Verapamil

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Abstract
Verapamil may have application in the field of obstetrics for treatment of maternal and fetal tachyarrhythmias. The maternal and fetal hemodynamic effects of this drug were assessed and its placental transfer and effects on maternal and fetal atrioventricular conduction in the pregnant ewe were determined. Verapamil, 0.2 mg/kg, administered i.v. over 3 min, resulted in a transient decrease in maternal mean and diastolic blood pressures. There was no significant change in fetal systolic, diastolic and mean blood pressures. Maternal and fetal heart rates also were unchanged throughout the experiment. Atrioventricular conduction, assessed by measurement of PR intervals, was prolonged in both the ewe (41%) and the fetus (78%). Placental transfer of verapamil was limited, as shown by the umbilical vein to uterine artery drug concentration ratios of 0.35-0.45 throughout most of the experiment. Fetal hepatic extraction of the drug appeared to be substantial, since the drug concentration in the fetal carotid artery was less than that of the umbilical vein at 1, 3 and 5 min after drug injection.