Pharmacokinetics of tiropramide after single doses in man

The plasma levels and urinary excretions of (+/-) alpha-(benzoylamino)-4-[2-(diethylamino)ethoxy]-N, N-dipropyl-benzenepropanamide (tiropramide) and of some of its metabolites were studied in healthy volunteers after the following single-dose administrations of tiropramide hydrochloride: a) i.v. 50 mg, oral 100 mg or rectal 200 mg; b) i.v. 50 mg or i.m. 50 mg; c) oral 100, 200 or 400 mg. After i.v. bolus the plasma levels of tiropramide are consistent with a three-compartment open pharmacokinetic model. The steady-state volume of distribution is 221 l. The terminal elimination constant is 0.279 h-1 (t1/2 = 2.5 h). After i.m. injection the plasma levels increase rapidly (invasion t1/2 = 2 min) and then are similar to those found after i.v. bolus. After oral administration appreciable plasma levels are found after lag times of 18-27 min. They increase with an invasion t1/2 of 14-22 min. The peak is reached 1-1.7 h after administration and the elimination occurs with a constant of 0.20-0.23 h-1. After rectal administration appreciable plasma levels are found after a lag time of 11 min and increase with an invasion t1/2 of 6 min. The peak is reached at 2.2 h. The elimination constant is 0.21 h-1. Tiropramide and some of its metabolites can be determined in the urine by gas-liquid chromatography. The following percentages of the administered dose of tiropramide and tiropramide-related substances can be found in the 24-h urines. After i.v. bolus: 16.2; after i.m. injection: 17.0; after oral administration: 19.6; after rectal administration 13.1.(ABSTRACT TRUNCATED AT 250 WORDS)