Impact of Capsules as a Carrier for Multiple Unit Drug Delivery and the Importance of HPMC Capsules

The word ‘capsule’ is derived from the latin capsula, meaning a small box. It is a solid oral dosage form in which the active ingredients and diluents are contained in a two-piece hard shell, usually made of gelatin. In the development of new medicines, there are several problems to be solved. The formulation, and its important stability and releasecharacteristics, control and reproducibility of the production process are other factors to be taken into account and, increasingly, research costs and development timeframes have also to be considered. When it comes to a decision at the end of phase II, which dosage form will be developed for the market, high production costs of hard gelatin capsule products are generally assumed. Multiple unit dosage forms are mainly oral dosage forms consisting of a multiplicity of small discrete units, each exhibiting some desired characteristics. It is even possible to include a number of dosage forms – such as tablets, pellets, capsules, powders and granules – within a single formulation. In this way, incompatibilities and interaction between the different drug substances in combination products can be prevented. Hard gelatin capsules are particularly suitable for their development and manufacture. Hard gelatin capsules do have some drawbacks. To overcome these problems, pharmaceutical scientists have developed capsules made of starch, cellulose derivatives and polyvinyl alcohol copolymer. To date, HPMC capsules have been successfully utilized for pharmaceutical products.