The fundamentals of sustained release formulation design and its various varieties are covered in this article. For pharmaceutical technologists, creating oral sustained release matrix tablets with a consistent release rate has always been difficult. By optimizing the bio-pharmaceutics, pharmacokinetics, and pharmacodynamics properties of drugs in a way that minimizes dosing frequency to the point where a single daily dose is adequate for penetration, polymer swelling, drug dissolution, drug diffusion, and matrix erosion, oral sustained release (SR) products offer an advantage over traditional dosage forms. Sustained release matrix tablets have been developed for medications that are very soluble in water, such as ranitidine and diltiazem. Drug delivery systems that are intended to accomplish or prolong therapeutic effect by continuously releasing medication over an extended period of time following administration of a single dose are referred to as sustained release, prolonged release, modified release, extended release, or depot formulations. These dosage forms are appealing for a number of reasons: they increase the drug product's bioavailability, decrease the frequency of administration to extend the duration of effective blood levels, lessen peak trough concentration fluctuations and side effects, and potentially improve the drug's specific distribution.

Key words: polymers, controlled drug delivery, matrix system.