ABSTRACT
Controlled release may be defined as a technique or approach by which active chemicals are made available to a specified target at a rate and duration designed to accomplish an intended effect. More specifically, an oral controlled release drug delivery system is, in principle, a de vice or dosage form that controls drug release into the absorption site in the gastrointestinal (GI) tract. It controls the drug absorption rate to achieve the desired plasma profiles defined by the steady-state pharmacology (1). A typical controlled release system is designed to provide constant or nearly constant drug levels in plasma with reduced fluctuation via slow release of drug over an extended period of time. Controlled release systems are sometimes called ex tended release or sustained release systems. In practical terms, an oral controlled release should allow a reduction in dosing frequency as compared to that drug presented as a conventional dosage form (2 ).
