ABSTRACT
The aim of the present study was to assess the coating of drug-loaded sugar beads and lactose granules with Compritol 888 (National Formulary (NF)--Glyceryl Behenate). Theophylline was used as tracer and layered onto the beads, or granulated with lactose and sugar. Coating conditions (temperature, spray-rate, air pressure, etc.) were investigated for the production of prolonged release beads or granules, and dissolution kinetic curves were discussed. The study confirms the satisfactory coating potential of the hot-melt fluid-bed coating process on large spherules or granules. The optimized conditions confirm previous work, underscoring the considerable importance of the temperature of molten coating materials and the atomization air pressures. More sophisticated equipment would undoubtedly produce more efficient coating but the technique nevertheless seems promising. Practical data is now available for standard top spray equipment for fine and coarse granules. (1) Granule and spherule surface adhesion is controlled and consistent; (2) the coating is homogeneous, with continuous atomization and spraying onto the support; and (3) the release profile is directly related to the quantity of wax applied. Several competing mechanisms are also involved, including a diffusion-controlled process and a dissolution mechanism. Dissolution profiles appear to be consistent from one batch to another.
