Chapter 8 - Pelletization

Abstract

Controlled release preparations can be administered orally in single or multiple unit dosage forms. Among multi-component dosage forms, the most commonly used dosage form is the pellet. It is an ideal dosage form, which on oral administration, disperses or disintegrates rapidly in the stomach to release drug particles, granules and spheroids. Pellets are agglomerates of fine powders or granules of bulk drugs and excipients. They consist of small, free-flowing, spherical or semi-spherical solid units, typically from about 0.5 to 1.5mm, and are intended usually for oral administration. Polymer-coated multi-particulates or Multiple Unit Pellet System have several therapeutic and technological advantages over single-unit dosage forms. Being small (<2mm), pellets or multi-particulates can distribute evenly in the gastrointestinal tract, resulting in fewer adverse effects. Pellets also reduce the risk of dose dumping compared to single-unit dosage forms, and result in a reproducible bioavailability. Pellets can be either filled into capsules or compressed into tablets as a dosage form to be administered. Pellets offer great flexibility in pharmaceutical solid dosage form design and development. They flow freely and pack easily without significant difficulties, resulting in uniform and reproducible fill weight of capsules and tablets. Processing conditions play a significant role in the development of good quality pellets, but the physical forces first bind the primary particles together and initiate the pelletization process. Physical forces determine the nature of the elementary growth mechanism that forms the basis of pellet formation in any processing equipment. There are numerous publications on the theory of formation of a pellet.