What is the recommended dose of labetalol (beta blocker) for treating hypertension?

Labetalol Dosing for Hypertension

Oral Dosing for Chronic Hypertension Management

For chronic hypertension, start labetalol at 100 mg twice daily and titrate upward in 100 mg increments every 2-3 days based on blood pressure response, with a usual maintenance dose of 200-400 mg twice daily and a maximum of 2400 mg daily. 1

Initial Dosing Strategy

• Begin with 100 mg twice daily, whether used alone or added to a diuretic 1
• Assess standing blood pressure after 2-3 days to guide titration 1
• The full antihypertensive effect occurs within 1-3 hours of each dose, allowing office-based assessment of tolerability 1

Titration Protocol

• Increase by 100 mg twice daily every 2-3 days until blood pressure control is achieved 1
• Most patients achieve adequate control with 200-400 mg twice daily 2, 1
• For severe hypertension, doses may range from 1200-2400 mg daily 1
• If side effects (nausea, dizziness) occur with twice-daily dosing, divide the same total daily dose into three times daily administration 1
• Never exceed 200 mg per titration increment when dosing twice daily 1

Special Population Considerations

• Elderly patients: Start at 100 mg twice daily; most achieve control with 100-200 mg twice daily due to slower drug elimination 1
• Pregnant patients: May require three or four times daily dosing due to accelerated drug metabolism during pregnancy 2
• With diuretic therapy: Lower maintenance doses are typically needed; expect additive antihypertensive effects 1

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Intravenous Dosing for Hypertensive Emergencies

For hypertensive emergencies, administer labetalol 10-20 mg IV over 1-2 minutes, repeating or doubling the dose every 10 minutes up to a maximum cumulative dose of 300 mg, or use continuous infusion at 0.4-1.0 mg/kg/hour up to 3 mg/kg/hour. 3

IV Bolus Dosing

• Initial dose: 10-20 mg IV over 1-2 minutes 3, 2
• Repeat or double the dose every 10 minutes as needed 3
• Maximum cumulative bolus dose: 300 mg in standard practice 3, 2
• Alternative dosing: 0.3-1.0 mg/kg (maximum 20 mg) slow IV injection every 10 minutes 2

Continuous Infusion Protocol

• Initial rate: 0.4-1.0 mg/kg/hour (approximately 30-80 mg/hour for a 70-80 kg adult) 3
• Maximum rate: 3 mg/kg/hour (approximately 200-240 mg/hour for a 70 kg patient) 3
• Alternative starting rate: 2 mg/min (2 mL/min), titrated to blood pressure response 3

Practical Infusion Dosing Ranges

• Low-dose: 30-50 mg/hour (0.4-0.7 mg/kg/hour for 70 kg patient) 3
• Moderate-dose: 70-120 mg/hour (1.0-1.7 mg/kg/hour for 70 kg patient) 3
• High-dose: 150-210 mg/hour (2.1-3.0 mg/kg/hour for 70 kg patient) 3

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Clinical Scenario-Specific Dosing

Acute Ischemic Stroke

• Thrombolytic-eligible patients (BP >185/110 mmHg): Give 10-20 mg IV over 1-2 minutes; may repeat once, then maintain BP <185/110 mmHg 3, 2
• Non-thrombolytic patients (systolic >220 mmHg or diastolic 121-140 mmHg): Give 10-20 mg IV over 1-2 minutes, targeting 10-15% BP reduction 3, 2

Acute Hemorrhagic Stroke

• Target systolic BP <180 mmHg using labetalol infusion 3
• Use infusion rates of 0.4-1.0 mg/kg/hour up to 3 mg/kg/hour 3

Severe Preeclampsia/Eclampsia

• Initial dose: 20 mg IV bolus, then 40 mg after 10 minutes, then 80 mg every 10 minutes for 2 additional doses (maximum 220 mg) 2
• Alternative: Continuous infusion at 0.4-1.0 mg/kg/hour up to 3 mg/kg/hour 3
• Target: Systolic BP <160 mmHg and diastolic BP <105 mmHg 3
• Maximum cumulative dose: 800 mg/24 hours to prevent fetal bradycardia 3

Acute Aortic Dissection

• Target systolic BP ≤120 mmHg and heart rate ≤60 bpm 3
• Use labetalol as first-line therapy with ultra-short acting vasodilators 3

Malignant Hypertension/Hypertensive Encephalopathy

• Goal: Reduce mean arterial pressure by 20-25% over several hours 3
• Use continuous infusion at 0.4-1.0 mg/kg/hour up to 3 mg/kg/hour 3

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Blood Pressure Targets and Monitoring

Target Blood Pressure Reductions

• General hypertensive emergencies: Reduce mean arterial pressure by 20-25% over several hours 3
• Acute ischemic stroke: 10-15% reduction 3, 2
• Acute hemorrhagic stroke: Systolic BP <180 mmHg 3
• Thrombolytic-eligible stroke: Maintain BP <185/110 mmHg 3, 2

Monitoring Frequency

• First 2 hours: Every 15 minutes 3
• Next 6 hours: Every 30 minutes 3
• Subsequent 16 hours: Every hour 3
• For acute hemorrhagic stroke: Every 15 minutes until stabilized for first 24-48 hours 3

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Absolute Contraindications

Do not use labetalol in patients with the following conditions, regardless of dose: 3, 2

• Second- or third-degree heart block 3, 2
• Bradycardia 3, 2
• Decompensated heart failure 3, 2
• Reactive airways disease (asthma) 3, 2
• Chronic obstructive pulmonary disease (COPD) 3, 2

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Critical Safety Considerations

Common Pitfalls

• Avoid rapid or excessive BP falls: Target gradual reduction over several hours, not minutes 3
• Do not exceed 300 mg cumulative bolus dose without switching to infusion in standard practice 3, 2
• Monitor for profound cardiovascular compromise with prolonged infusions, particularly in critically ill patients 4
• Have reversal agents readily available: Glucagon, beta-agonists, phosphodiesterase inhibitors, insulin, and vasopressin should be accessible when using continuous infusions 4

Common Adverse Effects

• Hypotension, bradycardia, nausea, scalp tingling, and burning sensations 3
• Fluid retention (easily controlled with diuretics) 5
• Postural hypotension, particularly with initial dosing 5

Drug Interactions

• Additive effects with diuretics: Expect enhanced BP reduction; lower labetalol doses may be needed 1
• Pregnancy considerations: Labetalol is safe during pregnancy with minimal teratogenicity risk, but may be less effective postpartum compared to calcium channel blockers 3, 2