SOLID DISPERSIONS: A REVIEW ON DRUG DELIVERY SYSTEM AND SOLUBILITY ENHANCEMENT

Solid dispersions, defined as the dispersion of one or more active pharmaceutical ingredient in a carrier at solid state and an efficient technique to improve dissolution of poorly water-soluble drugs to enhance their bioavailability. Poor water solubility is one of the major problems for the various types of drugs and various approaches have been introduced for the enhancement of solubility of such drugs. The solubility behaviour of drugs remains one of the most challenging aspects in formulation development. The number of poor water soluble compounds has dramatically increased. Currently only 10-12% of new drug candidates have both high solubility and high permeability. More than 60-65% of potent drug products suffer from poor water solubility.  Solid dispersions have attracted considerable interest as an efficient means for improving the dissolution rate and hence the bioavailability of a range of hydrophobic drugs. Compared to conventional formulations such as tablets or capsules, solid dispersions which can be prepared by various methods have many advantages. Few of the aspects are to be considered for the preparation of solid dispersions, such as selection of carrier and methods of physicochemical characterization.  In this review, an overview on solid dispersions in general will be given with emphasis on the various types of solid dispersions, manufacturing processes, characterization, advantages, disadvantages and the application of the solid dispersions, challenges in formulation of solid dispersion dosage forms, and various types of marketed preparations.