Urea belongs to frequently prescribed pharmaceuticals in topical dermatologic therapy of individually prepared medical preparations. However it is a quite unstable substance. For preparations containing urea it is necessary to choose appropriate pH and to avoid some incompatibilities. The proper galenic processing also depends on the urea concentration and the nature of vehicle base with which urea should be combi-ned. This páper aims to introduce urea characteristics, its basic use in dermatological practice, possibiliti-es of compounding with semi-solid vehicles most often ušed in combined prescriptions (Synderman, Cutilan, Ambiderman, Cremor neoaquasorb) according to prescribed urea concentrations, and to mention important incompatibilities and some mistakes in prescriptions.

        Key words: urea - urea stability - lactate buffer - inclusion into semi-solid vehicles - mistakes in pre¬scriptions