On the pharmacokinetics and metabolism of propiverine in man

The pharmacokinetics of 14C-propiverine was studied in 13 volunteers and in 2 patients after a single i.v. injection of 5 mg or after oral administration of 15 mg. To each dose 1.11 MBq 14C-propiverine was added. The radioactivity measured in plasma, urine (and bile fluid), and the metabolites were estimated by an extraction procedure together with TLC and radiochromatography. Propiverine was eliminated from the plasma with a half-life time (t0.5) of 4.1 h (i.v. and per os), while the plasma radioactivity decreased with a t0.5 of 21.2 (i.v.) or 10.4 h (per os). Within 4 days, 84.5 (i.v.) or 53.5% (per os) of the administered radioactivity was excreted in urine. The absorption of radioactivity of propiverine amounted to 84.5%, while the amount of available propiverine was only 48.9%. In two patients with cannulated ductus choledochus, 21.5 or 14.7% of the administered radioactivity was excreted within 2 days. The metabolic pattern of plasma, urine and bile fluid mainly consisted of amine oxides, substances oxidized in the propyl side chain, desalkylated metabolites, substances with a N-demethylated piperidino group or with ester cleavage, and glucuronide conjugates. Unchanged propiverine appeared in plasma, urine and bile at about 6 to 8% of the administered dose.