USE OF CALCIUM CHANNEL BLOCKERS IN PREGNANCY

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(Date of issue: July 2016, Version: 1)

This is a UKTIS monograph for use by health care professionals. For case-specific advice please contact UKTIS on 0344 892 0909. To report an exposure please download and complete a pregnancy reporting form. Please encourage all women to complete an online reporting form.

A corresponding patient information leaflet on calcium channel blocker use in pregnancy is available at www.medicinesinpregnancy.org.

Summary

Calcium channel blockers (CCBs) (amlodipine, diltiazem, felodipine, lacidipine, lercanidipine, nicardipine, nifedipine, nimodipine, and verapamil) are mainly used for the treatment and prophylaxis of angina, and the treatment of hypertension where an ACE inhibitor/angiotensin 2 receptor antagonist is unsuitable. Additionally, nifedipine is used to treat Reynaud’s phenomenon and as a tocolytic to delay or prevent premature labour; nimodipine is used for the prevention and treatment of ischaemic neurological deficits following aneurysmal subarachnoid haemorrhage; verapamil is used to treat supraventricular arrhythmias and for the prophylaxis of cluster headaches. Topical diltiazem (2%) is also used off-license to treat anal fissure.

National Institute of Health and Care Excellence (NICE) guidelines state that where labetalol is not an appropriate first-line treatment, nifedipine may be used to treat hypertension in pregnancy. 

Data on overall rates of fetal structural malformation or of the risk of specific malformations following first trimester use of CCBs, although unconcerning, are currently too limited to rule out an increased risk. Three studies found no association between gestational exposure to calcium channel blockers and congenital heart defects, although overall numbers studied are small and confounded, therefore these findings remain to be confirmed. A single study found an association between upper alimentary tract malformations and exposure to CCBs in early pregnancy, but this was based on a small number of exposed cases and requires confirmation with further research. Animal studies have suggested that exposure to some CCBs in early pregnancy is associated with phalangeal defects in the offspring, and although human case reports of phalangeal defects following in utero CCB exposure exist, controlled human studies have not identified an increased rate of limb defects or polydactyly but are not sufficiently powered to confirm the absence of an association.

A small but statistically robust study that assessed rates of spontaneous abortion following exposure to CCBs in early pregnancy found no increased risk. Further research is required to confirm this finding. On balance, the limited available data do not support an increased risk of intrauterine death following exposure to nifedipine in pregnancy, however further adequately powered studies are required to confirm this and IUD/stillbirth risk for other CCBs. Data on rates of preterm delivery, fetal growth and neurodevelopmental outcomes are too limited and/or confounded to permit an accurate risk assessment, but where a CCB is required to treat maternal hypertension or as a tocolytic, fetal benefits of use are likely to outweigh any unspecified risk and treatment should not be withheld on this basis.

Exposure to a calcium channel blocker at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy. In pregnancies complicated by maternal hypertension or threatened preterm labour, additional fetal monitoring is advised. Other risk factors may also be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.
                                       
This document is regularly reviewed and updated. Only use full UKTIS monographs downloaded directly from TOXBASE.org to be sure you are using the most up-to-date version. The summaries of these monographs are openly available on UKTIS.org.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to health care professionals at www.toxbase.org.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from TOXBASE.org or UKTIS.org to ensure you are using the most up-to-date version.