Lecithin Microemulsions as Drug Carriers

The paper describes examples of microemulsions based on a well-known biocompatible surfactant, lecithin, and the possibilities of their use as drug carriers. The main problem encountered when developing lecithin microemulsions is the search for suitable cosurfactants. Molecules with short alkyl chains (4–5 C atoms) and relatively large polar “head,” such as short-chain aliphatic alcohols, acids, and amines are most suitable as cosurfactants for the preparation of lecithin microemulsions. Therewith, high concentrations of the cosurfactants (the cosurfactant : lecithin weight ratio usually is 1 : 1) are necessary. Most often, ethanol, n-propanol, or n-butanol are used as cosurfactants for the preparation of lecithin microemulsions in various natural and synthetic oils. To replace toxic alcohols with less toxic components, other well-known surfactants may be added to lecithin microemulsions. They are, e.g., Brij 96V (poly(ethylene glycol) oleate), Tween 80 (polyoxyethylene-20-sorbitan monooleate), Tween 20 (polyoxyethylene-20-sorbitan monolaurate). Triton X-100 (tert-octylphenyl ether of poly(ethylene glycol)) or oleic acid. Composites based on lecithin microemulsions have been described as means for local anesthesia and delivery of vitamins, as well as agents with anti-inflammatory, antifungal, anticancer, and wound healing effects. The considered examples show the promise of the study and development of lecithin microemulsions as drug carriers.