Microemulsions and Lyotropic Liquid Crystals of Lecithin as Systems for Transdermal Drug Delivery

Reverse microemulsions in the lecithin-oleic acid-paraffin oil-avocado oil-tea tree essential oil-water system and lamellar liquid crystals in the lecithin-avocado oil-tea tree essential oil-water system were studied as systems for transdermal drug delivery. Oil- and water-soluble substances, as well as substances that are poorly soluble in water and oil in the form of solid-phase particles, can be introduced into liquid crystals in concentrations of a few percent. Oil-soluble substances can be introduced into reverse microemulsions in concentrations of a few percent and water-soluble substances can be introduced in concentrations of tenths of a percent. The dialysis method showed that the rate of release of water-soluble substances from the reverse microemulsion containing 4.8 wt % water is approximately 2.5 times higher than that from the lamellar liquid crystal containing 15 wt % water. This is explained by the fact that the viscosity of liquid crystals is more than 100 times higher than the viscosity of microemulsions.