Accurate Bulk Density Measurement Maximizes Solid Dose Production

By Vinnie Hebert, Product Manager - Powder Flow Tester, Brookfield Engineering Laboratories, Inc

The most popular dosage form in the pharmaceutical industry is the compressed tablet. Fully two-thirds of all prescriptions are dispensed in a solid dosage form and half of these are compressed tablets. While it looks simple in its white or colored form, the compressed tablet is a complex mix of the active drug and a host of excipients. These excipients can be a combination of sweeteners, pigments, !ow aids, disintegrants, binders, etc. The reason tablets are the most common form of dosage is simple: It is the most cost-e"ective way of manufacturing solid form dosages in mass quantities. In commercial production, a tablet can be produced every 50 to 500 milliseconds. To ensure proper manufacturing at such rates, a key parameter of the powder formulation is its bulk density. If the bulk density of the formulation varies, this can cause a host of manufacturing problems. The bulk density of the formulation initially needs to be de#ned accurately.

Subsequent quality checks must be performed to ensure the bulk density metric of the formulation is within a speci#ed tolerance. Powder and Tablet Production There are two methods for producing powders: wet and dry granulation. Wet granulation uses a liquid binder to agglomerate the power mixture. This mixture is blended, dried and screened, then allowed to !ow into a die to form the tablet. A dry granulation is used when the formulation is more sensitive to heat and moisture. Both methods are de#ned by their bulk density in order to produce compressed tablets.