Arsenite-induced drug-drug interactions in rats

Arsenite is an important heavy metal. Some Chinese traditional medicines contain significant amounts of arsenite. The aim of this study was to investigate subacute exposure of arsenite on activities of cytochrome P450 enzymes and pharmacokinetic behaviors of drugs in rats. Midazolam, tolbutamide, metoprolol, omeprazole, caffeine, and chlorzoxazone, the probe substrates for CYPs3A2, 2C6, 2D2, 2C11, 1A2, and 2E1, were selected as model drugs for the pharmacokinetic study. Significant decreases in AUCs of probe substrates were observed in rats after consecutive 30 day exposure toAs at 12 mg/kg. Microsomal incubation study showed that the subacute exposure to arsenite resulted in little changes in effects on the activities of P450 enzymes examined. However, everted gut sac study demonstrated that such exposure induced significant decreases in intestinal absorption of these drugs by both passive diffusion and carrier-mediated transport. In addition, in vivo study showed that the arsenite exposure decreased the rate of peristaltic propulsion. The decreases in intestinal permeability of the probe drugs and peristaltic propulsion rate most likely resulted in the observed decreases in the internal exposure of the probe drugs. Exposure to arsenite may lead to the reduction of the efficiencies of pharmaceutical agents co-administered resulting from the observed drug-drug interactions. Significance Statement Exposure to arsenite may lead to the reduction of the efficiencies of pharmaceutical agents co-administered resulting from the observed drug-drug interactions. In this study, we found that P450 enzyme probe drug exposure was reduced in arsenic-exposed animals (AUCs) and the intestinal absorption of the drug was reduced in the animals. Subacute arsenic exposure tends to cause damage to intestinal function, which leads to reduced drug absorption.