Inhibition of prostaglandin-induced uterine activity by nifedipine.

The effects of the calcium antagonist, nifedipine, on uterine activity induced by prostaglandins F2 alpha (PGF2 alpha) and E2 (PGE2) were studied in women undergoing therapeutic midtrimester abortion, and in patients with a missed abortion in the 16th to 27th week of pregnancy. In the five subjects receiving intra-amniotic PGF2 alpha (25 to 40 mg) for midtrimester abortion, nifedipine (30 mg orally) decreased uterine activity from a mean of 372 to 203 Montevideo Units. The effect on the intensity of the contractions was pronounced; frequently and basal tone were little affected. In patients with missed abortion, uterine contractions were induced by extra-amniotic application of PGE2 (0.5 to 1.5 mg) in a viscous gel. The activity was often more irregular than that in the women receiving intra-amniotic PGF2 alpha. However, nifedipine (30 mg orally) had a marked inhibitory effect on the uterine contractions. It is concluded that nifedipine can be used for treatment of uterine hyperactivity induced by prostaglandins. Combined treatment with beta 2-adrenoceptor stimulants might be considered.