Intravenous drugs used in treating hypertensive emergencies.

Drugs used to treat hypertensive emergencies should have the characteristics of rapid action, short duration, high potency, reversibility, a low toxic/therapeutic ratio, no association tachyphylaxis, and a specific action on the cardiovascular system. Of the three mentioned only SNP fulfills all of the requirements. SNP is used, with few exceptions, to treat hypertensive crisis. Trimethaphan camsylate is useful in preventing hemorrhage secondary to a dissecting aneurysm; the other drugs may worsen the tear. Diazoxide is good when no prolonged monitoring is available, since the drug is administered as a bolus rather than an infusion. Side effects, contraindications, and drug interactions are important points to remember during administration of these medications. Care is directed toward limiting or avoiding side effects by titrating the drug and by close observation of the patient. Concurrent maintenance therapy must be initiated to prevent a recurrence of hypertension upon discontinuance of the acute drug protocol.