Preparation and evaluation of combination tablet containing incompatible active ingredients.

Combination preparation plays an important role in clinical treatment because of its better and wider curative synergism and weaker side effects. However, the existence of incompatibility between active ingredients or between active ingredients and excipients presents a serious obstacle in the preparation of such combination solid dosage forms. In this study, aspirin and ranitidine hydrochloride, between which there existed a chemical interaction, were selected as model drugs. Aspirin powders without any additives were granulated with hydroxypropyl methyl cellulose (HPMC) water solution as a binder using a Wurster coating apparatus and the operation conditions were optimized by Artificial Neural Network (ANN) analysis. Under these conditions, the aspirin granules prepared showed good flowability and compressibility. On the other hand, ranitidine hydrochloride was coated with Aquacoat (ethyl cellulose aqueous dispersion) after preliminary granulation with the Wurster coating apparatus. The aspirin granules and coated ranitidine hydrochloride particles were compressed into tablets with suitable excipients. The combination tablets showed good dissolution, content uniformity and improved stability of active ingredients.