Review article: mechanisms of drug release from tablets and capsules. I: Disintegration.

Variable drug release from solid oral dosage forms has been an important cause of bioavailability problems in the past, and is a factor now carefully controlled in pharmaceutical products. In two reviews, we describe briefly the composition and manufacture of tablets and capsules, and the two main processes by which they release drugs; disintegration and dissolution. We will explain what is presently understood of the actual mechanisms of drug release and the physico-chemical factors that affect the release process. The strategies adopted by pharmaceutical scientists in designing modern oral solid dose forms to release drugs at reproducible and therapeutically optimal rates will be discussed. Finally, the role of gamma scintigraphy in assessing dosage form performance in vivo will be described.