Preparation of Oral Penicillin G Procaine Suspensions of Extended Shelf Life

Penicillin G procaine solutions were prepared in an aqueous vehicle in which penicillin solubility was very low. Rates of penicillin degradation in this vehicle were determined at various temperatures. Penicillin G procaine suspensions were prepared in the same vehicle, and were assayed at time intervals under various temperature storage conditions. Penicillin activity of the suspensions was shown to be related to the concentration of the drug in suspension ana to penicillin solubility in the vehicle at the storage temperature. Calculated penicillin activities showed fair correspondence with experimentally determined values. The use of chemical kinetics in predicting shelf life of pharmaceuticals is illustrated.