Within the Center for Bio-Pharmaceutical Sciences the release characteristics of drugs form the major research object of the Division of Pharmaceutical Technology. Transdermal systems are being developed that can supply a drug during several days. Irritation of the skin may be avoided by using hydrogels. To enable long-term transdermal application also the colloidal structure of creams and ointments is investigated. As most drugs are to be taken orally, however, a research project was also started to make cheap and easy to produce controlled release tablets. The results with a microporous polypropylene polymer are promising.