Pharmacokinetics and bioavailability of papaverine HCl after intravenous, intracorporeal and penis topical administration in beagle dogs.

Bioavailability and pharmacokinetics of papaverine HCl was studied in beagle dogs following intravenous injection, intracorporeal injection and topically applied gel on the penis. Also the effect of the sorption promoter Labrafil M-1944 CS on the permeation of papaverine from two gel formulations (PT and PTL) containing the co-solvent Transcutol was evaluated. Blood samples were analyzed by high performance liquid chromatography (HPLC). The pharmacokinetic parameters were determined using either curve-fitting (RE-SID) or compartment model independent method (AUC-RPP). The plasma concentration-time profiles show that papaverine HCl pharmacokinetics is best described by an open two-compartment model. The absolute bioavailability of papaverine HCl was determined to be 102.4%, 9.1%, and 12.4%, respectively, following intracorporeal injection, gel PT and gel PTL administration.