[Comparison of blood levels, excretion and metabolite pattern in rats non-pretreated and pretreated with subacute doses of AR-L 115 BS].

Following p.o. administration of 50 mg/kg 2-[(2-methoxy-4-methylsulfinyl)phenyl]-1H-imidazo[4,5-b]pyridine (AR-L 115 BS) labelled with 14C the pharmacokinetics and metabolic pattern were studied in rats. The animals were divided into two groups: one group was non-pretreated and the other group was pretreated with non-radioactive AR-L 115 BS during a subacute toxicity test for 3 months. In all measurements statistically significant differences were detected. In pretreated rats blood levels and urine excretion balance were lower than in the control animals. In contrast to these findings a faster and higher faecal excretion was found in the pretreated animals. The metabolic pattern of plasma and urine shows a higher degree of metabolism in pretreated animals than in control animals. It is therefore concluded that the differences observed are caused by induction of the drug metabolizing enzyme systems.