Comparison of plasma and skin blister fluid concentrations of two orally administered nitroimidazoles

Abstract

Plasma and cantharidin-induced skin blister fluid concentration vs time curves for two nitroimidazoles, metronidazole and tinidazole, following a single oral 2.0 g dose of each drug administered separately were determined. The maximum metronidazole and tinidazole concentrations in plasma were similar (about 36 mg/l) and were achieved after 1 and 2 h, respectively, whereas in blister fluid, the maximum tinidazole concentration was slightly higher (29 vs 23 mg/l), but they were both observed after about 6 h. The areas under the concentration vs time curve of the fluids examined for tinidazole were about twice those for metronidazole. The half-life of tinidazole was twice that of metronidazole. The ratio of the area under the curve for blister fluid to that for plasma proved that the drugs penetrated to a very high degree from the blood stream into the blister fluid, and therefore into inflamed areas.