Labetalol
- Class: Alpha/beta blocker
- Used for: hypertensive emergency
- Say it: luh-BET-uh-lol
- Forms: tablet, injection
LABETALOL is the beta blocker for LABOUR — the one that is safe when a pregnant woman's pressure climbs.
It has a long record of fetal safety and is first-line in pregnancy and pre-eclampsia. Its extra alpha-1 blockade brings the pressure down smoothly, without the reflex fast pulse a pure vasodilator causes.
Most beta blockers slow the heart but leave vessels constricted. Labetalol blocks alpha-1 too, so it drops resistance at the same time — a controlled fall rather than a crash, and safe in pregnancy.
Side effects
Common: dizziness, fatigue, scalp tingling
Serious: liver injury, bronchospasm
Typical dose
100 mg twice daily orally, up to 2400 mg daily
Orally, increase every few days. Intravenously, 20 mg slowly, then doubling boluses every 10 minutes up to 300 mg total.
Check yourself
What distinguishes labetalol from a beta blocker such as metoprolol?
- It also blocks alpha-1 receptors, so it dilates vessels as well as slowing the heart
- It is selective for beta-1 receptors only
- It raises the heart rate
- It acts on calcium channels
Show answer
A. It also blocks alpha-1 receptors, so it dilates vessels as well as slowing the heart
A pure beta blocker can leave peripheral resistance high, or even raise it through unopposed alpha stimulation. Labetalol's additional alpha-1 blockade removes that problem, which is why it suits hypertensive emergencies.
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