Antihypertensives are a class of drugs that are used in medicine and pharmacology to treat hypertension (high blood pressure). There are many classes of antihypertensives, which—by varying means—act by lowering blood pressure. Evidence suggests that reduction of the blood pressure by 5-6 mmHg can decrease the risk of stroke by 40%, of coronary heart disease by 15-20%, and reduces the likelihood of dementia, heart failure, and mortality from cardiovascular disease.

Which type of medication to use initially for hypertension has been the subject of several large studies. The JNC7 (The Seventh Report of the Joint National Committee on Prevention of Detection, Evaluation and Treatment of High Blood Pressure) recommends starting with a thiazide diuretic if single therapy is being initiated and another medication is not indicated. This is based on a slightly better outcome for chlortalidone in the ALLHAT study versus other anti-hypertensives and because thiazide diuretics are relatively cheap. A subsequent smaller study (ANBP2) published after the JNC7 did not show this small difference in outcome and actually showed a slightly better outcome for ACE-inhibitors in older male patients.

Despite thiazides being cheap, effective, and recommended as the best first-line drug for hypertension by many experts, they are not prescribed as often as some newer drugs. Arguably, this is because they are off-patent and thus rarely promoted by the drug industry.

The fundamental goal of treatment should be the prevention of the important "endpoints" of hypertension such as heart attack, stroke and heart failure. Several classes of medications are effective in reducing blood pressure. However, these classes differ in side effect profiles, ability to prevent endpoints, and cost. The choice of more expensive agents, where cheaper ones would be equally effective, may have negative impacts on national healthcare budgets.

Available drugs

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Diuretics

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and blood.

• Loop diuretics:
  • bumetanide
  • ethacrynic acid
  • furosemide
  • torsemide
• Thiazide diuretics:
  • chlortalidone
  • epitizide
  • hydrochlorothiazide and chlorothiazide
• Thiazide-like diuretics:
  • indapamide
  • metolazone
• Potassium-sparing diuretics:
  • amiloride
  • triamterene

Although the above is a thorough list of diuretic agents, only the thiazide and thiazide-like diuretics have good evidence of beneficial effects on important endpoints of hypertension.

Antiadrenergics

Adrenergic receptor antagonists:

• Beta blockers:
  • atenolol
  • metoprolol
  • oxprenolol
  • pindolol
  • propranolol
• Alpha blockers:
  • doxazosin
  • prazosin
  • terazosin
• Mixed Alpha + Beta blockers:
  • labetalol

Although beta blockers lower blood pressure, they do not have as positive a benefit on endpoints as some other antihypertensives. In particular, atenolol seems to be less useful in hypertension than several other agents. However, beta blockers have an important role in the prevention of heart attack in people who have already had a heart attack.

Despite lowering blood pressure, alpha blockers have significantly poorer endpoint outcomes than other antihypertensives, and are no longer recommended as a first-line choice in the treatment of hypertension. However, they may be useful for some men with symptoms of prostate disease.

Calcium channel blockers

Calcium channel blockers block the entry of calcium into muscle cells in artery walls.

• dihydropyridines:
  • amlodipine
  • felodipine
  • isradipine
  • nifedipine
  • nimodipine
  • nitrendipine
• non-dihydropyridines:
  • diltiazem
  • verapamil

ACE inhibitors

ACE inhibitors inhibit the activity of Angiotensin-converting enzyme (ACE), an enzyme responsible for the conversion of angiotensin I into angiotensin II, a potent vasoconstrictor.

• captopril
• enalapril
• fosinopril
• lisinopril
• perindopril
• quinapril
• ramipril
• trandopril
• benzapril

Angiotensin II receptor antagonists

Angiotensin II receptor antagonists work by antagonizing the activation of angiotensin receptors.

• candesartan
• irbesartan
• losartan
• telmisartan
• valsartan

Aldosterone antagonists

Aldosterone antagonists:

• spironolactone

Aldosterone antagonists are not recommended as first-line agents for blood pressure, but spironolactone is useful in the treatment of heart failure.

Vasodilators

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them; they are only used in emergencies.

• sodium nitroprusside

Centraly acting adrenergic drugs

• Clonidine
• Guanabenz
• Methyl-dopa

Adrenergic neuron blockers

• Guanethidine
• Reserpine

Herbals provoking hypotension

• Agrimony
• Celery
• Cornsilk
• Garlic
• Ginger
• Ginseng
• Golgenseal
• Hawthorn
• Mistletoe
• Nettle
• Parsley
• Pokeroot
• Sage
• Squill
• Wild Carrot

Choice

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The choice between the drugs is to a large degree determined by the characteristics of the patient being prescribed for, the drugs' side-effects, and cost. For example, asthmatics have been reported to have worsening symptoms when using beta blockers. Most drugs have other uses; sometimes the presence of other symptoms can warrant the use of one particular antihypertensive (such as beta blockers in case of tremor and nervousness, and alpha blockers in case of benign prostatic hyperplasia). The JNC 7 report outlines compelling reasons to choose one drug over the others for certain individual patients.

References

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1. Herbals Affecting Blood Pressure Provoking Hypotension; Clark (2003) AAFP Board Review, Seattle

See also

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• arterial hypertension

Antihypertensive agents

Antihypertonikum | Antihipertenzív szerek | Blodtrykkssenkjande lækjemiddel | Antihipertensivo | ยาลดความดัน