Combined intravenous administration of diazoxide and beta-blocking agent in acute treatment of severe hypertension or hypertensive crisis.

Twenty-nine patients with severe hypertension (n = 14) or hypertensive crisis (n = 15) were treated with diazoxide infusion and intravenous injection of a beta blocker. In 13 patients diazoxide was administered first. It gradually reduced mean arterial pressure (MAP) by 16.1 +/- 2.1% (mean +/- SEM), and increased heart rate (HR) by 27.3 +/- 4.1% and plasma renin activity (PRA) by 48.9 +/- 13.0%. Beta blockade thereafter lowered MAP by only 1.2 +/- 1.9% despite reductions of HR by 35.6 +/- 2.2% and of PRA by 17.1 +/- 5.9%. In 16 other patients a beta blocker, when given first, reduced MAP by 3.5 +/- 1.2%, HR by 18.9 +/- 1.8%, and PRA by 24.2% +/- 4.4%. Diazoxide infusion thereafter gradually reduced MAP further by 21.9 +/- 1.9% and raised HR and PRA to pretreatment levels. No complications were observed. Beta blockade before diazoxide infusion effectively prevents a rise in HR above control levels while its acute effect on blood pressure is negligible. It is advisable to use this combined treatment in all situations where the occurrence of tachycardia might be dangerous.