The following are the most important topics to be covered: kinetics of drug release and physical parameters that affect them; constructional changes in well-established dosage forms; solid dispersion systems; osmotic devices; membrane-controlled drug delivery, as for example in transdermal administration; nanoparticles; microcapsules; liposomes; insoluble plastic matrices; soluble and bioerodable polymers; implants; aerosols; drug targeting using monoclonal antibodies; self-regulating drug delivery; prodrugs. Each dosage form will be placed in its scientific, practical, and historical perspective; the governing release mechanisms and its advantages and limitations will be discussed.