Alteration of oral salivary pharmacokinetics of paracetamol by an investigational anti-malarial phytomedicine, in healthy human volunteers

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).

The effects of an investigational antimalarial agent, NIPRD-AM1 on the single dose pharmacokinetics of metronidazole in healthy human volunteers

The effect of concurrent administration of a novel phytomedicine, NIPRD-AM1 used for the treatment of malaria on the pharmacokinetics of metronidazole was investigated in healthy volunteers. The study was a completely randomized one, crossover involving administration of single dose metronidazole tablets (200 mg×2) concomitantly with NIPRD-AM1 capsules (250 mg×2) to 11 healthy volunteers. Blood samples were collected before and at pre-determined time intervals following administration of the drugs. Serum concentrations of the unchanged metronidazole were analyzed using a modified simple and sensitive reversed phase high performance liquid chromatography (HPLC) method. The method showed good precision for metronidazole with coefficient of variation less than 10%. The Pharmacokinetic parameters (AUC, Cmax, and Tmax) were generated using GraphPad Prism software version 2. The derived pharmacokinetic parameters (AUC, Cmax) following the administration of metronidazole alone and co-administration with NIPRD-AM1 were 76.12 μg/ml per hour, 7.94 μg/ml and 73.52 μg/ml per hour, 7.83 μg/ml, respectively. This differences were not statistically significant (P<0.05) and the relative bioavailability was found to be about 96%. The comparable relative bioavailabilty value obtained shows that there is little or no interaction between NIPRD-AM1 and metronidazole. The findings, therefore, showed that metronidazole can be administered with the phytomedicine NIPRD-AM1 without any significant effect on the pharmacokinetic profiles of metronidazole.