Labetalol

How it works

Labetalol blocks beta-adrenoceptors to reduce heart rate and cardiac output while also blocking alpha-1 receptors to cause vasodilatation, lowering blood pressure without a marked reflex tachycardia.

Prescribing in practice

• It should be avoided in women with asthma because of the risk of bronchospasm, and beta-blockade can mask and modify hypoglycaemia, which is relevant in diabetic pregnancy and the neonate.
• Neonates of treated mothers should be observed for bradycardia and hypoglycaemia after delivery.
• It is a preferred oral and intravenous agent for hypertension in pregnancy and is used both for maintenance control and acute severe hypertension in a monitored setting.

Monitoring

Monitor maternal blood pressure and heart rate, and observe the neonate for hypoglycaemia and bradycardia following delivery.

Counselling the patient

• Take this regularly to keep your blood pressure controlled and do not stop suddenly without advice.
• Tell your midwife or doctor if you have asthma or wheezing, or if you feel dizzy on standing.
• Your baby will be checked after birth for a slow heartbeat or low blood sugar.

Evidence & guidelines

NICE guidance on hypertension in pregnancy recommends labetalol as a first-line antihypertensive for chronic, gestational and pre-eclamptic hypertension.