The occurrence of pharmaceuticals in aquatic environments originating from human consumption has received increased scientific attention during the last decades due to concerns regarding their combined environmental effects. This concerns stress the need of studies quantifying dissipation rates of pharmaceutical in aquatic ecosystems. The aims of this study were: i) to assess the degradation rates of trimethoprim (TPR), diphenhydramine (DPH), diclofenac (DCL), oxazepam (OXZ) and hydroxyzine (HDZ) in laboratory incubations, and ii) to compare laboratory assessment of dissipation rates with previously measured in situ half-lives of these drugs in a pond ecosystem. I hypothesized that the dissipation of these five drugs dissolved, in laboratory incubations, is affected by common environmental parameters such as temperature, UV-light, organic solutes and presences of sediments. In line with my hypothesis, all substances were affected by my treatments. Here, main parameters affecting the dissipation of the drugs were UV light and to a lesser temperature (i.e. through microbial degradation). All drugs were found to be affected by sediment sorption, especially HDZ where 95 % of the applied pharmaceutical was adsorbed. Laboratory estimate with highest environmental relevance (low TOC and 3 °C water temperature or low TOC, sediments and UV light) seemed to predict field estimates fairly well for all of the drugs beside OXZ and DCL. Given the strong adsorption for sediments seen in the laboratory incubations, it seems likely that the mismatch between laboratory inferred half-lives and the in situ half-lives for OXZ was likely caused by sediment exchange processes releasing drugs initially adsorbed to the sediments into water column over time.