Types of Drugs
This section contains information on:
¨ ACE Inhibitors
¨ Anti-arrhythmic
drugs
¨ Anticoagulants
¨ Aspirin (and other
anti-platelet drugs)
¨ Beta-Blockers
¨ Calcium channel
blockers (calcium antagonists)
¨ Cholesterol
(lipid) - lowering drugs
¨ Diuretics
¨ Potassium channel
activators
¨ Thrombolytic drugs ('clot busters')
¨ Other drugs used
for high blood pressure
ACE Inhibitors
These drugs are very effective in treating and preventing
heart failure. They are recommended for most patients with
heart failure and are also used to lower high blood pressure.
Also, after a heart attack, many patients will benefit from
an ACE inhibitor.
ACE stands for 'angiotensin converting enzyme'. Angiotensin
is a chemical which has a powerful narrowing effect on the
blood vessels. It is produced as a result of the actions of
another chemical called angiotensin converting enzyme (ACE).
The activity of this substance can be reduced by angiotensin
converting enzyme inhibitors (ACE inhibitors).
Unwanted Effects
ACE inhibitors are generally better tolerated by patients
than most other drugs used for similar purposes. However,
they can cause a marked fall in blood pressure, especially
when first used by people who are also taking diuretics.
They may also affect the function of the kidneys if this
is already abnormal. When your doctor starts the treatment,
he or she will take care to start you on a low dose and will
regularly check your blood pressure. Your kidney function
will be checked at least once, by taking a blood test.
Some ACE inhibitors may affect your sense of taste and cause
skin rashes and, very occasionally, a major allergic reaction.
Some people develop a persistent, dry, irritating cough. If
this happens, you should tell your doctor about it.
Some Examples are: Ramipril (Tritace)
Perindopril (Coversyl)
Lisinopril (Carace)
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Anti-Arrhythmic Drugs
'Anti-arrhythmic' drugs are for controlling the rhythm of
the heart. Beta-blockers and the calcium antagonist Verapamil
are often used to treat disturbances of the heart rhythm (arrhythmias),
but there are several other drugs that are used almost exclusively
for this purpose.
Amiodarone
Amiodarone is very effective in controlling disturbances
of the heart rhythm. At low doses it is well tolerated, but
has important side effects. It may produce headache, flushing,
dizziness and stomach upsets. More seriously, and more rarely,
it may cause disorders of the thyroid gland, lungs and liver.
To avoid these complications, periodic blood tests are carried
out. You may also have chest x-rays and tests of your lung
function.
A slaty blue discoloration of the skin may develop when you
are exposed to sunlight. If you are taking Amiodarone you
should use a powerful sunscreen cream when you are in bright
sunshine, and wear a hat.
Flecainide
This is an anti-arrhythmic drug that may be used for a variety
of heart rhythm disturbances such as atrial tachycardias and
ectopic beats
Propafenone
This is an anti-arrhythmic drug that is used to treat various
arrhythmias such as intermittent or 'paroxysmal' atrial fibrillation.
It is usually avoided in patients who have asthma or chronic
lung disease.
Digoxin
Digoxin is often used to treat atrial fibrillation, a common
heart rhythm disorder. In this arrhythmia, the heart beats
fast and irregularly, and may lead to heart failure. Digoxin
slows the heart but does not restore its regularity. This
may be enough to relieve the symptoms of breathlessness and
palpitation, but additional treatment may be required to return
the heartbeat to normal.
Digoxin and similar drugs derived from the foxglove plant
(digitalis) have been in use for two centuries in the treatment
of heart failure.
Unwanted Effects
Digoxin may cause loss of appetite and nausea. Less frequently
it can cause vomiting, painful or enlarged breasts, rash,
palpitation, and fainting. You should tell your doctor if
you get any of these symptoms, as it may be necessary to adjust
the dosage.
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Anticoagulants
Clots consists of two elements - platelets (small blood cells)
clumped together, and a protein called fibrin. Anticoagulants
prevent fibrin from forming but, in doing so, they may cause
or aggravate bleeding.
Heparin is usually given intravenously when the prevention
of further clotting is considered urgent. A more recently
developed form of heparin (low molecular weight heparin) may
be given subcutaneously (by injections) over a longer period.
Warfarin or other oral anticoagulants are given when long-term
prevention of clotting is required. These drugs are most often
used for patients with diseases of the heart valves, especially
those who have been given an artificial heart valve, or for
some people with an irregular heart rhythm.
Anticoagulants are also of particular value in treating clots
in the veins of the legs (deep vein thrombosis) and in preventing
these clots from travelling through the blood to the lungs
(pulmonary embolism).
Because of the effects of these drugs on bleeding, regular
blood tests are needed to make sure that the reduction of
the clotting activity of the blood is within safe but effective
levels. At the start, these tests may be undertaken almost
every day but later they will be done only every 6-8 weeks.
If you are taking oral anticoagulants, you should check with
your doctor or pharmacist before taking any other drugs -
both over-the-counter drugs and prescription drugs. This is
because oral anticoagulants interact with many medicines including
antibiotics, aspirin, Cimetadine (Tagamet), and with some
drugs that are used to treat arthritis, gout, epilepsy, high
blood cholesterol, and disorders of heart rhythm.
Patients receiving anticoagulants should always carry an
Anticoagulant Card and remember to inform doctors and nurses
about their anticoagulant treatment.
Any of the following symptoms might indicate that your dose
of anticoagulants is too high:
¨ Prolonged bleeding from cuts
¨ Bleeding that does not stop by itself
¨ Nose bleeds that last for more than a few minutes
¨ Bleeding gums
¨ Red or dark brown urine
¨ Red or black stools, or
¨ For women, heavier bleeding during periods, or other
vaginal bleeding
If you are worried, contact your anticoagulant clinic or
the casualty department at your local hospital. Make sure
that you have your dosage record card and any other medication
with you.
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Aspirin (and other anti-platelet
drugs)
Aspirin has been used for pain relief for more than a hundred
years, but it is also effective in preventing the clotting
of blood. It achieves this by reducing the 'stickiness' of
platelets - the small blood cells that can clump together
to form a clot. The dose needed for this effect is smaller
than the dose needed to relieve a headache.
Aspirin reduces the risk of dying after a heart attack, and
the risk of a further heart attack and stroke in those who
have already suffered from one of these disorders. It is also
useful for patients with angina, and is used to prevent blood
clotting in the vein grafts used in coronary artery bypass
surgery. It is therefore used almost routinely for treating
patients with known coronary heart disease , unless these
are strong reasons for not giving it.
Other anti-platelet drugs such as Clopidogrel and Ticlopidine,
have recently been developed. Clopidogrel (Plavix) can be
used around the time of angioplasty to reduce the risk of
blood clotting and is used frequently in combination with
aspirin after unstable angina or a heart attack. (Other drugs,
called glycoprotein IIb/IIIa receptor inhibitors (Reopro),
can be given by intravenous injection to prevent clotting
in unstable angina or at the time of coronary angioplasty).
Unwanted Effects
Aspirin can cause indigestion, nausea, vomiting, and constipation.
The stomach problems may be overcome by using special preparations
of the drug. More seriously, Aspirin can provoke or worsen
bleeding from the stomach. This is less of a problem with
Clopidogrel. Occasionally, it can precipitate and asthma attack.
These harmful effects are very uncommon, but because of them
Aspirin is not recommended as a way to prevent heart attacks
or strokes in healthy people with no other risk factors
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Beta Blockers
Beta-blockers block the actions of hormones such as adrenaline
that make the heart beat faster and more vigorously. They
prevent the heart from beating as quickly and forcefully as
usual on exercise and emotion. Beta-blockers are very effective
in preventing attacks of angina but they work too slowly to
be useful in relieving an attack of angina. They are also
effective in lowering raised blood pressure and in reducing
the risk of a further heart attack in people who have already
had one. Some beta-blockers can help control abnormal heart
rhythms.
The disadvantages of beta-blockers include a tendency to
constrict the air passages (bronchi). For this reason, they
should be avoided in people who suffer from asthma or wheezing.
They may also constrict small blood vessels, which can cause
cold hands and feet.
In diabetic people who are taking medication for their diabetes,
beta-blockers may mask the symptoms of too low a blood sugar
level.
Because beta-blockers reduce the force of the heartbeat,
they need to be used with care in people with heart failure.
However, some patients with heart failure do benefit from
beta-blockers.
Many preparations of beta-blockers are available, but they
differ from one another only slightly. So called 'selective'
beta-blockers have less adverse effects on the lungs and are
less likely to mask the symptoms caused by a low blood sugar
level.
Unwanted Effects
Serious side effects are rare if beta-blockers are used with
care. However, minor side effects are common and include tiredness,
fatigue, and cold hands and feet. Other less frequent adverse
effects include nausea, diarrhoea, skin rashes, impotence
or other sexual disorders, nightmares and pins and needles
in the fingers.
Beta-blockers should not be stopped suddenly without medical
advice as coming off them too quickly can make angina worse.
Examples:
¨ Atenolol
¨ Metoprolol
¨ Bisoprolol
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Calcium Channel Blockers (Calcium Antagonists)
A regular inflow of calcium is essential for the normal functioning
of muscle cells in the heart and elsewhere. Calcium antagonists
reduce the amount of calcium entering the muscle cells of
the arteries (including the coronary arteries) and cause them
to relax. They therefore have the effect of increasing the
blood supply to the heart and reducing the work the heart
has to do to pump blood around the circulation.
Some (such as Nifedipine) increase the heart rate at rest.
Others (such as Diltiazem and Verapamil) tend to reduce the
natural increase in heart rate, which usually occurs when
you exercise. Because of this, the combination of Nifedipine
and beta-blockers may be effective, whereas there is a danger
that the heart rate may become too slow if beta-blockers are
combined with Diltiazem or Verapamil.
Calcium channel blockers are sometimes used in the treatment
of angina, often together with other drugs. They are also
used to reduce high blood pressure.
Unwanted Effects
Serious side effects are uncommon. Minor adverse effects
include flushing, headache, dizziness, faintness, swelling
of the ankles, and a variety of gastro-intestinal disturbances
('Gastro-Intestinal' means of the stomach or intestine). Verapamil
can cause troublesome constipation.
Examples:
¨ Amlodipine (Istin)
¨ Diltiazem (Tildiem)
¨ Nifedipine (Adalat)
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Cholesterol (Lipid) - Lowering Drugs
'Blood lipid' is the name given to all the fatty substances
in the blood, including HDL cholesterol, LDL cholesterol and
triglycerides. The overall aim of diet and drug treatment
for high blood cholesterol is to lower the total amount of
cholesterol in the blood, and particularly to lower the amount
of LDL cholesterol.
The main types of drugs now used to reduce cholesterol levels
are statins. These can reduce LDL cholesterol levels by more
than 40%. Before starting statins, you may have a blood test
to assess your liver function. This test will be repeated
while you are having treatment.
Examples:
¨ Simvastatin (Zocor)
¨ Pravastatin (Lipostat)
¨ Atorvastatin (Lipitor)
Statins are not suitable for people who have liver disease
or who are pregnant or breastfeeding. There are two other
types of drugs that can be used when statins are not suitable.
These are drugs, which bind bile acids, and the fibrates.
Fibrates are also used for people who have a high level of
both blood cholesterol and triglycerides.
Examples:
¨ Fenofibrate (Supralip)
¨ Ezetrol (Ezetimibe)
Unwanted Effects
A rare side effect of statins is inflammation of the muscles
(myositis). You should tell your doctor if you have any unexpected
muscle pains, tenderness or weakness.
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Diuretics
Diuretics, or water tables, increase the output of water
and salt in the urine. They are particularly valuable in the
treatment of heart failure, in which there is an excess of
water and salt in the body. Diuretics are also effective in
lowering high blood pressure.
There are 3 main types of diuretic: Thiazide, Loop diuretics
and potassium sparing diuretics. Thiazide and loop diuretics
can cause you to lose potassium, so your doctor will arrange
a blood test a few weeks after starting to check the potassium
level in your blood. If this is getting low, you will be given
potassium supplements, or a potassium sparing diuretic instead.
This usually corrects the imbalance. In the treatment
of heart failure, diuretics are often combined with Digoxin
and/or ACE inhibitors. In high blood pressure, they may be
used alone or in combination with beta-blockers, calcium channel
blockers, ACE inhibitors, or other drugs.
If you are taking diuretics you should not take too much salt
in your food as this counteracts the effects of the diuretics.
Don’t add any salt to food during cooking or the table,
and avoid salty foods.
Unwanted Effects
Some diuretics may cause low potassium levels. Therefore,
if you are taking diuretics you may need to have tests from
time to time to check on the levels of various chemicals in
your blood. People with diabetes may find that diuretics raise
their blood sugar levels. People with gout may find that diuretics
worsen their condition.
Examples:
¨ Frusemide
¨ Bumetanide
¨ Bendrofluazide
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Nitrates
Nitrates relax the muscles in the walls of the veins and arteries
(including the coronary arteries) and make them wider. They
are very useful in relieving angina pain and in preventing
'predictable' attacks. (For example if taken just before doing
something that usually brings on an angina attack). They are
also of value in the long-term prevention of angina, but they
may become less effective if they are used continuously over
a long period.
Glyceryl Trinitrate Tablets
Also called GTN, Trinitrate or Nitroglycerin tablets. Tablets
of glyceryl trinitrate, put under the tongue relieve angina
quickly. They are particularly effective when used to prevent
a predictable attack.
You should let the tablets dissolve under your tongue. They
are ineffective if you swallow them. The tablets lose their
strength quite quickly and should be replaced with a fresh
supply after 6-8 weeks.
You may get a throbbing headache when you first take these
tablets, but after you have been taking them for a while this
side effect usually disappears. They may also cause flushing,
dizziness or even fainting, so it is beset to sit down when
taking your first tablet.
Aerosol Spray
Glyceryl Trinitrate can be given in an aerosol spray. You
need to spray 2 doses on or under you tongue. There is no
need to shake the canister before spraying.
Oral Nitrates
Isosorbide Mononitrate and Dinitrate are effective drugs in
preventing angina. If you find that the tablets become less
effective, tell your GP.
Example:
¨ ISMN (Imdur)
Nitroglycerin skin patch
Self-adhesive skin patches containing nitroglycerin are effective
in preventing angina, but they may become less effective if
they are used continuously for a 24 hour period. It may therefore
be helpful to leave the patches off for several hours in each
24 hour period.
Unwanted Effects
Headache, flushing, dizziness and faintness can occur with
nitrates, but are most common with glyceryl trinitrate tablets.
These symptoms tend to lessen with continued use.
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Potassium Channel Activators
Potassium channel activators are a new type of drug given
to relieve angina. They have a similar effect to nitrates
as they relax the walls of the coronary arteries and therefore
improve blood flow. Unlike nitrates, they do not appear to
become less effective with continued use.
Example:
¨ Nicorandil (Ikorel)
Unwanted Effects
Unwanted effects of potassium channel activators may include
initial headache, flushing, indigestion or dizziness.
Thrombolytic Drugs ('clot busters')
These drugs are used only when there is an urgent need to
dissolve a clot. This is most often for a heart attack. The
sooner they are given after beginning of the attack, the better.
The most commonly used drug is Streptokinase, given directly
into a vein. Some hospitals use newer drugs such as TPA which
maybe slightly more effective. Thrombolytic drugs may cause
serious bleeding, so before they are given the doctor must
be reasonably sure of the diagnosis and that the patient does
not have a high risk of bleeding (for example if the person
has recently had surgery).
If you receive thrombolytic drugs, you should be given a card
to carry with you, describing the type of thrombolytic drug
given and when it was given. If the thrombolytic was Streptokinase
or Anistreplase, you should not have a repeat dose for several
years. If another heart attack occurs, a different thrombolytic
drug can be given (TPA).
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Other Drugs used for high blood
pressure
High blood pressure can usually be controlled successfully
with one or more of the drugs mentioned above - diuretics,
beta-blockers, calcium channel blockers, and ACE inhibitors.
Sometimes these are not enough, or may have unacceptable side
effects, and other drugs are added or given instead.
Among these are: alpha-blockers, angiotensin II antagonists,
Methyldopa and Moxonidine. These are described next.
Alpha-blockers such as Prazosin, Doxazosin, and Terazosin
These may cause a large fall in blood pressure when they are
first used. They can also cause tiredness.
Angiotensin II Antagonists
These act in a similar way to ACE inhibitors but do not cause
the persistent dry cough that ACE inhibitors can sometimes
cause. They are therefore a useful alternative to ACE inhibitors.
Examples:
¨ Irbesartan
¨ Losartan
Methyldopa
This is used, with diuretics, to reduce blood pressure. It
can cause dry mouth, and also drowsiness that can interfere
with skilled tasks including driving.
Moxonidine
This is a blood pressure lowering drug, which may be prescribed
if other drugs are not suitable or have failed to control
high blood pressure.
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