).sub.5.0-C3 resulted in a very nice ejectable polymer. The viscosity is dropping when caprolactone is the major component of the PCLA-block. The inventors believe that this has to do with the lower T.sub.g of caprolactatee monomer units compared to the more rigid lactate monomer units. Increasing the temperature to 37 C. results in less viscous polymers. Ejections at 37 C. are much easier and significantly lower the ejection time for these polymers.

(72) As shown in Table 1 the thermal properties of the polymers were determined using DSC. Polymers composed with PEG1000 have a melting temperature around 20 C. These polymers crystallize in the refrigerator (4 C.) and even at ambient temperature. End-capping these polymers lowers the melting temperature, but not low enough to prevent crystallization. However, the copolymers may be warmed up to 37 C. prior to injection to melt the crystalline domains of the PEG. If preferred, said copolymers may be cooled to room temperature again prior to injection without immediate crystallization happens and with that without immediate increase in viscosity.

(73) The relation between the glass transition temperature (T.sub.g) and the viscosity of PEG200-derivatives is shown in FIG. 2. The lower the T.sub.g the lower the viscosity of the polymer. If the T.sub.g is lower than approx. 40 C. the polymers can be ejected through a thin needle of 25 G. A higher T.sub.g results in a higher viscosity and with that a worse ejectability. This may be circumvented by choosing for a higher ejection temperature (e.g. 37 C.) as is shown in FIG. 2, as well.

(74) The same trend is observed for the PEG600-derivatives (FIG. 3). Only the T.sub.g of these polymers should be lower than approx. 50 C. to allow ejection through a thin needle of 25 G at 20 C.

(75) Experiment 3: In-Vitro Release of Lidocane-HCl

(76) A selection of polymers were loaded with 1% lidocane-HCl (small hydrophilic API). A known amount of loaded polymer (250-350 mg) was transferred into small tubes (15 ml), followed by the addition of 5 mL PBS (pH=7.4; 52 mm; 300 mOsm; pre-warmed at 37 C.). The tubes were placed in a shaking incubator at 37 C.

(77) Release samples were taken during 7 days, at these time points buffer (600 l) was removed from the supernatant and replaced by pre-warmed PBS. The samples were analysed for its lidocaine content using UHPLC.

(78) In the first day small differences were observed between the three different polymers, composition PEG200(cap.sub.50-lac.sub.50).sub.5.0 (FIG. 4). The effect of an end-group was becoming more clear after 2 days. After 7 days the polymer with no end-group (R=H) showed a release of approx. 51%. Slower release of lidocane-HCl was observed with end-groups. A C3-end-group showed a release of approx. 28% and a C6-end-group showed a release of approx. 15% after 7 days.

(79) As shown in FIG. 5 similar results were obtained with polymers with composition PEG200(cap.sub.75-lac.sub.25).sub.5.0, whereas the polymer with no end-group (R=H) showed a lidocane-HCl release of approx. 47% after 7 days. The C3-endcapped showed a release of approx. 30%, a greater effect on the release was observed with the C6-endcapped polymer, which gave a release of approx. 18% after 7 days.

(80) Besides the influence of the end-groups on the release of lidocane-HCl also the effect of the polyester block length and monomer composition was determined (FIG. 6). In this experiment three polymers based on PEG200 with C6 end-groups but with different polyester block length or PCLA-ratio were compared. By varying these parameters small differences in release were observed. After 7 days approx. 18%-28% of lidocaine-HCl was released.

(81) The positive effect (=slower release) of the end-group was even more clear with polymer PEG600(cap.sub.50-lac.sub.50)1.0. No end-group (R=H) resulted in the release of 80% lidocane-HCl after 7 days, whereas the C3-endcapped version shows a release of 30% after 7 days (FIG. 7).

(82) Experiment 4: In-Vitro Release of Lysozyme

(83) Polymers were selected and loaded with 10% lysozyme. A known amount of loaded polymer (between the 250-350 mg of the loaded liquid polymer) was transferred into small tubes (15 ml), followed by the addition of 3 ml PBS (pH=7.4; 52 mm; 300 mOsm; pre-warmed at 37 C.). The tubes were placed in a shaking incubator at 37 C.

(84) Release samples were taken during 7 days, at these time points buffer (300 l) was removed from the supernatant and analysed for lysozyme release using a BCA protein assay. Directly after sampling pre-warmed fresh PBS (300 l) was added to continue the release study.

(85) FIG. 8 illustrates that during the first 3 days lysozyme was released much faster from the non-end-capped polymer PEG200(cap50-lac50)5.0 compared to the end-capped versions of the same polymer composition. After 3 days the release slows down for all formulations. This example demonstrates the beneficial effect of the end-group on reducing the burst release.

(86) FIG. 9 shows that a longer end-group gives more retention of lysozyme release. Polymer PEG200(cap50-lac50)7.5-C6 is a more viscous polymer (higher molecular weight), this also can provide more retention.

(87) Not only the composition of the PCLA-block or the molecular weight of the polymer is of great importance to control the release properties, but, as shown in FIG. 10, also the hydrophilic part (PEG block) has a huge effect. Longer PEG blocks give faster release in comparison to polymers with molecular weights in the same range and same PCLA composition.

(88) Experiment 5: Ex-Vivo Injection of Copolymer.

(89) Polymers were injected in a rat cadaver at 37 C. (rats were sacrificed 1 minute before injection; the rats were taken from another study and not sacrificed for the purpose of the injection studies). The polymers were loaded with a trace of methylene blue for better visualization. Immediately after injection, the skin of the rat was removed. To our surprise, a nice gummy depot was formed. Depots were retrieved and stored at room temperature. After 10 weeks the depots were still gummy.

(90) Experiment 6: Determination of Viscosities of Pharmaceutical Compositions

(91) A new set of liquid polymers was synthesised to measure the effect on the viscosity when these were loaded (1% w/w) with an API (lidocaine, lidocaine-HCl, Celecoxib or lysozyme). First a vial was charged with an known amount of polymer, followed by the addition of the appropriate API. The vials were stored at 37 C. for a few hours. In this time the API's dissolved into the polymer matrix, after which the samples were mixed using a spatula. Before measuring the viscosity (single measurement using the method as previous described), the samples were stored under ambient conditions for at least 24 hours. As depicted in Table 5, loading the polymers with 1% (w/w) API had not a significant effect on the viscosity.

(92) TABLE-US-00005 TABLE 5 Viscosity (Pa .Math. s) of polymers, at 20 C., with or without API (1% w/w) API content (1% w/w) Lido- No cane- Lido- Cele- Lyso- # Polymer composition API HCl cane coxib syme 1 PEG200(cap.sub.50-lac.sub.50).sub.5.0 8.4 8.6 8.4 8.5 7.7 2 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C3 6.4 6.0 6.4 7.0 6.0 3 PEG200(cap.sub.50-lac.sub.50).sub.5.0-C6 4.0 3.7 3.8 4.4 3.9 11 PEG600(cap.sub.50-lac.sub.50).sub.1.0 1.3 1.4 1.3 N.A. 1.2 12 PEG600(cap.sub.50-lac.sub.50).sub.1.0-C3 1.0 1.0 1.0 1.0 1.0 15 PEG600(cap.sub.50-lac.sub.50).sub.2.0-C3 5.1 5.3 5.0 N.A. 5.2 23 PEG200(cap.sub.75-lac.sub.25).sub.5.0 1.9 2.1 1.9 2.0 1.7 24 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C3 1.8 1.6 1.5 1.6 1.7 25 PEG200(cap.sub.75-lac.sub.25).sub.5.0-C6 1.6 1.5 1.5 N.A. 1.5

(93) Experiment 7.

(94) Different examples of RBABR copolymers have been prepared, and the thermal properties as well as viscosities have been determined.

(95) In all cases PEG is used as the A block. The B block has been varied with a combination of 1 to 3 different monomers from the group of monomers as depicted below:

(96) ##STR00001##

(97) Table 4 summarizes the thermal properties of the homopolymers of these monomers.

(98) TABLE-US-00006 TABLE 6 Properties of homopolymers Tg ( C.) Tm ( C.) -Caprolactone 60 60 Lactide 60 175 p-Dioxanone 10-0 110 Glycolide 35-40 225-230 -Valerolactone 67 60 Trimethylene carbonate 26-15 36

(99) Table 4 shows that the monomers -caprolactone and -valerolactone will support the beneficial thermal properties of the RBABR copolymers, and also p-dioxanone and trimethylene carbonate have reasonable low T.sub.g values. At the same time it is important to avoid the formation of crystalline domains in the RBABR copolymer. Large amounts of lactide and glycolide should be avoided due to the rigid structure of these monomers as demonstrated by the high Tg and Tm values of the homopolymers.

(100) The thermal properties of the A block are also of important. In case the A block is PEG the following relation between mol weight and melting point can be found (table 5):

(101) TABLE-US-00007 TABLE 7 Melting points of PEG Polyethylene glycol mol weight Melting point ( C.) 200 65 600 17-22 1000 35-40 1250 40-45

(102) TABLE-US-00008 TABLE 8 Viscosity properties using other monomers Viscosity (Pa .Math. s) Thermal properties # Polymer composition At 20 C. At 37 C. Tg ( C.) Tm ( C.) 58 PEG200(cap).sub.1.0 0.46 0.09 80 19 59 PEG200(cap).sub.1.0-C3 0.16 0.13 81 20 60 PEG200(cap).sub.5.0 N.A.* N.A.* 77 40 61 PEG200(cap).sub.5.0-C6 N.A.* N.A.* 44 62 PEG200(DL-lactide).sub.5.0 N.A.* 101 6 63 PEG600(DL-lactide).sub.1.0 7.2 1.3 40 64 PEG600(DL-lactide).sub.2.0 289 19.2 25 65 PEG200(cap.sub.75-gly.sub.25).sub.5.0 3.7 1.0 57 66 PEG200(cap.sub.50-gly.sub.50).sub.5.0 26.3 5.8 41 67 PEG200(gly.sub.50-lac.sub.50).sub.5.0 N.A.* N.A.* 25 68 PEG200(valero.sub.50-lac.sub.50).sub.5.0 7.0 1.5 44 69 PEG200(cap.sub.40-lac.sub.30-gly.sub.30).sub.5.0 21.8 3.6 34 70 PEG200(cap.sub.40-lac.sub.30-gly.sub.30).sub.5.0- 12 2.3 42 C6 71 PEG200(cap.sub.25-diox.sub.75).sub.5.0 0.7 0.2 Not measured Not measured 72 PEG200(cap.sub.25-diox.sub.75).sub.5.0-C6 0.4 0.2 Not measured Not measured 73 PEG200(cap.sub.50-diox.sub.50).sub.5.0 2.0 0.7 Not measured Not measured 74 PEG200(cap.sub.50-diox.sub.50).sub.5.0-C6 0.7 0.3 Not measured Not measured 75 PEG200(cap.sub.75-diox.sub.25).sub.5.0 1.6 0.6 Not measured Not measured 76 PEG200(cap.sub.75-diox.sub.25).sub.5.0-C6 0.8 0.3 Not measured Not measured *Not available, not able to suck up the polymer with a syringe (without needle).

(103) Using only -caprolactone as hydrophobic component results in a very liquid polymer with a low T.sub.g (80 C.) at ambient temperature. Storage in the fridge solidifies the polymer due to its higher melting temperature. The polymers with only DL-lactide (50/50 D/L ratio) have a high viscosity due to their relatively high T.sub.g varying from 6 to 40 C.

(104) Two polymers were made with PEG200, -caprolactone and glycolide with different composition of the hydrophobic block, a higher amount (75%) of -caprolactone reduces the T.sub.g and thus lowers the viscosity. A combination of glycolide and lactide as hydrophobic block is not a good match due to the high T.sub.g of both monomers (see table 4) and gives a very viscous, almost solid polymer.

(105) Another monomer with a low Tg (-valerolactone) was introduced, this in combination with lactide and PEG200 resulted in a polymer with relatively low viscosity. This polymer is comparable with PEG200(cap.sub.50-lac.sub.50).sub.5.0, due to the lower T.sub.g of -valerolactone the viscosity of this polymer is slightly lower.

(106) Also a combination of three monomers is possible (PEG200(cap.sub.40-lac.sub.30-gly.sub.30).sub.5.0). Chemical modification to a C6-endgroup reduces the T.sub.g and the viscosity.

(107) It has been found that a combination of two monomers in the B block that have a low Tg gives RBABR block copolymers having a low viscosity and excellent injectability. For example the use of -caprolactone and dioxanon as monomeric units for the B-block gives excellent RBABR block copolymers (see samples 44-49).

(108) Experiment 8; State of the Art Polymers

(109) A number of state of the art polymers have been prepared from different prior art references. The viscosity of the neat polymers has been measured at 20 C.

(110) TABLE-US-00009 TABLE 7 viscosities of prior art copolymers. Mean visco at Reference Polymer 20 C. (Pa .Math. s) EP2343046; example 1 PEG1500(L-Lac.sub.50- >4000 TMC.sub.50)1.2 U.S. Pat. No. 7,740,877B2: PEG1500(Cap.sub.50-L- 141 example 2 Lac.sub.50)1.2-C6 WO2012/131104: example 1 PEG1500(cap.sub.90-lac.sub.10).sub.2.2- >2000000 C2 Angew. Chem. Int. Ed. PEG1000(DL-lac.sub.67- 3090 2006, 45, 2232-2235: Gly.sub.33)1.8-C2 example B

(111) All polymers show crystallinity, and have a melting temperature above 20 C. In order to be able to measure viscosity at 20 C., the samples have been melted first at 50 C., and subsequently cooled down to 20 C. After 4 minutes conditioning at 20 C., the viscosity has been measured of the samples. The sample from EP2343046 and WO2012/131104 crystallized during the measurement and give very high viscosity values.

(112) All samples have high viscosities relative to the BAB block copolymers according to the invention.