Pellets as Controlled Release Drug Delivery System: A Review

In the recent years, considerable attention has been focused in the development of controlled release drug delivery system. The pellets have since long been used as an important formulation tool. Pelletization is an agglomeration process that converts fine powders or granules of bulk drugs and excipients into small , free flowing , spherical or semispherical units referred to as pellets. Pellets range in size typically, between 500- 1500 μm. When pellet containing the active ingredient are administered in vivo in the form of suspension capsule or disintegrating tablets, they offer significant therapeutic advantage over single unit dosage forms. An ideal controlled drug delivery system is the one which delivers the drug at a predetermined rate, locally, or systemically, for a specified period of time. Controlled release pellet formulation can be formulated by many techniques such as extrusion/spheronization, powder layering, solution/suspension layering etc.

Various applications of pellets in controlled drug delivery system formulation, recent developments, polymer and excipients used for formulation of controlled release drug delivery system are discussed in this review.