In hypertensive crises for emergency lowering of blood pressure in adults with severe, nonmalignant and malignant (severe accelerated) hypertension and in children with acute severe hypertension. Short-term use in hospitalization. In malignant hypertension associated with renal impairment. Management of hypoglycemia caused by hyperinsulinism associated with inoperable islet cell adenoma or carcinoma, or extrapancreatic malignancy in adults, and with leucine sensitivity, islet cell hyperplasia, nesidioblastosis, extrapancreatic malignancy, islet cell adenoma, or adenomatosis in infants and children.