Intravenous Labetalol: Pharmacokinetics and Dosing Guidelines

Onset and Duration of Action

• Intravenous labetalol begins lowering blood pressure within 1–2 minutes after a bolus, reaching its maximal hemodynamic effect at approximately 5 minutes. 2
• The antihypertensive effect of a single IV bolus persists for 3–6 hours before blood pressure gradually returns toward baseline. 1, 2

Dosing Strategies

Bolus Administration

• Recommended bolus dose is 10–20 mg given over 1–2 minutes, with the option to repeat every 10–20 minutes as needed, not exceeding a cumulative total of 300 mg. 3, 4, 5

Continuous Infusion

• Initiate continuous infusion at 2 mg/min (approximately 0.5–1 mg/kg/h) and adjust the rate based on the patient’s blood pressure response. 1, 6

Titration Guidance

• Because of its rapid onset, blood pressure can be titrated in 10‑minute intervals after each bolus, producing predictable reductions in systolic and diastolic pressures. 3, 5, 7