Human pharmacokinetics of cadralazine: a new vasodilator

The pharmacokinetic profiles in plasma and the renal elimination of 2-(3-[6-(2-hydroxypropyl)ethylamino]pyridazinyl)ethylcarbazate+ ++ were investigated in six healthy volunteers following single oral doses of 5, 10 and 20 mg of cadralazine. The study was run in a randomized change-over design experiment. Concentrations of cadralazine in plasma and urine were determined by a high-performance liquid chromatography method. Maximum plasma levels (Cmax) were reached between 0.25 and 1.0 h (tmax) after administration and ranged from 69.8 to 210.0 ng/g after the 5 mg dose, 148.9 to 333.3 ng/g after the 10 mg dose and 292.9 to 474.5 ng/g after the 20 mg dose. The corresponding area under the plasma concentration-time curve (AUC24hO) are 330, 621 and 1168 (ng/g). h. Mean renal elimination of the unchanged-drug ranged from 69 to 73% of the dose. Mean Cmax, AUC24hO and mean total renal elimination were linearly dose-related. An elimination half-life from plasma of about 2.5 h was observed for cadralazine. Estimations for the mean renal and total clearance range from 185 to 216 ml/min and 251 to 295 ml/min, respectively.