Biphasic Oral Solid Drug Delivery System: a Review

The manufacture of bi-layer tablets, produced by the sequential compaction of loose powder layers has recently become of increased interest within the pharmaceutical industry due to the tailored release profiles of active ingredients that may be obtained. In a bi-layer configuration, the immediate release layer of the bilayer tablet has worked as the loading dose and the sustained release layer has maintained the therapeutic plasma drug concentration for prolonged time. Several pharmaceutical companies are currently developing bi-layer tablets, for a variety of reasons: patent extension, therapeutic, marketing to name a few. To reduce capital investment, quite often existing but modified tablet presses are used to develop and produce such tablets. This article explains why the development and production of quality bilayer tablets needs to be carried out on purpose-built tablet presses to overcome common bi-layer problems, such as layerseparation, insufficient hardness, inaccurate individual layer weight control, cross-contamination between the layers, reduced yield, etc. Using a modified tablet press may therefore not be your best approach in producing a quality bi-layer tablet under GMPconditions, especially when high production output is required.