An antianginal is any drug

Medication

A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

 used in the treatment of angina pectoris, a symptom of ischaemic heart disease

Coronary heart disease

Coronary artery disease is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium with oxygen and nutrients. It is sometimes also called coronary heart disease...

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Nitrates

Nitrates cause vasodilation

Vasodilation

Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...

 of the venous capacitance vessels by stimulating the endothelium-derived relaxing factor

Endothelium-derived relaxing factor

Endothelium-derived relaxing factor is produced and released by the endothelium to promote smooth muscle relaxation. The best-characterized is nitric oxide . Some sources equate EDRF and nitric oxide....

 (EDRF). Used to relieve both exertional and vasospastic angina by allowing venous pooling, reducing the pressure in the ventricles and so reducing wall tension and oxygen requirements in the heart. Short-acting nitrates are used to abort angina attacks that have occurred, while longer-acting nitrates are used in the prophylactic management of the condition.

Agents include nitroglycerin (glyceryl trinitrate

Glyceryl trinitrate

Glyceryl trinitrate is a chemical substance used as:* a drug; see glyceryl trinitrate * an explosive; see nitroglycerin...

) or pentaerythritol tetranitrate.

Beta blockers

Beta blockers are used in the prophylaxis of exertional angina by reducing the work the heart is allowed to perform below the level that would provoke an angina attack.

They cannot be used in vasospastic angina and can precipitate heart failure.

Agents include either cardioselectives such as acebutolol

Acebutolol

Acebutolol is a beta blocker for the treatment of hypertension and arrhythmias.-Pharmacology:Acebutolol is a cardioselective beta blocker with ISA...

 or metoprolol

Metoprolol

Metoprolol is a selective β1 receptor blocker used in treatment of several diseases of the cardiovascular system, especially hypertension. The active substance metoprolol is employed either as metoprolol succinate or metoprolol tartrate...

, or non-cardioselectives such as oxprenolol

Oxprenolol

Oxprenolol is a non-selective beta blocker with some intrinsic sympathomimetic activity...

 or sotalol

Sotalol

Sotalol is a drug used in individuals with rhythm disturbances of the heart, and to treat hypertension in some individuals. It is a non-selective competitive β-adrenergic receptor blocker that also exhibits Class III antiarrhythmic properties by its inhibition of potassium channels...

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Calcium channel blockers

Calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 ion

Ion

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 (Ca⁺⁺) antagonists (Calcium channel blocker

Calcium channel blocker

A calcium channel blocker is a chemical that disrupts the movement of calcium through calcium channels.CCB drugs devised to target neurons are used as antiepileptics. However, the most widespread clinical usage of calcium channel blockers is to decrease blood pressure in patients with...

s) are used in the treatment of both exertional and vasospastic angina. In vitro, they dilate the coronary and peripheral arteries and have negative inotropic and chronotropic effects - decreasing afterload

Afterload

Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...

, improving myocardial efficiency, reducing heart rate

Heart rate

Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....

 and improving coronary blood flow.
In vivo, the vasodilation and hypotension

Hypotension

In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...

 trigger the baroreceptor

Baroreceptor

Baroreceptors are sensors located in the blood vessels of several mammals. They are a type of mechanoreceptor that detects the pressure of blood flowing through them, and can send messages to the central nervous system to increase or decrease total peripheral resistance and cardiac output...

 reflex. Therefore the net effect is the interplay of direct and reflex actions.

• Class I agents have the most potent negative inotropic effect and may cause heart failure.
• Class II agents do not depress conduction or contractility.
• Class III agent has negligible inotropic effect and causes almost no reflex tachycardia
  Tachycardia
  Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
  
  .

Examples include Class I agents (e.g., verapamil

Verapamil

Verapamil is an L-type calcium channel blocker of the phenylalkylamine class. It has been used in the treatment of hypertension, angina pectoris, cardiac arrhythmia, and most recently, cluster headaches. It is also an effective preventive medication for migraine...

), Class II agents (e.g., amlodipine

Amlodipine

Amlodipine is a long-acting calcium channel blocker used as an anti-hypertensive and in the treatment of angina...

, nifedipine

Nifedipine

Nifedipine is a dihydropyridine calcium channel blocker...

), or the Class III agent diltiazem

Diltiazem

Diltiazem is a non-dihydropyridine member of the class of drugs known as calcium channel blockers, used in the treatment of hypertension, angina pectoris, and some types of arrhythmia....

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