Liquisolid systems and aspects influencing their research and development

Many modern drugs are poorly water soluble substances, which causes difficulties in the development of solid dosage forms with sufficient bioavailability. Preparation of liquisolid systems (LSS) is a novel technique for improving solubility, dissolution and bioavailability of such drugs. The basic principle of LSS preparation is conversion of the drug in liquid state into a free-flowing, compressible, dry powder through its absorption into suitable excipients - porous carriers (aluminometasilicates, microcrystalline cellulose), subsequently coated with material having high absorption capacity (silicon dioxide commonly known as colloidal silica). LSS exhibit advantages such as lower production costs compared to soft capsules, simple processing and enhanced drug release. The main benefit is higher bioavailability of the liquid drug, caused by a large surface area available for absorption. The article tries to clarify specific aspects connected with the formulation of LSS: properties of excipients (surface area, absorption capacity), variables related to the processing (solubility, liquid load factor) and dosage form evaluation.