Comparison of labetalol, clonidine and diazoxide intravenously administered in severe hypertension.

Diazoxide, clonidine and labetalol, administered intravenously in fixed doses, were used to treat 30 episodes of severe hypertension in 27 patients. Labetalol in a fixed dose of 100 mg proved ineffective treatment. Diazoxide 300 mg and clonidine 300 micrograms were comparable in effectiveness. Drowsiness was a common side effect with administration of clonidine (in six of 10 patients) and severe hypotension occurred in one patient who was given diazoxide.