Abstract: Pharmaceutical compositions of the prodrug type, a process for the preparation thereof, a process for the preparation of the as prodrug functioning compounds and compounds obtained herein.The pharmaceutical compositions of the invention contain organic acid anhydrides with formula 1 through 5, as well as the pharmacological acceptable salts thereof as prodrug functioning compounds, together with a suitable pharmaceutically acceptable gaseous, liquid or solid carrier.The prodrug systems of the invention possess as favorable property that they amend the residence time of the pharmaceutical composition in the body by influencing the transport system.Furthermore they increase the biological availability because of the more lipophilic properties of the anhydride compared with the acid, so that this improved administration performance may contribute to lower dosages.