Special features

Hypertension — pharmacological management

By Beth Gormer, MPharm, MRPharmS

This article describes the mode of action of drugs used in the treatment of hypertension, their side effects and factors to consider in special patient groups. Recent guidelines from the National Institute for Health and Clinical Excellence are also described

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Beth Gormer is cardiology pharmacist at the Royal Sussex County Hospital, Brighton

Sidney Moulds/SPL

Crystals of the beta-blocker propranolol

Crystals of the beta-blocker propranolol (polarised light micrograph)

SUMMARY

Hypertension is a risk factor for many coronary events. However, blood pressure can usually be reduced with appropriate treatment, reducing the risk of stroke, coronary events, heart failure and renal failure.

Many different factors are involved in the pathogenesis of hypertension. These include increased cardiac output, increased peripheral resistance, vasoconstriction and reduced vasodilation. The kidneys also play a role in the regulation of blood pressure by controlling sodium and water excretion, and the secretion of renin, which influences vascular tone and electrolyte imbalance. Neuronal mechanisms such as the sympathetic nervous system and endocrine systems are also involved in blood pressure regulation. These systems are therefore targets for drug therapy to reduce blood pressure.

Target blood pressures The optimal systolic blood pressure (SBP) is <140mmHg and the optimal diastolic blood pressure (DPB) is <85mmHg. A target SBP of 130mmHg and DPB of <80mmHg should be considered for patients with established atherosclerotic cardiovascular disease, diabetes or chronic renal failure.

Regardless of the severity of hypertension, all patients should be offered lifestyle advice to reduce their blood pressure. This includes advice on smoking cessation, weight reduction, exercise, alcohol intake and diet.

Drug classes Commonly used classes of antihypertensive drugs are the thiazide diuretics (eg, bendroflumethiazide), beta-blockers (eg, propranolol, atenolol), angiotensin-converting enzyme inhibitors (eg, captopril, enalapril), angiotensin II antagonists (eg, candesartan, losartan), calcium channel blockers (eg, amlodipine, nifedipine) and alpha-blockers (eg, doxazosin).

Less commonly used drugs include vasodilator and centrally acting antihypertensives and, rarely, guanethidine, which is indicated for the treatment of hypertensive crisis.

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