Pellet (or bead) technology allows a variety of different drug delivery profiles to be achieved by coating drug and excipient with various polymers. The drug cores are generally spheroidal in shape and have a diameter in the range of 300-1,700 μm. Two types of process are used to generate the spheroidal pblog. The first of these processes, which allows potencies up to 90%, utilizes extrusion and spher’oidisation to form a drug core with a polymer coat.
The second process is known as drug layering by Wurster and drug layering by a drug layering system, where the drug pblog are fixed to the outside of a seed core (typically a sugar sphere). This process provides a very tight size distribution of pellets. Drug potencies up to 60% are possible. For both of the processes above, the desired drug release profile is achieved by coating pblog with the appropriate polymer.