What is the dosage for Labetalol?

Labetalol Dosing

For hypertensive emergencies, administer labetalol 10-20 mg IV over 1-2 minutes, repeating or doubling every 10-20 minutes up to a maximum cumulative dose of 300 mg, or alternatively use a continuous infusion at 2-8 mg/min. 1

Intravenous Dosing for Hypertensive Emergencies

Acute Ischemic Stroke

For patients NOT eligible for thrombolytic therapy:

• Systolic >220 mmHg or diastolic 121-140 mmHg: Labetalol 10-20 mg IV over 1-2 minutes, may repeat or double every 10 minutes to maximum dose of 300 mg 1
• Target: 10-15% reduction in blood pressure 1, 2

For patients ELIGIBLE for thrombolytic therapy:

• Pre-treatment (systolic >185 mmHg or diastolic >110 mmHg): Labetalol 10-20 mg IV over 1-2 minutes, may repeat once 1, 2
• During/after treatment (systolic 180-230 mmHg or diastolic 105-120 mmHg): Labetalol 10 mg IV over 1-2 minutes, may repeat or double every 10-20 minutes to maximum 300 mg, OR initial 10 mg IV followed by infusion at 2-8 mg/min 1, 2
• During/after treatment (systolic >230 mmHg or diastolic 121-140 mmHg): Same dosing as above 1, 2
• Goal: Maintain blood pressure <185/110 mmHg before administering rtPA 1, 2

Other Hypertensive Emergencies

• Non-stroke emergencies: Initial dose 0.3-1.0 mg/kg (maximum 20 mg) slow IV injection every 10 minutes, maximum cumulative dose 300 mg, may repeat every 4-6 hours 2
• Acute aortic disease: Target systolic BP ≤120 mmHg and heart rate ≤60 bpm 3
• Hemorrhagic stroke: Target systolic BP <180 mmHg 3
• Severe pre-eclampsia/eclampsia: First-line therapy with target systolic <160 mmHg and diastolic <105 mmHg; cumulative dose should not exceed 800 mg/24h to prevent fetal bradycardia 3

Oral Dosing for Chronic Hypertension

Initial dose: 100 mg twice daily, whether used alone or with a diuretic 4

Titration: After 2-3 days, increase in increments of 100 mg twice daily every 2-3 days based on standing blood pressure 4

Usual maintenance: 200-400 mg twice daily 4

Severe hypertension: May require 1,200-2,400 mg per day 4

Maximum dose: 2,400 mg daily 2, 4

Alternative dosing for side effects: If nausea or dizziness occurs with twice-daily dosing, divide the same total daily dose into three times daily; titration increments should not exceed 200 mg twice daily 4

Elderly patients: Initiate at 100 mg twice daily and titrate upwards in 100 mg increments; most elderly patients require only 100-200 mg twice daily due to slower elimination 4

Pregnancy: May require three or four times daily dosing due to accelerated drug metabolism during pregnancy 2

Monitoring Requirements

For thrombolytic therapy patients: Check blood pressure every 15 minutes for 2 hours, then every 30 minutes for 6 hours, then every hour for 16 hours 1

For hemorrhagic stroke: Monitor blood pressure every 15 minutes until stabilized for the first 24-48 hours 3

General monitoring: The full antihypertensive effect is usually seen within 1-3 hours of initial dose or dose increment 4

Critical Contraindications

Absolute contraindications:

• Second or third-degree heart block 3, 2
• Bradycardia 3
• Decompensated heart failure 3, 2
• Reactive airways disease or COPD 2

Important Clinical Pearls

• Labetalol is particularly useful in hyperadrenergic states due to its combined alpha- and beta-blocking properties 3, 2
• In hypertensive encephalopathy, labetalol may be preferred as it leaves cerebral blood flow relatively intact compared to nitroprusside 3
• When adding a diuretic, expect an additive antihypertensive effect that may necessitate dose reduction 4
• High-dose IV labetalol (>300 mg/24h) has been studied with mean doses of 996 mg showing 44% adverse event rate (primarily bradycardia 36.5% and hypotension 18.6%), but only 2.7% required rescue agents, suggesting these events rarely cause clinically significant hemodynamic compromise 5
• Fluid retention is frequent but easily controlled with diuretics 6
• Abrupt discontinuation does not cause blood pressure overshoot 7