Labetalol hydrochloride

How it works

It blocks beta-1, beta-2 and peripheral alpha-1 adrenoceptors, reducing heart rate and cardiac output while lowering peripheral vascular resistance, producing a fall in blood pressure without marked reflex tachycardia.

Prescribing in practice

• As a non-selective beta-blocker it is contraindicated in asthma and should be used with great caution in any reversible airways disease because of the risk of bronchospasm.
• Intravenous use requires close haemodynamic monitoring, and patients should remain supine during and shortly after intravenous administration because of the risk of postural hypotension.
• It is a recognised first-line option for hypertension in pregnancy but can rarely cause severe hepatocellular injury.

Monitoring

Monitor blood pressure and heart rate closely (continuously during intravenous use), and review liver function if hepatic dysfunction is suspected.

Counselling the patient

• Do not stop this medicine suddenly, as abrupt withdrawal can worsen angina or raise blood pressure.
• After an intravenous dose, stay lying down for a while to avoid fainting when you stand.
• Report yellowing of the skin or eyes, dark urine or persistent nausea, which may signal a liver problem.

Evidence & guidelines

Labetalol is recommended by NICE as a first-line treatment for hypertension in pregnancy and is a long-established agent for hypertensive emergencies.