Tablet Processing

Tablets are made by compaction of powder that has been filled volumetrically into a die. Reproducible die fill is therefore an essential element of successful tablet making.

Free flowing powders suitable for die filling are made by one of three methods, namely Wet Granulation, Dry Granulation and Direct Compression.

Direct Compression is the simplest process requiring the fewest process steps and the least equipment. Minimally weighing, blending, sieving and tablet machines are needed. A Direct Compression filler-binder has been processed by the excipient supplier to impart good flow and good compactability to the formulation.

Wet Granulation requires (expensive) equipment for Wet Granulation (e.g. high shear-mixer granulator) and drying (e.g. fluid bed drier) and a mill to reduce the dried granules to the desired particle size.

A process that may be thought of as intermediate between Wet Granulation and Direct Compression is Dry Granulation. In Dry Granulation a blend of the API and excipients is first compacted (densified) using a roller compactor (roller compaction) or a large tablet machine (slugging), the compacts so formed are milled into granules which are then lubricated and tableted. Dry Granulation therefore processes the API with the excipients and typically improves the flow of the compression mix.