The influence of Nifadin, Niprisan and Niprd/92/001/1-1 (AM-1) on the pharmacokinetics of metronidazole in rats.

The single oral dose pharmacokinetics of metronidazole was studied alone and after co-administration with phytomedicines, Nifadin, Niprisan and Niprd/92/001/1-1 (AM-1), in rats. Plasma metronidazole concentrations were measured using high-performance liquid chromatography method developed earlier in our laboratory. The data were fitted into a WinNonlin standard non-compartmental programme. The co-administration of the herbal medicines with metronidazole produced an increase in the serum concentration of metronidazole at each sampling time. The highest increase of 184% occurring at the time of peak concentration (1 h) was obtained with AM-1, followed by 145% with Niprisan, the least was 131% with Nifadin. Significant increase was also observed in some other parameters, such as area under the serum concentration-time curve (AUC0-24) and maximum serum concentration (Cmax), while the apparent volume of distribution (Vd) and plasma clearance (C1) reduced significantly (P < 0.05). It was concluded that the gastric presence of the herbal medicines impaired the absorption and elimination Niadin alone) of metronidazole in rats significantly (P < 0.05).