[Effect of euddragit and ethylcellulose coatings. A short review of pH and diffusion controlled drug delivery]

In this short review the fundamental differences between pH- and diffusion-controlled drug releases are outlined. In a following step the characteristics 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 the influences of such special galenical designs for controlled drug release are explained in the light of some selected examples. The exact knowledge and consideration of these facts are extremely important in the development of optimal drug systems, in the interpretation of results, and with respect to interdisciplinary cooperation, e.g. between pharmaceutical technologists and pharmacologists.