Anti-hypertensive therapy

They are very numerous and are composed of various classes of drugs. They are effective for the fall of the blood pressure. On average, the maximum blood pressure (systolic) decreases by 15 to 20 millimetres of mercury and the minimal blood pressure (diastolic) decreases from 5 to 10 millimetres of mercury.

Nevertheless, the effect on the fall of the blood pressure is similar between all these drugs.
The blood pressure is defined as the product of the resistance of the vessel (artery) and the cardiac output:

6.5.1- A reduction of the cardiac output is responsible for an arterial pressure decrease.

The drugs responsible for a cardiac output reduction are called beta-adrenoreceptor blocking drugs; these drugs are very effective in reducing the blood pressure and have, moreover, a protective effect on the heart.

Their principle is to decrease the cardiac output by decreasing the frequency of the heart. Thus, these drugs must be supervised regularly because they slow down the heart rate in a very significant way.

They are excellent products for the patients who have had a myocardial infarction or who present an angina pectoris. Nevertheless, they are contra-indicated in the case of a very low heart rate, of cardiac insufficiency, asthma, chronic bronchiolitis obliterans and in the case of a dead hand.

Their undesirable side-effects are represented by a tiredness, a cooling of the limbs, digestive disorders, impotence, insomnia and nightmares. It is very important not to stop this treatment suddenly. Generally, only one tablet per day is prescribed, in the morning.

Principal beta-blockers are: the atenolol, the acebutalol, the propranolol, the celiprolol, the metoprolol, the pindolol, the nadolol, the carteolol, the esmolol, the timolol, the penbutolol, the bisoprolol, and the betaxolol.

6.5.2- The relaxation of the peripheral artery involves a blood pressure decrease

- By acting directly on the muscles of the artery: the calcium antagonist therapy

These drugs, still called calcium blocker or calcium channel antagonist, are frequently employed because of their low number of counter-indications. Their undesirable side-effects consist of oedemas of the lower limbs (especially ankles), headaches and hot flushes.

The principal calcium antagonist therapies in France are: the nifedipine, the nitrendipine, the diltiazem, the lacipidine, the félodipine, the amlodipine, the nicardipine, the verapamil, and the bépridil.

- the inhibition of the receptors of some substances involving a contraction of the artery is also a way to decrease the resistance of the artery

* Among these products, the converting enzyme inhibitors or the angiotensin-converting enzyme inhibitor

These drugs will go against the synthesis of a vasocontracting substance by the kidney: the angiotensin.

These drugs are particularly adapted for the subjects who have had a myocardial infarction, a cardiac insufficiency or a disease of the kidney without severe renal insufficiency.

They are generally very well tolerated and their principal undesirable side-effect is a dry cough. They are contra-indicated in the event of an allergic history when these drugs, in case of a pregnancy and of a severe renal insufficiency, as well as an obstruction of the flow in the renal arteries.

The principal drugs of the converting enzyme inhibitors are: the captopril, the quinapril, the bénazépril, the périndopril, the fosinopril, the trandolapril, the quinapril, the lisinopril, the cilazapril and the moexipril.

These drugs avoid stopping the production of angiotensin which is a hormone secreted by the kidney and involves a contraction of the peripheral arteries.

These drugs are generally well tolerated and their counter-indications are essentially pregnancy or an obstruction in the kidney’s arteries.

The principal drugs of this family in France are: The irbésartan, the candesartan, the losartan, the valsartan and the telmisartan.

* Some drugs will avoid the adrenalin effect on the artery: the alpha-adrenergic receptor antagonists.

The fixation of the adrenalin on the receptor alpha induces a contraction of the peripheral arteries. The alpha-adrenergic receptor antagonists drugs will limit its action and thus induce an arterial pressure decrease.

Their principal side-effect is a postural hypotension that generally occurs during the move from the lying position to the standing position. Other side-effects: weakness, fatigue and headaches.

The principal drugs are represented in France by: the prazosine, the urapidil and the minoxidil.

The diuretics help the removal of sodium and of water from the body, induce a dilation of the peripheral arteries and contribute to the decrease of the arterial blood pressure.

These drugs are often associated with other kinds of anti-hypertensive drugs because of their excellent synergism.

Their principal side-effects are a fatigue, impotence and the frequent emission of urine, this last effect being reduced by the existence of drugs with lighter doses, but quite as effective.
The principal diuretic drugs in France are: the hydrochlorothiazide, the indapamide.

A special diuretic: the soludactone. This drug is not only diuretic, but it reduces the synthesis of the aldactone produced by the suprarenals glands, which involves a contraction of the artery.

Its side-effects are impotence, irregular periods in women and the appearance of " breasts " in men (galactorrhea).

Many drugs will reduce the blood pressure by acting directly on the cerebral receptor, which controls the blood pressure: these drugs are called central alpha agonist.

Their principal side-effects consist of: somnolence, sedation, dry mouth, impotence and galactorrhea.

If a stop of this treatment is necessary, the decrease have to be progressive until the stop. The principal drugs are: Methyldopa, the clonidine, the minoxidine, the guanabenz and the guanfacine.