Labetalol in resistant hypertension.

1 The efficacy of labetalol in lowering blood pressure has been assessed in a group of 16 patients with severe hypertension whose blood pressure was inadequately controlled (supine diastolic blood pressure greater than 110 mmHg on two consecutive occasions) on existing therapy or in whom severe side-effects necessitated a change in therapy. 2 All patients had an original pretreatment supine diastolic blood pressure of greater than 120 mmHg and most had evidence of target organ damage. Patients were hospitalized for the purposes of changeover of therapy, labetalol being added to the existing regime which was reduced stepwise and eventually withdrawn. 3 Treatment with labetalol resulted in satisfactory blood pressure control in 10 of 16 patients in this study but high doses were required, the mean daily dose being 3,091 mg (range 1,200-8,000). 4 Treatment with discontinued in 6 patients on account of postural hypotension (3), failure to control supine diastolic blood pressure (2) and retention of urine (1). Long-term treatment was relatively free from side-effects. 5 From preliminary studies in animals it is suggested that an action within the central nervous system may contribute to the hypotensive effect of labetalol.