Attempts and outcomes of liquisolid technology: An updated chronological compilation of innovative ideas and adjuvants in the field

Introduction The pharmaceutical goal of developing any oral dosage form is to carry most of the active pharmaceutical ingredient to the blood and if the dosage form is in solid state the primary concern falls on the solubility of the drug in GIT (1). Overall estimate reveals that around 40% of the developed molecules exhibit poor water solubility, which lead to poor bioavailability and high dropout rate from the drug discovery and development process (2). On the other hand about 15% of the druglike compounds and 40% of lead optimization compounds are insoluble at a concentration less than or equal to 20μg/ml. Such drugs tend to get eliminated from the gastrointestinal tract before they get fully dissolved as well as absorbed into the systemic circulation (3). The solubility/dissolution of a drug substance can be mainly altered at two different levels, through material engineering of the drug substance or through formulation approaches (4). Several methods had been employed to enhance the dissolution of the drugs having low solubility, such as salt formation (5), cosolvancy (6), complexation (7), micronization (8), melt sonocrystallization (9-10), lyophilization (11), steam-aided granulation (12), solubilization by surfactants (13), solid solution (14), inclusion of drug solution in soft gelatin capsule (15), are some of the major formulation tools which have been shown to enhance the dissolution characteristics of waterinsoluble drugs. On the other hand various approaches have been attempted to improve the bioavailability of Abstract It has been observed that most of the chemical entities have high lipophilicity and poor aqueous solubility, which result in poor bioavailability. In order to improve the bioavailability, the release behavior of such drugs should be improved. Although there are numerous techniques to handle solubility related issue, but they are expensive due to involvement of complicated equipments, advanced manufacturing operations that includes multiple and tedious steps. The liquisolid technology or powder solution technology is a promising technique for modifying the release characteristics of active pharmaceutical ingredients. As the liquisolid technology uses similar production processes as followed to develop a conventional tablet, but this technology to improve the release rate of poorly water soluble drugs is simple and cost effective The core concept of the technique involves, liquids such as solution/dispersion of poorly soluble drugs in a non-volatile solvent that is transformed into free flowing and desirable compression characteristics. To develop a fast-release liquisolid formulation, high amount of liquid vehicle is required while more effective tableting excipients with high liquid adsorption are needed to reduce the weight of the tablet. Simultaneously, this technology also has the capability to sustain the drug release and allow the development of sustained release formulation with desirable release kinetics. The present work deals with the chronological compilation and briefing of all the reported researches which involved the concept of underlined technology by the use of common as well as novel excipients to modify the release behavior of therapeutically active compounds.