Solid-state properties of powders in the formulation and processing of solid dosage forms

Abstract

Powdered drugs are not generally used alone when formulating solid dosage forms. A variety of excipients. such as diluents, disintegrants, binding agents and lubricants, the vast majority in powder form. are included for particular functions. These are then processed into convenient forms for drug administration. Whilst full chemical profiles of drugs and additives are generally well defined fCor quality assurance purposes, it is also relevant to understand their fundamental powder and processing properties since these parameters can significantly affect the manufacture and performance of solid dosage forms. In addition, with the increasing sophistication of processing equipment with regard to speed and automation and the complexity of certain f,lrmulations, such as controlled release preparations, the selection of drug species and additives has become more critical. Subtle variations in solid-state properties, here regarded as the intrinsic properties of component crystals, between butches and between suppliers, can lead to manufacturing problems (Jones, 198 I). Increased understanding of powder properties now allows powder characteristics to be defined more fully permitting a more quantitative approach to formulation design und processing than by the more traditional empirical methods. In this article, the significance of the solid-state properties of pharmaceutical powders is considered in terms of the selection of drug species and additives in formulations, and the processes involved in the manufacture of solid dosage forms.