Nifedipine

How it works

It blocks L-type calcium channels in vascular and uterine smooth muscle, causing vasodilatation that lowers blood pressure and reducing myometrial contractility.

Prescribing in practice

• Use modified-release rather than rapid-acting formulations for blood pressure control, as abrupt vasodilatation can cause precipitous hypotension and compromise uteroplacental perfusion.
• Headache, flushing, ankle oedema and palpitations are common dose-related effects.
• Caution is needed with concurrent magnesium sulfate because of the potential for additive hypotension and neuromuscular effects.

Monitoring

Monitor maternal blood pressure and heart rate, and observe the fetus, particularly when used for tocolysis or alongside magnesium sulfate.

Counselling the patient

• Headache and flushing often settle after the first few days.
• Take the modified-release tablets whole and do not stop suddenly.
• Report severe dizziness, fainting or palpitations.

Evidence & guidelines

NICE guidance lists nifedipine as an option for hypertension in pregnancy, and trial evidence supports calcium-channel blockade for tocolysis in preterm labour.