What to do in case of a high blood pressure
- First of all, to eliminate a false high blood pressure
- To eliminate an obvious cause responsible for a high blood pressure
- To start a treatment without drug: life style modifications
6.4 - According to
the circumstances, to treat by using drugs
6.5 - Anti-hypertensive therapy
- Why does the doctor prescribe a given anti-hypertensive drug and not
another? The choice of the first treatment.
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
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:
pressure = Resistance of artery x cardiac output.
Thus, the antihypertensive
drug therapy will act on these two components:
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
There are several ways to
relax the artery so as to decrease its resistance:
- 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
* Another category: Angiotensine
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 kidneys 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.
* Another family of antihypertensive
drugs: the diuretics.
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
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
6.5.3- Drugs that act
on the cerebral receptor
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.
last reviewed on : 18 dec 2011