Drugs in Pregnancy and Lactation: Tenth Edition

ISRADIPINE

Calcium Channel Blocker

PREGNANCY RECOMMENDATION: Limited Human Data—Animal Data Suggest Low Risk

BREASTFEEDING RECOMMENDATION: No Human Data—Probably Compatible

PREGNANCY SUMMARY

Several studies have described the use of isradipine in pregnant women (18). No adverse fetal effects attributable to the drug were observed. Isradipine crosses the placenta to the fetus at term (3).

FETAL RISK SUMMARY

Isradipine is a calcium channel-blocking agent used in the treatment of hypertension. The drug is not teratogenic in rats or rabbits at doses 150 and 25 times the maximum recommended human dose, respectively. Embryotoxicity was not observed in either species at doses that were not maternally toxic (9).

In a study to determine the effects of isradipine on maternal and fetal hemodynamics, 27 women with pregnancy-induced hypertension in the 3rd trimester were treated with the drug, 2.5 mg twice daily for 4 days and then 5 mg twice daily (1). Hemodynamic measurements, conducted before and after 1 week of therapy, demonstrated a significant reduction in mean arterial pressure without a significant change in uteroplacental or fetal blood flows. The lack of change in uteroplacental blood flow suggested that there was uterine vasodilation with decreased uterine vascular resistance. No fetal adverse effects were observed (1).

A 1992 study examined the effect of isradipine on three standardized physical stress tests in 14 women under treatment for hypertension (3 with essential hypertension, 11 with preeclampsia) (2). Treatment with isradipine, 5 mg once daily for 4 days and then 5 mg twice daily, was begun at a mean 33 weeks’ gestation with delivery occurring at a mean of 38 weeks. The pregnancy outcomes were normal except for one newborn whose birth weight was below the 10th percentile and transient hyperbilirubinemia in two neonates (2).

A study reported in 1999 compared antihypertensive effect of isradipine (N = 20) with hydralazine and methyldopa (N = 19) in women with severe preeclampsia (8). There were no differences in the outcomes in terms of gestational age at birth, Apgar scores, and birth weight.

BREASTFEEDING SUMMARY

No reports describing the use of isradipine during human lactation have been located. The relatively low molecular weight (about 371), however, suggests that the drug is excreted into breast milk. The potential effects of this exposure on a nursing infant are unknown.

References

1.Lunell N-O, Garoff L, Grunewald C, Nisell H, Nylund L, Sarby B, Thornstrom S. Isradipine, a new calcium antagonist: effects on maternal and fetal hemodynamics. J Cardiovasc Pharmacol 1991;18(Suppl 3): S37–40.

2.Lunell NO, Grunewald C, Nisell H. Effect of isradipine on responses to standardized physical stress tests in hypertension of pregnancy. J Cardiovasc Pharmacol 1992;19(Suppl 3):S99–101.

3.Lunnell NO, Bondesson U, Grunewald C, Ingemarsson I, Nisell H, Wide-Swensson D. Transplacental passage of isradipine in the treatment of pregnancy-induced hypertension. Am J Hypertens 1993;6:110S–1S.

4.Wide-Swensson DH, Ingemarsson I, Lunell NO, Forman A, Skajaa K, Lindberg B, Lindeberg S, Marsal K, Andersson KE. Calcium channel blockade (isradipine) in treatment of hypertension in pregnancy: a randomized placebo-controlled study. Am J Obstet Gynecol 1995;173:872–8.

5.Maharaj B, Khedun SM, Moodley J, Madhanpall N, van der Byl K. Intravenous isradipine in the management of severe hypertension in pregnant and nonpregnant patients. A pilot study. Am J Hypertens 1994;7:61S–3S.

6.Kublickas M, Lunell NO, Grunewald C, Nisell H. Effect of isradipine on maternal renal artery pulsatility index in hypertensive pregnancy. Hypertens Pregnancy 1995;14:277–85.

7.Resch B, Mache CJ, Windhager T, Holzer H, Leitner G, Muller W. FK 506 and successful pregnancy in a patient after renal transplantation. Transplant Proc 1998;30:163–4.

8.Fletcher H, Roberts G, Mullings A, Forrester T. An open trial comparing isradipine with hydralazine and methyldopa in the treatment of patients with severe pre-eclampsia. J Obstet Gynaecol 2009;19:235–8.

9.Product information. DynaCirc. Sandoz Pharmaceuticals, 1993.



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