Intravenous labetalol in the treatment of severe hypertension.

1 We have compared, in patients with severe hypertension, the administration of intravenous labetalol by single rapid injection, by repeated bolus injections, and by incremental infusion. 2 Incremental infusion was the most consistently (albeit not invariably) effective method, and that least prone to cause side-effects. 3 An occasional very marked decrease in blood pressure was seen with all these techniques but least often with incremental infusion. Thus close and continuous supervision is mandatory. 4 All three methods produced slight but significant decreases in heart rate, and in plasma angiotensin II and aldosterone. 5 Intravenous labetalol was also effective in controlling hypertensive crises of phaeochromocytoma and those following the withdrawal of clonidine. 6 In a total of 70 severely hypertensive patients given intravenous labetalol, none showed adverse neurological or cardiological sequelae.