Co-crystals of duloxetine and COX-INHIBITORs for the treatment of pain

1. A co-crystal comprising duloxetine either as a free base or as its physiologically acceptable salt and at least one co-crystal former selected from the group of COX-INHIBITORs other than Naproxen.

2. A co-crystal according to claim 1 , wherein the co-crystal former or at least one of the co-crystal formers has at least one functional group from the group consisting of ether, thioether, alcohol, thiol, aldehyde, ketone, thioketone, nitrate ester, phosphate ester, thiophosphate ester, ester, thioester, sulfate ester, carboxylic acid, phosphonic acid, phosphinic acid, sulfonic acid, amide, primary amine, secondary amine, ammonia, tertiary amine, thiocyanate, cyanamide, oxime, nitrile, diazo, organohalide, nitro, s-heterocyclic ring, thiophene, n-heterocyclic ring, pyrrole, o-heterocyclic ring, furan, epoxide, peroxide, hydroxamic acid, imidazole, and pyridine.

3. A co-crystal according to claim 1 , wherein the co-crystal former or at least one of the co-crystal formers is chosen in such a way that if compared to either duloxetine alone or to a mixture of duloxetine and the corresponding active agent/s

a) the solubility of the co-crystal is increased; and/or

b) the dose response of the co-crystal is increased; and/or

c) the efficacy of the co-crystal is increased; and/or

d) the dissolution of the co-crystal is increased; and/or

e) the bioavailability of the co-crystal is increased; and/or

f) the stability of the co-crystal is increased; and/or

g) the hygroscopicity of the co-crystal is decreased; and/or

h) the form diversity of the co-crystal is decreased; and/or

i) the morphology of the co-crystal is modulated.

4. The co-crystal according to claim 1 , wherein the co-crystal former or one of the co-crystal formers is selected from

Acetylsalicylic acid, Diflunisal, Ethenzamide, Salicylamide, Triflusal, Fosfosal, Benorylate, Paracetamol, Propacetamol, Phenidine, Etofenamate, Flufenamic acid, Meclofenamic acid, Mefenamic acid, Niflumic acid, Tolfenamic acid, Acemetacin, Oxametacin, Glucametacin, Proglumetacin, Bufexamac, Diclofenac, Alcofenac, Aceclofenac, Indomethacin, Lonazolac, Sulindac, Tolmetin, Amtolmetin guacil, Mofezolac, Bromfenac, Nabumetone, Fentiazac, Felbinac, Flurbiprofen, Flurbiprofen axetil, Ibuprofen, Ketoprofen, Tiaprofenic acid, Zaltoprofen, Pirprofen, Fenoprofen, Vedaprofen, Nepafenac, Amfenac, Clidanac, Metamizol, Propylphenazone, Kebuzone, Mofebutazone, Oxyphenbutazone, Phenylbutazone, Apazone, Isoxicam, Lornoxicam, Piroxicam, Tenoxicam, Ketorolac, Proquazone, Oxaprozine, Ditazole, Etodolac, Meloxicam, Nimesulide, Celecoxib, Etoricoxib, Lumiracoxib, Parecoxib, Rofecoxib, Valdecoxib, Cimicoxib; Bermoprofen; Pelubiprofen; Tenosal; Aceneuramic acid; Pirazolac; Xinoprofen; Flobufen; Anirolac; Zoliprofen; Bromfenac; Pemedolac; Dexpemedolac; Bindarit; Romazarit; Tiaprofenic acid; Ketorolac; Fenbufen; Fenoprofen; Flobufen; Oxaprozin; or their stereoisomers, salts or metabolites.

5. The co-crystal according to claim 1 , wherein the co-crystal former is tolmetin or its salts thereof.

6. A co-crystal according to claim 5 , wherein the molecular ratio between duloxetine and tolmetin is 1:2.

7. A co-crystal according to claim 6 , characterized in that the endothermic sharp peak corresponding to the melting point has an onset at 111° C.

8. Co-crystal according to claim 6 , characterized in that it shows a X-Ray powder diffraction pattern with peaks expressed in d-Value in A at 13.774, 12.845, 11.510, 9.146, 8.909, 8.462, 7.662, 6.856, 6.435, 6.329, 6.019, 5.881, 5.715, 5.571, 5.259, 5.010, 4.928, 4.888, 4.569, 4.443, 4.274, 4.216, 4.136, 4.032, 3.951, 3.896, 3.830 and 3.757.

9. Process for the production of a co-crystal according to claim 1 comprising the steps of:

either (Alternative I):

(a) dissolving or suspending a co-crystal former in a solvent; and

(b) heating the solution or dispersion to a temperature above ambient temperature and below the boiling point of the solution or dispersion;

(c) dissolving together with, or after, or before step (a) duloxetine either as a free base or as a salt in a solvent,

(d) adding the solution of (c) to the heated solvent of (b) and mixing them;

or (Alternative II):

(a) dissolving or suspending a co-crystal former and duloxetine in a solvent; and

(b) heating the solution or dispersion to a temperature above ambient temperature and below the boiling point of the solution or dispersion;

(d) adding a solvent to the heated solvent of (b) and mixing them;

followed by (for both Alternatives I and II)

(e) cooling the mixed solution/dispersion of step

(d) to ambient temperature;

(f) filtering-off the resulting co-crystals.

10. Pharmaceutical composition characterized in that it comprises a therapeutically effective amount of the co-crystal according to claim 1 in a physiologically acceptable medium.

11. A method for the treatment of pain in a subject in need thereof which comprises administering to the subject the co-crystal according to claim 1 .

12. A co-crystal according to claim 2 , wherein the co-crystal former or at least one of the co-crystal formers is chosen in such a way that if compared to either duloxetine alone or to a mixture of duloxetine and the corresponding active agent/s

a) the solubility of the co-crystal is increased; and/or

b) the dose response of the co-crystal is increased; and/or

c) the efficacy of the co-crystal is increased; and

d) the dissolution of the co-crystal is increased; and/or

e) the bioavailability of the co-crystal is increased; and/or

f) the stability of the co-crystal is increased; and/or

g) the hygroscopicity of the co-crystal is decreased; and/or

h) the form diversity of the co-crystal is decreased; and/or

i) the morphology of the co-crystal is modulated.

13. The co-crystal according to claim 3 , wherein the co-crystal former or one of the co-crystal formers is selected from

Acetylsalicylic acid, Diflunisal, Ethenzamide, Salicylamide, Triflusal, Fosfosal, Benorylate, Paracetamol, Propacetamol, Phenidine, Etofenamate, Flufenamic acid, Meclofenamic acid, Mefenamic acid, Niflumic acid, Tolfenamic acid, Acemetacin, Oxametacin, Glucametacin, Proglumetacin, Bufexamac, Diclofenac, Alcofenac, Aceclofenac, Indomethacin, Lonazolac, Sulindac, Tolmetin, Amtolmetin guacil, Mofezolac, Bromfenac, Nabumetone, Fentiazac, Felbinac, Flurbiprofen, Flurbiprofen axetil, Ibuprofen, Ketoprofen, Tiaprofenic acid, Zaltoprofen, Pirprofen, Fenoprofen, Vedaprofen, Nepafenac, Amfenac, Clidanac, Metamizol, Propylphenazone, Kebuzone, Mofebutazone, Oxyphenbutazone, Phenylbutazone, Apazone, Isoxicam, Lornoxicam, Piroxicam, Tenoxicam, Ketorolac, Proquazone, Oxaprozine, Ditazole, Etodolac, Meloxicam, Nimesulide, Celecoxib, Etoricoxib, Lumiracoxib, Parecoxib, Rofecoxib, Valdecoxib, Cimicoxib; Bermoprofen; Pelubiprofen; Tenosal; Aceneuramic acid; Pirazolac; Xinoprofen; Flobufen; Anirolac; Zoliprofen; Bromfenac; Pemedolac; Dexpemedolac; Bindarit; Romazarit; Tiaprofenic acid; Ketorolac; Fenbufen; Fenoprofen; Flobufen; Oxaprozin; or their stereoisomers, salts or metabolites.

14. The co-crystal according to claim 4 , wherein the co-crystal former is tolmetin or its salts thereof.

15. The co-crystal of claim 2 , wherein the co-crystal former or at least one of the co-crystal formers has at least one functional group from the group consisting of alcohol, thiol, ester, carboxylic acid, primary amine, secondary amine, tertiary amine.

16. The co-crystal of claim 2 , wherein the co-crystal former or at least one of the co-crystal formers has at least one functional group being a carboxylic acid.

17. The method of claim 11 , wherein the pain is selected from acute pain, chronic pain, neuropathic pain, hyperalgesia, allodynia or cancer pain.