Patent ID: 8324274

Claim:
A drug delivery system for administration of at least one pharmaceutically active substance that is a cationic amphiphile by itself, which pharmaceutically active substance is present in the drug delivery system in particles of a complex between said pharmaceutically active substance and a sodium salt of the methyl ester of N-all-trans-retinoyl cysteic acid, a sodium salt of methyl ester of N-13-cis-retinoyl cysteic acid, or a combination thereof, said particles of said complex having an effective average particle size of less than about 50 nm, wherein the particles of said complex are essentially amorphous; the particles of said complex are entrapped in nanoparticles formed of a sodium salt of the methyl ester of N-all-trans-retinoyl cysteic acid, sodium salt of methyl ester of N-13-cis-retinoyl cysteic acid, or a combination thereof; and the weight-to-weight ratio of said sodium salt of methyl ester of N-all-trans-retinoyl cysteic acid, sodium salt of methyl ester of N-13-cis-retinoyl cysteic acid, or combination thereof, to the weight of said complex is in the range from about 0.5:1 to about 20:1.