ABSTRACT
Controlled drug delivery has emerged as a eld of study that concentrates to treat ailments with improved safety, efcacy, convenience, and patient compliance. Controlled release formulations release drugs at a constant rate for longer durations. The main principle behind the release of the drug is diffusion-mediated. Other mechanisms like swelling and erosion may also govern the release process. Controlled delivery formulations require lower quantity of the drug for achieving therapeutic activity for prolonged time. This reduces the toxicity associated with the frequent and higher dosing. These systems help improving the pharmacokinetic and pharmacodynamic proles of the drugs without compromising the therapeutic activity of the drugs. The controlled delivery formulations eliminate the potential of underdosing and overdosing and maintain the drug levels at the target sites within the therapeutic window. The less frequent dose requirement increases patient compliance.1 Along with the potential advantages, these dosage forms suffer from some drawbacks as compared to the immediate-release formulations. The major disadvantages include dose dumping and lack of precision in the controlled release mechanism leading to the variation in dosing.
