Drug Release

Drug release from dosage forms (also termed drug liberation) is a prerequisite for absorption to occur: only free molecules in solution can cross biological barriers to reach systemic circulation. Depending on the characteristics of the drug delivery system, drug release may implicate a diversity of mechanisms, from diffusion to erosion, from partitioning to osmotic release. This chapters introduces the topic of drug release by presenting an overview of zero-order, first-order and “mixed” kinetics drug release. The simplest drug dissolution model (Noyes Whitney model) is also discussed.