Expeditious reduction of blood pressure in severe hypertensive conditions has been commonly accomplished with a rapid intravenous bolus injection of a 300-mg dose of diazoxide , a potent direct vasodilator. Rapid bolus administration was seen to be necessary in order to exceed the binding capacity of serum albumin. However, precipitous hypotension, seen at times, caused myocardial or cerebral ischemic damage in some patients. The authors managed 18 patients whose mean initial BP was 220/143 mm Hg by treating with a slow diazoxide infusion. Nine patients re: ceived 15 mg/min and nine patients received 30 mg/min, with an end point of a diastolic BP of 105 mm Hg or less. No other medications were used. Sixteen of the 18 patients achieved a diastolic BP of 100 to 105 mm Hg. Average infusion time was 38.1 minutes in the 15 mg/min group and 20.7 minutes in the 30 rag/rain group. There were no hypotensive episodes or evidence of organ hypoperfusion. The mean heart rate rose from 83.4 to 97.2 beats per minute. Total diazoxide administered averaged 7.37 mg/kg in the 15 mg/min group and 8.65 mg/kg in the 30 mg/min group. The authors conclude that, although more experience is needed with this technique, slow diazoxide infusion is as efficacious as, and safer than, rapid bolus injection of a fixed dose.
Marc Kobernick, MD