Pharmaceutical Technology-12-01-2005

Almost all pharmaceutical manufacturing processes require handling and processing cohesive powders. The application of sufficient shear (i.e., the total deformation that the bulk of granular material undergoes under applied shear stress) is an essential factor in such processes. Sufficient shear is required to mill and de-lump materials, achieve sufficient flow, and homogenize cohesive ingredients. Shear mixing plays a critical role in the blending of dry powders, particularly for those that contain a minor cohesive component such as a solid lubricant or a drug. This mechanism is necessary to achieve a satisfactory homogeneity and disintegrate possible agglomerates. Excessive shear can be disadvantageous, however, and can lead to electrostatic buildup, attrition, and overlubrication.

All pharmaceutical products are formulated to specific dosage forms for drugs to be effectively delivered to patients. Typical pharmaceutical dosage forms include oral tablets, capsules, solutions, suspensions, topical ointments, gels, and solutions, and injections for intravenous (IV), intramuscular (IM), or subcutaneous (SC) administration. In addition, various drug delivery systems have been developed for transdermal, intranasal, and pulmonary deliveries. Different dosage forms require different pharmaceutical technologies and usually present different technical challenges for formulation development.

The pharmaceutical industry handles large volumes of granular materials such as powder blends for tablet production and filled capsules everyday (1, 2). Slight changes in ingredient properties or process operation conditions can have a major effect on a finished product's quality. Given the market and regulatory uncertainties that are commonly associated with drug product development, pharmaceutical companies typically have several drugs in various developmental stages at the same time. Because of this volume, the industry must have computer-based rapid-prototyping tools that can efficiently capture and resolve the technical aspects of drug product development so that companies can confidently make decisions about drug portfolio management and planning (3, 4).

Solid oral drug products are one of the oldest of all manufactured dosage forms (1). Today, the development of an appropriate formulation of drug and excipients and of an effective manufacturing process to create a tablet or capsule is slowly transforming from a practice of applied art to one of applied science. The US Food and Drug Administration supports this change by expecting sponsors of new drug applications to understand, describe, and control materials and processes as well as the risks associated with drug product manufacturing (2). These steps will ensure the consistent production of products that meet their specifications and remain safe and effective during their shelf life.