[Pharmacokinetic investigations of verapamil used as a concomitant drug in treatment of premature labor].

The study carried out on 35 pregnant women, who were threatened with fenoterol and verapamil by premature delivery. The pharmacokinetics of verapamil have been examined after single dose and in steady state using drug in a dose of 2 x 80 mg/day (15 women) and 3 x 40 mg/day (8 women). Verapamil in a dose of 2 x 80 mg/day induced average steady state concentration in range of 40.6 +/- 7.8 ng/ml to 134.2 +/- 56.9 ng/ml and in a dose of 3 x 40 mg/day 28.9 +/- 5.1 ng/ml to 69.8 +/- 11.2 ng/ml. Since most authors take as optimal therapeutic level of verapamil in blood the range of 100-200 ng/ml, it seems that dosage regimen of 2 x 80 mg/day can be recommended. Additionally, verapamil concentration in maternal blood and in amniotic fluid were determined simultaneously in a group of 12 pregnant women. Verapamil readily penetrates placenta reaching in amniotic fluid about 70% of the concentration observed in maternal blood.