Rapid onset of action of oral labetalol in severe hypertension.

Nine patients with persistently elevated diastolic blood pressure, exceeding 130 mmHg, received an oral dose of labetalol ranging from 200 mg to 400 mg. In all patients, this produced a significant and gradual decline in recumbent systolic and diastolic blood pressure, unaccompanied by symptoms or complications, with only minor changes in heart rate. Individual variation in the rate of blood pressure fall suggested differences in absorption and first-pass metabolism. It is suggested that the efficacy of oral labetalol merits further investigation in the rapid control of severe hypertension.