From the Guidelines
Oral labetalol dosing should start at 100 mg twice daily, with a maximum recommended daily dose of 2400 mg, as indicated by the expert consensus document on management of cardiovascular diseases during pregnancy 1. When initiating oral labetalol therapy, it is essential to consider the individual patient's needs and adjust the dose accordingly.
- The dose can be increased as needed to a usual maintenance dose of 200-400 mg twice daily.
- For patients who require higher doses, the maximum recommended daily dose is 2400 mg, though doses above 1200 mg daily are rarely needed, as stated in the expert consensus document 1.
- It is crucial to monitor patients for orthostatic hypotension, especially when initiating therapy or increasing doses.
- Labetalol should not be abruptly discontinued due to the risk of rebound hypertension; tapering is recommended when stopping treatment.
- Common side effects include dizziness, fatigue, and gastrointestinal disturbances. The expert consensus document 1 provides guidance on the management of cardiovascular diseases during pregnancy, including the use of oral labetalol, and its recommendations should be followed to ensure optimal patient outcomes.
From the FDA Drug Label
The peak effects of single oral doses of labetalol HCl occur within 2 to 4 hours. The duration of effect depends upon dose, lasting at least 8 hours following single oral doses of 100 mg and more than 12 hours following single oral doses of 300 mg. The maximum, steady-state blood pressure response upon oral, twice-a-day dosing occurs within 24 to 72 hours About 70% of the maximum beta-blocking effect is present for 5 hours after the administration of a single oral dose of 400 mg with suggestion that about 40% remains at 8 hours. Labetalol HCl is completely absorbed from the gastrointestinal tract with peak plasma levels occurring 1 to 2 hours after oral administration.
The oral dosing of labetalol has the following characteristics:
- Peak effects: within 2 to 4 hours
- Duration of effect: at least 8 hours for 100 mg, more than 12 hours for 300 mg
- Steady-state blood pressure response: within 24 to 72 hours with twice-a-day dosing
- Beta-blocking effect: 70% present for 5 hours, 40% remains at 8 hours after a 400 mg dose
- Absorption: complete, with peak plasma levels 1 to 2 hours after administration 2
From the Research
Oral Labetalol Dosing
- The initial dose of oral labetalol for the management of severe hypertension in pregnancy is 200 mg, which can be escalated hourly if hypertension is maintained 3.
- A systematic review of oral antihypertensive agents for the treatment of severe pregnancy/postpartum hypertension found that target blood pressure was achieved in approximately 50% of women with oral labetalol (100 mg) 4.
- A network meta-analysis of randomized controlled trials comparing different dosage regimens of nifedipine, labetalol, and hydralazine for the treatment of severe hypertension during pregnancy found that IV labetalol 220 mg and 300 mg were among the regimens compared, but the study did not provide specific information on the optimal dosing of oral labetalol 5.
- A study on the pharmacokinetics of antihypertensive drugs throughout pregnancy found that there is a need for further studies on the relationship between pharmacokinetics and pharmacodynamics of labetalol during pregnancy to prevent undertreatment, overtreatment, and side effects 6.
- A randomized clinical trial comparing methyldopa, labetalol, and no medication for the treatment of mild and moderate chronic hypertension during pregnancy found that labetalol was associated with higher rates of small for gestational age, neonatal hypotension, and neonatal hyperbilirubinemia compared to methyldopa or no medication 7.