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Abstract

Therapeutic effect of drug depends upon the bioavailability and the solubility of drugs molecules. Solubility is the most important parameter to achieve desired concentration of drug in systemic circulation for pharmacological response to be shown. It represent a fundamental concept in field of research. About 40% of drugs with market approval and nearly 90% of molecules in the discovery pipeline are poorly water-soluble. History: Generally, Poorly water soluble drugs often require high doses in order to reach the therapeutic plasma concentrations after oral administration. The drug with low aqueous solubility is the major problem in the formulation development of new chemical entities as well as generic development. The solubility of a substance fundamentally depends on the physical and chemical properties of the solute and solvent as well as on pressure, temperature and also changes to the pH of the solution. Poor solubility is an ongoing challenge in pharmaceutical development. A drug must be in solution form for it to be absorbed regardless of the route of administration. The solubility of an API, therefore, plays a crucial role in bioavailability given that drug absorption is a function of solubility and permeability. There are various techniques to enhance the drug solubility such as particle size reduction, use of surfactants, salt formation, nano-suspension, solid dispersion, etc. The solid dispersion is an important approach for improvement of bioavailability of poor water-soluble drugs.