Anti-Anginal Drugs – Uses, Effects, side Effects

Introduction

Antianginal drugs are those that prevent, abort or terminate attacks of angina pectoris.

Angina pectoris Is a pain syndrome due to induction of an adverse oxygen supply/demand situation in a portion of the myocardium.

How do antianginal drugs work?

These drugs act by increasing coronary blood flow and oxygen supply, or by preventing vasospasm and clot formation, and associated decreases in blood flow. Drugs that reduce myocardial oxygen demand are also given to patients with these two forms of angina to reduce oxygen demand and thereby help to alleviate the pain.

Types of angina

The most common types are chronic stable angina and unstable angina.

Chronic stable angina Chest pain occurs when your heart is working hard enough to need more oxygen, such as during exercise. The pain can go away when you rest. Vise versa in unstable angina

Common side effect of an anti anginal agent?

May cause redistribution of coronary blood flow from normal to ischemic tissue. Nitrates (and calcium channel blockers) may also increase myocardial oxygen delivery in variant angina by reversing coronary arterial spasm.

Several medications can improve angina symptoms, including:

• Aspirin. Aspirin and other antiplatelet medications reduce the ability of your blood to clot, making it easier for blood to flow through narrowed heart arteries.
• Nitrates.
• Beta blockers
• Calcium channel blocker
• Ranolazine (Ranexa).

First line treatment

Beta blockers are first-line therapy to reduce angina and improve exercise tolerance by limiting the heart rate response to exercise.

Angina is caused by reduced blood flow to your heart muscle. Your blood carries oxygen, which your heart muscle needs to survive. When your heart muscle isn’t getting enough oxygen, it causes a condition called ischemia. The most common cause of reduced blood flow to your heart muscle is coronary artery disease (CAD).

The fastest way to cure angina

If you need immediate relief from your angina:

1. Stop, relax, and rest. Lie down if you can.
2. Take nitroglycerin.
3. If the pain or discomfort doesn’t stop a few minutes after taking nitroglycerin or if your symptoms become more severe, call 911 or let someone know that you need immediate medical assistance.

CLASSIFICATION OF DRUGS

1. Nitrates
   1. Short acting: Glyceryl trinitrate (GTN) Nitroglycerine
   2. Long acting Isosorbide dinitrate (short acting by sublingual route), Isosorbide mononitrate, Erythrityl tetranitrate, Pentaerythritol tetranitrate
2. Beta Blockers :-Propranolol, Metoprolol, Atenolol
3. Calcium channel blockers
   1. Phenyl alkylamine: Verapamil
   2. Benzothiazepine: Diltiazem
   3. Dihydropyridines: Nifedipine, Felodipine, Amlodipine, Nitrendipine, Nimodipine, Lacidipine, Lercanidipine
4. Potassium channel opener Nicorandil, Benidipine
5. Others :Ranolazine, Ivabradine, Oxyfedrine, dipyridamole, Trimetazidine

Drugs in detail

NITRATES

NITRATES helps to relieve the pain of a current attack, or treat the symptoms of heart failure, limit the number of attacks.

Nitroglycerin is a type of nitrate.

• Glyceryl trinitrate (GTN) is a spray used to relieve angina (chest pain). When sprayed under the tongue, it relaxes and widens blood vessels in the heart and in the rest of the body.
• Isosorbide dinitrate is used to prevent chest pain (angina) in patients with a certain heart condition (coronary artery disease). This medication belongs to a class of drugs known as nitrates. It works by relaxing and widening blood vessels so blood can flow more easily to the heart.
• Isosorbide mononitrate is a prescription drug indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of oral isosorbide mononitrate is not sufficiently rapid for this product to be useful in aborting an acute anginal episode.
• Erythritol tetranitrate It is a vasodilator with properties similar to nitroglycerin. It is usually used diluted with lactose or other suitable inert excipients, in order to minimise the risk of explosion; undiluted erythrityl tetranitrate can be exploded by percussion or excessive heat. It has a role as a vasodilator agent and an explosive.
• Pentaerythritol tetranitrate is the nitrate ester of pentaerythritol that possesses explosive properties. When recognized by the FDA to be a mixed with a plasticizer, this chemical forms a plastic explosive. It is coronary vasodilator in the treatment of heart conditions such as angina.

BETA BLOCKERS

These are used to prevent, treat or improve symptoms in people who have:

• Irregular heart rhythm (arrhythmia)
• Heart failure.
• Chest pain (angina)
• Heart attacks.
• Migraine.
• Certain types of tremors.
• propranolol, metoprolol, atenolol are some examples.

CALCIUM CHANNEL BLOCKERS

Examples- varapamil etc

These are drugs used to lower blood pressure. They work by slowing the movement of calcium into the cells of the heart and blood vessel walls, which makes it easier for the heart to pump and widens blood vessels. As a result, the heart doesn’t have to work as hard, and blood pressure lowers.

POTASSIUM-CHANNEL OPENERS

These are the drugs that activate (open) ATP-sensitive K+ channels in vascular smooth muscle. Opening these channels hyperpolarizes the smooth muscle, which closes voltage-gated calcium channels and decreases intracellular calcium.

• Nicorandil is a type of medicine called a potassium-channel activator. It works by relaxing and widening your blood vessels, which increases the supply of blood and oxygen to your heart. This helps reduce the chest pain angina causes.

OTHER DRUGS

• Dipyridamole is a nucleoside transport inhibitor and a PDE3 inhibitor medication that inhibits blood clot formation when given chronically and causes blood vessel dilation when given at high doses over a short time.
• Trimetazidine is a drug for angina PECTORIS sold under many brand names. Trimetazidine is described as the first cytoprotective anti-ischemic agent developed.
• Ranolazine, sold under the brand name RANEXA among others, is a medication used to treat heart related chest pain. Typically it is used together with other medications when those are insufficient. Benefits appear smaller in women than men. It is taken by mouth.
• Ivabradine, marketed under trade names including CORALAN, CORLANOR, PROCORALAN, CORAXAN, and many more, is a medication used for the symptomatic management of stable heart-related chest pain and heart failure not fully managed by beta blockers.
• Oxyfedrine is a vasodilator and a B adrenoceptor agonist. It was found to depress the tonicity of coronary vessels, improve myocardial metabolism and also exert a positive chronotropic and inotropic effects, thereby not precipitating angina pectoris.

Side Effects

• Dizziness.
• Flushing
• Headache.
• Transient hypotension.
• Peripheral edema.