Effect of phytomedicines, AM-1, niprisan and nifadin on the pharmacokinetics of chloroquine in rats.

The single oral dose pharmacokinetics of chloroquine was studied alone and after coadministration with phytomedicines NIPRID\92\001\1-1 (AM-1), Niprisan, and Nifadin in rats. Plasma chloroquine concentrations were measured using High performance liquid chromatography (HPLC) 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 chloroquine produced decrease in the serum concentration of chloroquine at each sampling time. The highest decrease of 85% occurring at the time of peak concentration (1 h) was recorded with Nifadin, followed by 75% with Niprisan the least was 50% with AM-1. Significant reduction was also observed in some other parameters, such as area under the serum concentration- time curve (AUC(0-24)) and maximum serum concentration (Cmax) while the apparent volume of distribution (Vd) and elimination half-life (t 1/2beta) increased significantly (P< 0.05). It was concluded that the gastric presence of the herbal medicines significantly impaired the absorption of chloroquine in rats.