[Bioavailability of penicillin V in aqueous dosage forms].
The bioavailability of Megacillin-oral-Trockensaft (active substance: potassium salt of phenoxymethylpenicillin, penicillin V potassium) was compared with that of another commercially available drug containing the same active substance. In a cross-over study, 12 healthy volunteers were administered by oral route 10 ml of each preparation (equivalent to 600 000 U = 392.2 mg potassium salt of phenoxymethylpenicillin) under standardized experimental procedure. Relative bioavailability was assessed by determination of phenoxymethylpenicillin concentrations in the plasma, employing both microbiological assay as well as high-performance liquid chromatography, by computation of the areas under the plasma concentration curves, and by calculation of the time periods necessary for the attainment of maximum plasma concentrations. In order to assess differences between the two forms in duration of efficacy, calculation of time intervals were based on plasma concentrations which were above 0.5; 1.0 or 1.5 micrograms/ml, respectively. Results of this comparative study indicate that Megacillin-oral-Trockensaft is superior to the other commercial preparation. The considerably better bioavailability of Megacillin-oral-Trockensaft is attributed to a substantially higher absorption rate and to a 2.4 times greater extent of absorption. Due to the distinct advantage in the bioavailability of Megacillin-oral-Trockensaft peak plasma concentrations of phenoxymethylpenicillin 5-6 fold higher and are reached faster when compared with those following intake of the other form tested. In practice, the superior bioavailability of Megacillin-oral-Trockensaft guarantees quicker initiation of therapeutic activity and greater safety (higher plasma concentrations, prolonged effect).