Volatile anesthetic compositions and methods of use

Abstract

The present invention provides methods for reducing pain in a subject in need thereof by delivering a volatile anesthetic in a solution or an emulsion that can additionally include an extractive solvent in an amount effective to reduce pain without substantially interfering with motor function. Chronic or acute pain may be treated, or the volatile anesthetic may be delivered as a regional anesthetic to a subject to anesthetize a portion of the subject prior to surgery. Dosing regimes including a one-time administration, continuous and/or periodic administration are contemplated.

1 .- 323 . (canceled) 
     
     
         324 . A method for reducing pain in a subject in need thereof, the method comprising delivering to the subject, by a route other than orally, intravenously or by inhalation, at least one selected from the group consisting of:
 a volatile anesthetic dissolved in a solution in an amount effective to reduce pain, wherein the solution further comprises an extractive solvent in an amount effective to reduce volatility of the volatile anesthetic, wherein the solution is a component of an emulsion;   a volatile anesthetic emulsion, wherein the volatile anesthetic is in an amount effective to reduce pain;   a liposome suspension comprising a volatile anesthetic in an amount effective to reduce pain;   a volatile anesthetic dissolved in a solution in an amount effective to reduce pain, and wherein the solution further comprises an extractive solvent in an amount effective to reduce volatility of the volatile anesthetic, wherein the composition further comprises a solubilizing agent; and   a microdroplet suspension comprising a sphere of a volatile anesthetic surrounded by a stabilizing layer of lipid in an amount effective to reduce pain.   
     
     
         325 . The method of  claim 324 , wherein the extractive solvent is at least one selected from the group consisting of dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone (NMP), dimethylisosorbide, ethanol, propanol, and isopropanol. 
     
     
         326 . The method of  claim 324 , wherein the volatile anesthetic is selected from the group consisting of isoflurane, halothane, enflurane, sevoflurane, desflurane, methoxyflurane, and any mixtures thereof. 
     
     
         327 . The method of  claim 324 , wherein the volatile anesthetic is delivered by at least one route from the group selected from intrathecally, epidurally, transdermally, topically, mucosally, buccally, rectally, vaginally, intramuscularly, subcutaneously, by local skin infiltration, and in a nerve block procedure. 
     
     
         328 . The method of  claim 324 , wherein the subject is human or a non-human animal. 
     
     
         329 . A pharmaceutically acceptable composition comprising at least one selected from the group consisting of:
 a pharmaceutically effective amount of a volatile anesthetic dissolved in an aqueous solution in an amount effective to reduce pain, wherein the solution further comprises an extractive solvent in an amount effective to reduce volatility of the volatile anesthetic, and wherein the solution is a component of an emulsion;   a pharmaceutically effective amount of a volatile anesthetic emulsion, wherein the volatile anesthetic is in an amount effective to reduce pain;   a pharmaceutically acceptable amount of a liposome suspension comprising a volatile anesthetic in an amount effective to reduce pain;   a pharmaceutically acceptable amount of a volatile anesthetic dissolved in a solution in an amount effective to reduce pain, wherein the solution further comprises an extractive solvent in an amount effective to reduce volatility of the volatile anesthetic; and wherein the composition further comprises a solubilizing agent; and   a pharmaceutically acceptable amount of a microdroplet suspension comprising a microdroplet suspension comprising a sphere of a volatile anesthetic in an amount effective to reduce pain and surrounded by a stabilizing layer of a phospholipid;   
       wherein the composition further comprises a pharmaceutically acceptable excipient. 
     
     
         330 . The composition of  claim 329 , wherein the extractive solvent is at least one selected from the group consisting of dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone (NMP), dimethylisosorbide, ethanol, propanol, and isopropanol. 
     
     
         331 . The composition of  claim 329 , wherein the volatile anesthetic is selected from the group consisting of isoflurane, halothane, enflurane, sevoflurane, desflurane, methoxyflurane, and any mixtures thereof. 
     
     
         332 . The composition of  claim 329 , which is formulated for administration by a route selected from the group consisting of intrathecally, epidurally, transdermally, topically, mucosally, buccally, rectally, vaginally, intramuscularly, subcutaneously, by local skin infiltration, and in a nerve block procedure.