Formulations for the treatment of pain
Formulations and methods are provided for the treatment of pain, and neuropathic pain in particular. The formulations are eutectic mixtures of a capsaicinoid and a local anesthetic agent and/or an anti-pruritic agent.
1. A substantially nonaqueous therapeutic formulation comprising a binary eutectic mixture of:
(a) a capsaicinoid having the structure of formula (I)
wherein R 1 is hydrogen, hydroxyl or methoxy, R 2 is hydroxyl or C 2 -C 6 alkoxycarbonyl, X is selected from
and R is selected from C 5 -C 11 alkyl, C 5 -C 11 alkenyl, C 11 -C 23 cis-alkenyl, C 11 -C 23 alkynyl, and C 11 -C 23 alkadienyl, provided that the capsaicinoid is other than capsaicin, wherein the capsaicinoid represents about 10 wt. % to about 70 wt. % of the formulation; and
(b) a second active agent effective to decrease at least one side effect associated with capsaicin monotherapy, said second agent existing as a solid at 25° C., and wherein said second agent is a local anesthetic agent selected from the group consisting of amylocaine, articaine, benzocaine, bupivacaine, butacaine, 2-chloroprocaine, cinchocaine, dexivacaine, diamocaine, dibucaine, etidocaine, ketocaine, lidocaine, mepivacaine, oxybuprocaine, parethoxycaine, prilocaine, procaine, propanocaine, proparacaine, propoxycaine, pyrrocaine, risocaine, rodocaine, ropivacaine, tetracaine, and combinations thereof; and
wherein the formulation contains less than 5 wt. % water.
2. The formulation of claim 1 , wherein the capsaicinoid is selected from resiniferatoxin, N-vanillyl-alkadienamides, N-vanillyl-alkanedienyls, N-vanillyl-monounsaturated alkenamides, N-vanillylsulfonamides, and hydroxyphenylacetamides.
3. The formulation of claim 2 , wherein the capsaicinoid is an N-vanillyl monounsaturated alkenamide.
4. The formulation of claim 1 , wherein the local anesthetic agent is lidocaine.
5. The formulation of claim 1 , wherein the local anesthetic agent is tetracaine.
6. The formulation of claim 1 , wherein the capsaicinoid represents about 40 wt. % to about 70 wt. % of the formulation.
7. A method for treating a patient suffering from pain, comprising administering to the patient a therapeutically effective amount of the formulation of claim 1 .
8. The method of claim 7 , wherein the formulation is administered topically.
9. The method of claim 8 , wherein the pain is caused by inflammation of joints, tendons, nerves, or muscle.
10. The method of claim 7 , wherein the pain is caused by cancer.
11. The method of claim 7 , wherein the pain is neuropathic pain.
12. The formulation of claim 1 , wherein the formulation contains less than 1 wt. % water.
13. The formulation of claim 1 , wherein the formulation is substantially free of additional components other than the capsaicinoid and the local anesthetic agent.