Patent ID: 7157099

Claim:
A water-in-oil (w/o) microemulsion comprising: a) up to 20% of an internal hydrophilic aqueous phase containing a therapeutically active hydrophilic compound; b) 30 to 98% of a hydrophobic external phase selected from esters of C 8 –C 20 saturated or unsaturated carboxylic acids with a C 2 –C 8 branched or linear alcohol residue or mono, di- and triglycerides of C 8 –C 20 fatty acids; c) up to 50% of a surfactant in admixture with a co-surfactant, said surfactant being selected from natural or synthetic glycerophospholipids containing residues of C 4 –C 20 saturated or unsaturated carboxylic acids having as phosphoester moiety a residue of choline, ethanolamine, serine, glycerol, and said co-surfactant being selected from C 8 –C 20 fatty acids or C 2 –C 12 alcohols, and wherein the surfactant/co-surfactant ratio is ≧2; wherein the aqueous phase has a pH between 4.5 and 7.5.