[Pellets preparation by the drug layering technique in a rotary processor]

Pelletization by the layering technique can be carried out by applying a liquid (a drug solution or suspension) or a drug powder using either coating drums or a fluidized bed equipment. This technique is used particularly for the formulation of multiparticulate controlled release dosage forms. Application of a drug on inactive beads in a centrifugal fluid-bed equipment (a rotary processor) represents the up-to-date technique of pellets production. Pelletization by the tangential drug-layering process is a multivariate process, and it is important to identify as well as to control the process variables and conditions. The goal of this paper is to give a summary about one of the newest pelletizing technologies - drug layering in a rotary processor, to outline its possibilities, and particularly to describe the influence of formulation and process parameters on the properties of the final product.