Solubility and Dissolution Enhancement : Technologies and Research Emerged

INTRODUCTION Solubility is defined in quantitative terms as the concentration of solute in a saturated solution at a certain temperature and pressure. Qualitatively it is defined as the spontaneous interaction of two or more substances to form a homogenous molecular dispersion. The United State Pharmacopoeia (USP) and national formulary lists the solubility of drug as the number of milliliters of solvent in which 1 g of solute will dissolve. The Indian pharmacopoeia define the term very soluble, freely soluble, soluble, sparingly soluble, slightly soluble, very slightly soluble and practically insoluble as mentioned in Table 1. Therapeutic effectiveness of a drug depends upon the bioavailability and ultimately upon the solubility of drugs molecules. Solubility is an important parameter to achieve desired concentration of drug in systemic circulation for pharmacological response. Dissolution is defined as the process by which solid substance enters in solvent to yield a solution. The solubility of the drug play prime role in controlling its dissolution from the dosage form. Dissolution of solid dosage forms depends upon the solubility of the drug substance in the surrounding medium. Dissolution is the process in which a solid substance gets dissolve in a given solvent i.e. mass transfer from the solid surface to the liquid phase. A polar solute will dissolve to a greater extent in a polar solvent.