Controlled release

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.

The science of controlled release originates from the development of oral sustained-release products in the late 1940s and early 1950s, the development of controlled release of marine anti-foulants in the 1950s and controlled release fertilizer in the 1970s where sustained and controlled delivery of nutrients following a single application to the soil. Delivery is usually effected by dissolution, degradation or disintegration of an excipient in which the active compound is formulated. Enteric coating and other encapsulation technologies can further modify release profiles.

In addition to pills, capsules and injectable drug carriers (that often have an additional release function), forms of controlled release medicines include gels, implants and devices (e.g. the Vaginal ring and contraceptive implant) and transdermal patches.

Examples of stimuli that may be used to bring about release include pH, enzymes, light, magnetic fields, temperature, ultrasonics, osmosis and more recently electronic control of MEMS and NEMS.

Examples of cosmetics, personal care and food science applications often centre on odour or flavour release.

The release technology scientific and industrial community is represented by the Controlled Release Society (CRS). The CRS is the worldwide society for delivery science and technologies. CRS serves more than 1,600 members from more than 50 countries. Two-thirds of CRS membership is represented by industry and one-third represents academia and government. CRS is affiliated with the Journal of Controlled Release and Drug Delivery and Translational Research scientific journals.