EEMY Greek English
 

41 PRACTICAL QUESTIONS AND ANSWERS ABOUT HYPERTENSION AND HYPERCHOLESTEROLEMIA - 2008

DRUG TREATMENT FOR HYPERTENSION PREVIOUS QUESTION  QUESTIONS  NEXT QUESTION
  • Antihypertensive drugs are probably the most widely researched drugs currently in use. Numerous studies involving several thousands of hypertensive persons who have been under observation for years have shown that -at least- the 5 groups of first choice drugs (see above) are highly effective not only in lowering blood pressure but also in the protection of the organs which are damaged by high blood pressure. Furthermore, they have few side effects which are rarely severe. Drugs with frequent or severe side effects have already been withdrawn from the market.

Diuretics (thiazides)

  • Diuretic drugs initially act by augmenting the urine production and by diminishing salt and water retention and reducing thereby circulating blood volume. When used daily over a long period of time, they no longer induce increased urine production, but they lower the resistance of the arteries.
  • They can be used as a single drug for treating hypertension (monotherapy), but they are mainly very useful in cases when the combination of two drugs is required. In such cases, a fixed combination of the two drugs may already be available in the market.
  • Their most common side effect is the decrease of potassium level in the blood. In few cases, they can also induce the increase in blood uric acid and glucose, as well as the decrease in sodium, mainly when they are used in higher doses.

Beta-blockers (b-blockers)

  • Beta-blockers reduce the effect of a vasoconstricting substance, named noradrenalin, by blocking its site of action (the beta receptors). They also slow down the heart rate (i.e. they induce bradycardia) and reduce the cardiac output.
  • They are useful in treating hypertension and are especially recommended when a patient's history includes one or more of the following: myocardial infarction, angina (i.e. chest pain due to insufficient blood flow to the heart), heart failure and arrhythmia.
  • Their most common side effects are the feeling of fatigue, bradycardia (below 50 beats per minute) and bronchospasm (causing dyspnea) in patients with asthma or chronic obstructive pulmonary disease.

Calcium channel blockers (calcium antagonists)

  • Calcium channel blockers prevent the entry of calcium ions into the muscle cells of the arterial vessel walls and this results in vasodilatation. There are two different types of calcium channel blockers: the dihydropyridines and the non-dihydropyridines (bradycardic calcium channel blockers)
  • They are useful in treating hypertension, especially in persons with angina (i.e. chest pain due to ischemia of the heart). Non-dihydropyridines (bradycardic calcium channel blockers) are especially useful in treating hypertension in persons with arrhythmia.
  • Their most common side effects are edema (swelling) of the lower limbs (especially of the ankles). Edema is caused by local vasodilatation (arterial dilatation) and does not carry any danger. The use of diuretics is not useful in treating this type of edema which easily responds to drug withdrawal or to dose reduction. Dihydropyridines may also rarely cause a facial rash, headaches or tachycardia whereas non-dihydropyridines may cause constipation, headaches or bradycardia.

Angiotensin converting enzyme inhibitors (ACE inhibitors)

  • Angiotensin converting enzyme inhibitors inhibit the formation of a vasoactive substance called angiotensin. Angiotensin induces the contraction of arteries as well as the secretion of another substance called aldosterone, which increases sodium (salt) and water retention by the kidneys.
  • They are useful in treating hypertension especially in persons with heart failure, previous myocardial infarction or renal disease due to diabetes mellitus.
  • Their most common side effect is a consistent dry cough. In rare cases of bilateral renal artery stenosis they may cause a deterioration of renal function.

Angiotensin receptor blockers (ARBs)

  • Angiotensin receptor blockers inhibit the action of the substance angiotensin (see above "Angiotensin converting enzyme inhibitors") on its specific site of action (which is called AT1 receptors). This results in vasodilatation and reduction of the sodium (salt) and water retention by the kidneys.
  • They are useful in treating hypertension especially in patients with heart failure or hypertrophy of the left ventricle, with a history of myocardial infarction, or of renal disease due to diabetes mellitus.
  • Side effects are rare. Like angiotensin converting enzyme inhibitors in the rare cases of bilateral renal artery stenosis they may cause a deterioration of renal function.

Alpha 1-blockers (a-blockers)

  • The alpha 1-blockers inhibit the action of the substance called noradrenaline by blocking its specific receptors (a1 receptors) which are located on the vascular walls.
  • They are used in treating hypertension as well as in symptomatic prostate hypertrophy.
  • They may cause a feeling of fatigue as well as an exaggerated decrease of blood pressure when used for the first time (first dose effect).

Alpha 2-agonists and I1- blockers

  • They act on specific sites in the brain (receptors a2 and I1, respectively) and thus reduce the activity of the vasoconstrictive system that uses the two substances adrenaline and noradrenaline as mediators.
  • These drugs are used only for the treatment of hypertension. One of these drugs, called methyldopa, is the safest and most commonly used drug for treating hypertension that develops during pregnancy. Their main adverse reactions are drowsiness and dry mouth (xerostomia). Methyldopa may also cause anemia or liver dysfunction.

Directly acting vasodilators

  • They act directly on the arterial wall causing vasodilatation.
  • They are used rarely, mainly in cases of difficult-to-control hypertension in combination with other drugs. Their main side effects are palpitations, hirsutism and the reduction of renal function.

WRITING GROUP
G. Stergiou, Chairman
A. Achimastos
E. Andreadis
I. Avramopoulos
M. Elissaf
N. Karatzas
T. Mountokalakis
D. Papadogiannis
K. Siamopoulos
E. Varsamis
K. Vemmos
D. Vlahakos