Effects of Eudragit (R) and ethylcellulose coatings

In this short review the fundamental differences between pH- and diffusion controlled drug releases are outlined. In a following step the characterist ics of single unit- and multiple units-dosage forms are discussed, and the predominantly used excipients for pH- and diffusion-controlled drug release are mentioned. Finally rhp influences of such special galenical designs fo r controlled drug release are explained in the light of some selected examp les. The exact knowledge and consideration of these facts are extremely importan t in the development of optimal drug systems, in the interpretation of resu lts, and with respect to interdisciplinary cooperation, e.g. between pharma ceutical technologists and pharmacologists.