In Vivo and In Vitro Effects of Kalmegh (Andrographis paniculata) Extract and Andrographolide on Hapatic Microsomal Drug Metabolizing Enzymes¹

Abstract

Administration of single doses of kalmegh leaf extract (KE; 0.5 mg/kg and 1.0 g/kg, p.o.) and andrographolide (A; 5.0 mg/kg and 10.0 mg/kg, p.o.) to adult male albino rats (125-150 g b. wt.), both at higher and lower doses characteristically inhibit hepatic microsomal anilinehydroxylase, N-demethylase, and O-demethylase after varying times (4-12 h) of treatment and a kinetic study indicates the nature of inhibition to be non-competitive. Repeated administration of these experimental drugs for 7-30 consecutive days, on the other hand, produces induction of all these enzymes and this type of induction is accompanied by the increase in V_max but not any appreciable change in their K_m value.