In a cross-over study on twelve healthy volunteers cefpodoxime proxetil (CAS 87239-81-4) and acetylcysteine (CAS 616-91-1) were evaluated for possible pharmacokinetic interactions. After a standardized breakfast, the subjects received p.o. either 200 mg cefpodoxime administered as cefpodoxime proxetil (reference) or 200 mg cefpodoxime and 200 mg acetylcysteine (test). To determine the pharmacokinetic profile of cefpodoxime the plasma concentrations were determined by HPLC. The plasma concentration-time curve of cefpodoxime was very similar after both regimens, and with respect to cefpodoxime bioequivalence has been proven. The narrow range of 90% confidence intervals for the quotient test/reference for Cmax and AUC indicate reliable bioavailability of cefpodoxime proxetil independent of co-administered acetylcysteine.