There are five main classes of medicines that are used to lower blood
pressure. There are various types and brands of medicine in each class.
The following gives a brief overview of each of the classes. However,
for detailed information about your own medication you should read the
leaflet that comes inside the medicine packet.
Angiotensin-converting enzyme (ACE) inhibitors
ACE inhibitors
work by reducing the amount of a chemical that you make in your
bloodstream, called angiotensin II. This chemical tends to narrow
(constrict) blood vessels. Therefore, less of this chemical causes the
blood vessels to relax and widen, and so the pressure of blood within
the blood vessels is reduced.
There are various types and brands of ACE inhibitors:
captopril,
cilazapril,
enalapril,
fosinopril,
lisinopril,
perindopril,
quinapril,
ramipril, and
trandolapril. An ACE inhibitor is particularly useful if you also have
heart failure or
diabetes.
ACE inhibitors should not be taken by people with certain types of
kidney problems, people with some types of artery problems, and those
who are pregnant. You will need a blood test before starting an ACE
inhibitor. This will check that your kidneys are working well. The blood
test is repeated within two weeks after starting the medicine, and
within two weeks after any increase in dose. Then, a yearly blood test
is usual.
Angiotensin receptor blockers
These medicines are sometimes called angiotensin-II receptor antagonists. There are various types and brands:
candesartan,
eprosartan,
irbesartan,
losartan,
olmesartan,
telmisartan and
valsartan.
They work by blocking the effect of angiotensin II on the blood vessel
walls. So, they have a similar effect to ACE inhibitors (described
above).
Calcium-channel blockers
Calcium-channel blockers
affect the way calcium is used in the blood vessels and heart muscle.
This has a relaxing effect on the blood vessels. Again, there are
various types and brands:
amlodipine,
diltiazem,
felodipine,
lacidipine,
lercanidipine,
nicardipine,
nifedipine, and
verapamil. Calcium-channel blockers can also be used to treat
angina.
'Water' tablets (diuretics)
Diuretics work by increasing the amount of salt and fluid that you
pass out in your urine. This has some effect on reducing the fluid in
the circulation, which reduces blood pressure. They may also have a
relaxing effect on the blood vessels, which reduces the pressure within
the blood vessels. The most commonly used diuretics to treat high blood
pressure (hypertension) in the UK are
thiazides or thiazide-like diuretics. Examples are
bendroflumethiazide,
chlortalidone,
cyclopenthiazide, and
indapamide.
Only a low dose of a diuretic is needed to treat high blood pressure.
Therefore, you will not notice much diuretic effect (that is, you will
not pass much extra urine). You will need a blood test before starting a
diuretic, to check that your kidneys are working well. You should also
have a blood test within 4-6 weeks of starting treatment with a
diuretic, to check that your blood potassium has not been affected.
Then, a yearly blood test is usual.
Beta-blockers
Again, there are various types and brands of
beta-blockers:
acebutolol,
atenolol,
bisoprolol,
metoprolol,
oxprenolol,
pindolol, propranolol,
sotalol, and
timolol.
They work by slowing the heart rate, and reducing the force of the
heart. These actions lower the blood pressure. Beta-blockers are also
commonly used to treat angina, and some other conditions. You should not
normally take a beta-blocker if you have asthma, chronic obstructive
pulmonary disease (COPD), or certain types of heart or blood vessel
problems.
