The pharmacokinetics of ameziniummetilsulfate in man. Single and repetitive oral administration of a therapeutically effective dose.

The pharmacokinetics of the antihypotensive drug 4-amino-6-methoxy-1-phenyl-pyridazinium methyl sulfate (ameziniummetilsulfate, LU 1631, Regulton), in the following briefly called amezinium, has been investigated in 8 healthy volunteers. Plasma concentrations were determined by means of a high pressure liquid chromatographic method after single oral administration of a therapeutic dose (10 mg), during repetitive dosing (10 mg b.i.d., 13 days) and following the last dose. The results demonstrate for amezinium rapid absorption (half-life about 0.6 h), good tissue penetration (distribution) with about 3.0 h half-life and comparably slow elimination (half-life about 12.0 h). Considering the results before and after multiple dosing and those of earlier studies (using higher dosages), none of the kinetic parameters showed any indication of dose dependency or changes by chronic dosing. These properties and the characteristics of amezinium with respect to absorption, bioavailability and elimination are considered favourable for safe and effective handling of the drug.