Controlled release is a term referring to the presentation or delivery of compounds in response to stimuli or time. This can be for purposes in several areas including agriculture, cosmetics and personal care, pharmaceuticals and food science. Most commonly it refers to time dependent release in oral dose formulations. Timed release has several distinct variants such as sustained release where prolonged release is intended, pulse release, delayed release (e.g. to target different regions of the GI tract) etc. A distinction of controlled release is that not only prolongs action but it attempts to maintain drug levels within the therapeutic window to avoid potentially hazardous peaks in drug concentration following ingestion or injection and to maximize therapeutic efficiency.