Drugs for the heart Disease
A wide variety of drugs are
prescribed for the treatment of patients with coronary heart disease. They are
used to treat conditions such as angina, heart failure, hypertension,
arrhythmias etc. Since most forms of heart disease are chronic, drug treatment
is generally long term. These drugs are effective in reducing sufferings and
prolonging life. But drugs are associated with some side effects and the
response to a drug may also vary from individual to individual so that the
doctor who prescribes the medication may modify the dose to suit each patient’s
particular circumstances.
The most important drugs used in
coronary heart disease include:
1. Antiplatelets e.g.
Aspirin, ticlopidine, dipyridamole, clopidogrel etc.
1. Antiplatelet drugs: The platelets are tiny blood cells
that have an important function in the blood clot formation. When a blood
vessel is injured, the platelets stick to the vessel wall and to each other,
thus forming a cot at the damaged site. In patients with coronary heart
disease, for example, there is an increased tendency for blood clots to form at
the site of a partial blockage, leading to complete blockage of the coronary
artery resulting in a myocardial infarction or heart attack. Antiplatelet drugs reduce the stickiness of the blood cells like platelets and therefore the
tendency for blood clot formation. Antiplatelet agents are prescribed to reduce
the risk of heart attack in patients who have angina, those who already have
suffered a heart attack, in patients after by pass operation and after balloon
angioplasty. Aspirin is the most widely prescribed antiplatelet drug. Low dose
aspirin 57 mg to 325 mg once daily after meal may be prescribed. This drug may
produce gastric irritation of aggravate peptic ulcer. In this circumstance the patient
may produce gastric irritation or drug along with tablet ranitidine or
famotidine. It is recommended that all patients after heart attack should
continue aspirin in dos 160 to 325 mg per day if not associated with
significant side effects. If the patient cannot tolerate aspirin, ticlopidine
is a good alternative. Ticlopidine in dose 250 mg twice daily is generally
recommended. Dipyridamole is usually used along with aspirin, not usually as a
single medicine.
2. Bata-blockers: Beta-blockers remain a cornerstone
in the treatment of coronary heart disease. In many studies it has been found
that these drugs decrease the incidence of recurrent heart attack and sudden
death. This group of medicines has at least triple action for patients with
ischaemic heart disease, anti ischaemic antiarrhythmic and antihypertensive.
Coronary used beta blockers are atenelol, propranolol, metoprolol, carvedilol.
Early use of beta blockers can reduce death by 13-15% after heart attack. Beta-
blockers heart attack trial has documented that beta-blockers can reduce long term mortality by 28%. Beta blockers atenolol 25 mg to 100 mg per day or
propranolol 20 mg three times daily to 80 mg three times daily are commonly
prescribed. This drug should be given to all patients with heart attack except
the patients with heart failure, asthma, low blood pressure, bradycardia, heart
block etc. All patients with coronary heart disease may continue this drug
indefinitely.
3. Nitrates: The commonly used nitrates are
glyceryl trinitrate (GTN) isosorbide dinitrate and isosorbide mononitrate.
Nitrates increase the oxygen supply by dilating the coronary arteries and
decrease the oxygen demand of the heart. GTN under tongue or spray are widely
used for instantaneous relief of anginal pain. These drugs are also available
as injection. GTN may also be used as skin patch e.g. nitro-dur, nirodisc,
transiderm nitro, deponit etc. Continuous administration of nitrates may
produce nitrate tolerance. To avoid this, blood should be kept nitrate free for
about 4-8 hours. Eccentric twice daily doses spaced by 7 hours or once daily
dose of extended release formulation of mononitrate e.g. indur or avoiding the
evening dose on holiday may reduce the chance of nitrate tolerance. The maximum
dose of isosorbide dimitrate is 120 mg per day in divided doses and isosorbide
mononitrate 80-120 mg per day according to patient's response.
4. Calcium channel
blockers: Calcium
channel blockers nifedipine and verapamil have antianginal, vasodilatory and
antihypertensive properties. But they do not reduce mortality during and after
heart attack and are not recommended as standard therapy. In most of the
studies these drugs have revealed no evidence of harm or benefit for patients
with heart attack. But amlodipine or dilitiazem may be used to control
concurrent high blood pressure.
5. ACE Inhibitors: Angiotensin convertion enzye
inhibitors (ACEI) reduce left ventricular dysfunction and slow the progression
to heart failure. The most commonly used drugs are captopril, lisinopril,
enalapril, ramipril. Most of the studies consistently shown reductions in
mortality in patients of heart attack treated soon after the attack. Lisionopril
2.5 mg to 20 mg once daily or captopril 6.25 mg to 50 mg twice daily or
enalapril 5 mg to 20 mg once or two divided doses are essential for patients
with heart attack. In ISIS study captopril reduced mortality by 7% and in
GISSI-3 study lisinopril reduced the mortality by 12%. In all patients with
acute myocardial infarction except specific contraindications, ACE inhibitors
should be given within 24 hours after the onset of pain and the drug should be
continued probably indefinitely. Some patient can not tolerate this group of
medicine due to dry iffitating cough. This side effects some times take a long
time to be discovered. In some centers, the incidence of cough is thought to be
as high as 10%-15%, whereas others report a much lower incidence. ACE inhibitors like acepril, zestril,
neopril. Anapril, cardace, coversyl are effective in all patients after heart
attack but they may produce some side effects that cause concern. A persistent
troublesome dry cough is an important side effect of conventional ACE inhibitors.
New drugs, angiotensin receptor blockers like valsartan and losartan are
effective for cardiac protection after heart attack. These new drugs do not
produce cough.
6. Diuretics: These drugs are usually used for
heart failure and control of hypertension. The most commonly used drug for
heart failure is frusemide. This medicine can be used as injection in the
treatment of severe heart failure.
7. Cholesterol lowering
drugs:
Lowering the cholesterol level below the target level after heart attack is a
prime concern. All treatments will go in vain if cholesterol level remains
uncontrolled. The target LDL cholesterol concentration is less than 160 mg/dl
for patients with no risk factor, less than 130 mg/dl for patients with two or
more coronary risk factors and less than 100 mg/dl for those with coronary
artery disease, angina or after heart attack. Most of the clinical trials have
found that drug treatment for high cholesterol reduces the incidence of
angina/heart attack by 25 to 60% and reduce the risk of death from any cause by
about 30%. Liver toxicity occurs in less than 1% of patients given very high
doses and it is very rare during treatment with low doses. These drugs can be
continued for years together and sometimes indefinitely. High triglyceride (TG)
may be an independent predictor of coronary heart disease. The bulk of
available evidence suggests that treatment of high TG may lower the risk of
angina/heart attack. High TG is usually treated with fibrate group of drugs
like gemfibrozil bezafibrate, ciprofibrate and fenofibrate. Statin like
atorvastatain can reduce elevated TG level up to.
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