Controlled release (CR) has been a subject of continued interest, and the pharma industry is taking a closer look into release profiles of drugs because of risk factors associated with early release (dose dumping) before being delivered to intended sites to achieve the desired efficacy, and to overcome toxicity and drug abuse issues. The latter has become more challenging, especially in controlled delivery of opioids in pain management. Nonetheless, the former one is also poorly understood because of complexity associated with the mechanism of controlled release from a particular dosage.

In spite of those challenges, the industry is aiming to design CR formulations that will help maintain an optimal drug concentration in systematic circulation between minimum toxic concentration (MTC) and minimum effective concentration (MEC), thus alleviating the side effects of dosages. There are various approved controlled release drugs, and those include Anpec® SR; Cordilox® SR; Imdur Durules, Isoptin® SR; Monodur Durules®; Nuelin® SR; Sinemet® CR; Theo-Dur®; Adalat® OROS; Adalat® tablets, Agon SR; Ceclor® CD; Felodur ER; Keflor® CD; Kinidin Durules®; MS Contin®; Naprosyn® SR; Plendil® ER; Tenuate Dospan® among others.