From the Guidelines
IV labetalol for hypertension is typically administered as an initial 0.3–1.0-mg/kg dose (maximum 20 mg) slow IV injection every 10 min or 0.4–1.0-mg/kg/h IV infusion up to 3 mg/kg/h, with a total cumulative dose of 300 mg, as recommended by the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline 1.
Key Considerations
- The dose can be repeated every 4–6 h as needed to achieve the desired blood pressure.
- Labetalol works as both an alpha and beta-adrenergic blocker, providing rapid blood pressure reduction while maintaining cerebral perfusion.
- It is particularly useful in hypertensive emergencies such as stroke, aortic dissection, and preeclampsia.
Monitoring and Precautions
- Blood pressure and heart rate should be monitored closely during administration, with measurements taken at least every 5 minutes during the initial treatment phase.
- Caution should be exercised in patients with bradycardia, heart block, bronchospastic disease, or heart failure, as labetalol can exacerbate these conditions.
Onset and Duration of Action
- The onset of action is typically within 5 minutes, with peak effects occurring at 5-15 minutes and duration of action lasting 2-4 hours.
Alternative Administration
- Alternatively, after the initial bolus, labetalol can be given as a continuous infusion at 1-2 mg/min, titrated to the desired blood pressure.
- The maximum infusion rate is 3 mg/kg/h, and the maximum total cumulative dose is 300 mg.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Labetalol HCl Injection is intended for intravenous use in hospitalized patients. DOSAGE MUST BE INDIVIDUALIZED depending upon the severity of hypertension and the response of the patient during dosing. Either of two methods of administration of labetalol HCl injection may be used: a) repeated intravenous injections, b) slow continuous infusion Repeated Intravenous Injection Initially, labetalol HCl injection should be given in a dose of 20 mg labetalol HCl (which corresponds to 0. 25 mg/kg for an 80 kg patient) by slow intravenous injection over a 2-minute period. Additional injections of 40 mg or 80 mg can be given at 10-minute intervals until a desired supine blood pressure is achieved or a total of 300 mg labetalol HCl has been injected
The initial dose for IV labetalol is 20 mg given over 2 minutes, with additional doses of 40 mg or 80 mg given at 10-minute intervals as needed, up to a total of 300 mg 2.
- Key points:
- The dosage must be individualized based on the severity of hypertension and patient response.
- The maximum effect usually occurs within 5 minutes of each injection.
- Blood pressure should be monitored during and after completion of the infusion or intravenous injections.
From the Research
IV Labetalol Dosage for Hypertension
- The average hourly dose of labetalol was 37.3 ± 9.4 mg/h, with an average total dose of 170.9 ± 32.6 mg 3.
- The duration of therapy was significantly shorter for labetalol (8.2 ± 6.2 hours) compared with nicardipine (15.8 ± 4.4 hours) 3.
- A study found that the initial mini-bolus injection of labetalol (20 mg) caused rapid but not abrupt reduction in blood pressure, with further injections needed in the majority of patients (mean: 197 mg) 4.
Comparison with Nicardipine
- Nicardipine was associated with fewer adverse effects, including less hypotension and bradycardia or atrioventricular block, compared with labetalol 3.
- A systematic review found comparable efficacy and safety for nicardipine and labetalol, although nicardipine appeared to provide more predictable and consistent BP control than labetalol 5.
- In patients with renal dysfunction, nicardipine was more efficacious than labetalol for acute blood pressure control, with more patients achieving the target blood pressure range within 30 minutes 6.
Specific Patient Populations
- In stroke patients, continuous-infusion labetalol and nicardipine were comparable in terms of safety and efficacy outcomes, including time at goal and BP variability 7.
- In patients with severe hypertension and hypertensive emergencies, labetalol was found to be a safe and effective treatment for rapid blood pressure reduction 4.