Critical variables affecting the layering method of pelletization

The oral route of delivery is the most preferred route for administering most of the drugs. Pellets have gained importance since they offer numerous advantages like decreased dose dumping, improved patient compliance since dosing frequency is reduced, and ease of administering multiple chemically incompatible drugs immediately without the possibility of them interacting with each other. The critical variables related to process and equipment are identified and what impact they have on the quality of pellets formed is discussed. The position of the spray nozzle also affects the pellets and their yield. A complete guideline has been drawn which makes the process of pelletization using the Wurster method easier. The process variables affecting the pelletization process include inlet and product temperature, relative humidity, batch size; spray rate, and atomization air pressure and the equipment variables include column height, air distribution plate, a type of filter, and shaking interval. All these variables have a low, medium, or high impact on the process and they all together contribute to the quality of pellets formed. This review article focuses on critical process and equipment variables affecting the process of pelletization and the quality of pellets formed when using the Wurster equipment. The main objective is to review critical variables affecting the layering method of palletization and to sketch some basic problems encountered during pelletization and their troubleshooting.