Hydralazine (IV — Acute Hypertension in Pregnancy)

How it works

Hydralazine relaxes arteriolar smooth muscle, reducing systemic vascular resistance and arterial pressure; the resulting fall in blood pressure can trigger a reflex tachycardia.

Prescribing in practice

• Blood pressure can fall abruptly, risking maternal hypotension and reduced uteroplacental perfusion with fetal distress, so it must be given by titrated doses with continuous maternal and fetal monitoring, and intravenous fluid co-loading is often considered.
• Reflex tachycardia, headache, flushing and fluid retention are common and the clinical picture can mimic worsening pre-eclampsia.
• It is one of several first-line options for acute severe hypertension in pregnancy and is administered only in a monitored obstetric or critical-care setting.

Monitoring

Monitor maternal blood pressure and heart rate frequently alongside cardiotocographic fetal monitoring during and after administration.

Counselling the patient

• This medicine is given by drip or injection to bring dangerously high blood pressure down quickly and protect you and your baby.
• You and your baby will be closely monitored throughout.
• Tell staff if you feel faint, develop a pounding heartbeat or a severe headache.

Evidence & guidelines

NICE guidance on hypertension in pregnancy lists intravenous hydralazine among first-line agents for acute severe hypertension, used with careful titration and monitoring.