MALIGNANT HYPERTENSION: PHARMACOTHERAPY

Malignant Hypertension is a rare case but very serious form of sever high blood pressure, in which high blood pressure is accompanied by internal bleeding of the retinas in both eyes and swelling of optic nerves behind the retinas also can cause severe organ damage and possibly death and hence one should get serious medical attention as soon as possible.

Up to 1% of patients with essential hypertension develop malignant hypertension, but the reason some patients develop malignant hypertension whereas others do not is unknown. (Bisognano, 2011). The characteristic vascular lesion is fibrinoid necrosis of arterioles and small arteries, which causes the clinical manifestations of end-organ damage.

The initial goal of therapy is to reduce the mean arterial pressure by approximately 25% over the first 24-48 hours. An intra-arterial line is helpful for continuous monitoring of blood pressure. Sodium and volume depletion may be severe, and volume expansion with isotonic sodium chloride solution must be considered. (Pergolini, 2009) Secondary causes of hypertension should be investigated.

The most commonly used intravenous drug is nitroprusside a short acting drug which increase cGMP via direct release of nitric oxide, and then smooth muscle relaxation. (Tao, Bhushan, & Tolles, 2011). An alternative for patients with renal insufficiency is intravenous fenoldopam a dopamine D1 receptor agonist that relaxes renal vascular smooth muscle, another choice in a malignant hypertension is a K channel opener, diazoxide which produces a hyperpolarized and relaxes vascular smooth muscle.

However, a trial by Peacock et al demonstrated that intravenous calcium blockers (eg, nicardipine) could be useful in quickly and safely reducing blood pressure to target levels and seemed more effective than intravenous labetalol. (Peacok, Varon, & Baumann, 2011).

Beta-blockade can be accomplished intravenously with esmolol or metoprolol. Also available parenterally are diltiazem, verapamil, and enalapril. Hydralazine is reserved for use like first-line therapy in pregnant patients, associated with methyldopa, frequently co-administered with a β-blocker to prevent reflex tachycardia; whereas phentolamine is the drug of choice for a pheochromocytoma crisis. Oral medications should be initiated as soon as possible in order to ease transition to an outpatient setting.

Bibliography

Bisognano, J. D. (2011, sep 27). Medscape.com. Retrieved from Malignant Hypertension: http://emedicine.medscape.com/article/241640-overview

Peacok, W., Varon, J., & Baumann, B. (2011, ;15(3):R157 (ISSN: 1466-609X)). medscape.com. Retrieved from CLUE: a randomized comparative effectiveness trial of IV nicardipine & labetalol use in the emergency department. Crit Care.: http://reference.medscape.com/medline/abstract/21707983

Pergolini, M. (2009, ;160(2):151-7 (ISSN: 1972-6007)). medsape.com. Retrieved from The management of hypertensive crises: a clinical review. lin Ter.: http://reference.medscape.com/medline/abstract/19452106

Tao, L., Bhushan, V., & Tolles, J. (2011). First AID for the USMLE step 1. usa: McGraw Hill.