Liquid Crystals of Lecithin as Drug Carriers

Abstract
Lecithin is a biocompatible, non-toxic surfactant, usually obtained from plant materials. It is the most commonly used is soy lecithin. In ternary and multicomponent systems, including lecithin, water and various natural and synthetic oils, as well as other components, lamellar (L_α) and reverse hexagonal (H_II) phases are most often found. The existence of L_α and H_II phases at temperatures close to room temperature is shown in the systems containing soy lecithin, water and the following components: cyclohexane, limonene, isopropyl palmitate, diacylglycerides from sunflower oil, glycerol trioleate, oleic acid, linoleic acid, palmitic acid, polyethylene glycol PEG-400, Tween-80 in combination with isopropyl myristate. The presence of single L_α phase is demonstrated in the systems containing soy lecithin, water and components such as decane, soybean oil, propylene glycol in combination with vaseline oil, short chain alcohols and medium chain triacylglycerides (C₈-C₁₀), Tween-80 in combination with butanol-1 and isopropyl palmitate. The existence of the reverse hexagonal phase is shown for the system of soy lecithin – 1,2-propylene glycol – castor oil – water (water : propylene glycol mass ratio of 1:1). The use of L and H_II phases of lecithin as carriers of oil- and water-soluble biologically active substances: ascorbyl palmitate, acetylhexapeptide-3, dihydromyricetin, curcumin, tetrahydrobiopterin is described. It is shown that commercial lecithin preparations with low content of the main substance, including phospholipid concentrates, can be used to obtain liquid crystals. Lamellar liquid crystals in the systems lecithin (phospholipid concentrate) – vaseline oil – water and lecithin (phospholipid concentrate) – fatty vegetable oil – essential oil – water are proposed as carriers of biologically active substances.

Keywords: lecithin, phospholipids, lyotropic liquid crystals, phase diagrams, nanocarriers, drug delivery