Simultaneous determination of the intravenous and oral pharmacokinetic parameters of D,L-verapamil using stable isotope-labelled verapamil.
Following i.v. administration, the plasma concentration-time curve of verapamil could best be described by either a mono- or biexponential equation. Total plasma clearance (1.26 1/min) approached liver blood flow (1.51/min), so it can be concluded that its clearance is liver blood flow-dependent. Although absorption was almost complete after oral administration, absolute bioavailability (20%) was low, due to extensive hepatic first-pass metabolism. The approach using stable isotope-labelled and unlabelled drug permits simultaneous administration by the intravascular and extravascular routes, thus allowing determination of absolute bioavailability in a single experiment.
D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D003903:Deuterium; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D014700:Verapamil / Q000008:administration & dosage / Q000378:metabolism*
D003903:Deuterium; D014700:Verapamil