From the FDA Drug Label
The plasma half-life of labetalol following oral administration is about 6 to 8 hours. The half-life of labetalol is 6 to 8 hours 1.
- The elimination half-life is not altered in patients with decreased hepatic or renal function.
- However, the relative bioavailability in hepatically impaired patients is increased due to decreased "first-pass" metabolism.
From the Research
The half-life of labetalol is approximately 3 to 6 hours in adults with normal hepatic and renal function. This beta-blocker has a relatively short half-life compared to some other antihypertensive medications, which means it typically requires dosing multiple times per day when used for ongoing blood pressure management. After oral administration, peak plasma concentrations occur within 1-2 hours. Labetalol is extensively metabolized by the liver, with less than 5% excreted unchanged in urine. Patients with liver impairment may experience a prolonged half-life and require dosage adjustments. The drug's elimination kinetics follow a biphasic pattern, with an initial rapid distribution phase followed by a slower elimination phase. This pharmacokinetic profile explains why the clinical effects of labetalol may persist longer than what the half-life alone would suggest, particularly after intravenous administration 2.
Some key points to consider when prescribing labetalol include:
- The bioavailability of labetalol can vary significantly between individuals, ranging from 10% to over 80% 3.
- The half-life of labetalol can be affected by factors such as liver function and age 3.
- Labetalol is often used to treat hypertension, and its efficacy has been demonstrated in several clinical studies 4, 5, 6.
- The most common side effects of labetalol include postural hypotension, gastrointestinal disturbances, and tiredness 4.
Overall, the half-life of labetalol is an important consideration when prescribing this medication, and healthcare providers should be aware of the potential factors that can affect its pharmacokinetics and pharmacodynamics.