The means by which a drug is introduced into the body is almost as important as the drug itself. It is imperative that drug concentration in the blood be maintained at a level that provides maximum therapeutic benefit for all day formulations. This is a function of dissolution rate and formulation system. Controlled release delivery systems fall into these categories: transdermal, intravenous, and oral. This type of system is a focus for regulatory agencies in determining how best to assure drug quality and performance. Dissolution testing for controlled release formulations is the subject of this research.