An Evaluation of Tricalcium Phosphate Excipients Particularly Using Instrumented Rotary and Single Station Tablet Presses

Abstract

Two direct compression grades of tricalcium phosphate, Tri-Compress^R (Edward Mendell Co., Inc.) and Tri-Tab^R (Stauffer Chemical Co.), and a product containing tricalcium phosphate, D locust bean gum and citric acid, Loco-Tab^R (Ingredient Technology Corp.), were studied. Loco-Tab is composed of smaller particles having more irregularly shaped surfaces than the others. It is also less dense and somewhat less flowable than the other materials. None of these excipients lost weight at elevated temperature and none can be considered to be hygroscopic. Compressibility in formulations was studied using instrumented rotary and single station tablet presses. In all cases, the single station press yielded harder tablets at a given compression force. Dissolution of an insoluble drug was affected to a degree by the press used. Drug dissolution from Loco-Tab formulations was excellent at all tablet hardnesses, a highly desirable property for tablets to be coated using fluidized bed equipment. Loco-Tab would seem to be the calcium phosphate excipient of choice while recognizing that it is not a single entity and that it is acidic, in contrast to the neutral to slightly basic pH of the others.