Antianginal Drugs

Types of Angina

Stable Angina1) The experience is quite variable, often

described as chest pain & associated with adjectives indicating a compressive tightness.

2) Angina indicates that myocardial oxygen demand is exceeding supply. “Stable” indicates the reproducible nature of the angina; the same activity at the same intensity faithfully produces symptoms.

3) Typically this type of angina is relieved by rest or acute use of nitroglycerin.

Unstable Angina

1) when anginal symptoms occur with less cardiac demand; previously tolerated activities elicit symptoms, of great concern is angina at rest.

2) These episodes are less or un-responsive to nitroglycerine or rest.

Prinzmetal (Variant) Angina1) uncommon pattern of myocardial ischemia

usually occurring at rest and often in young individuals (particularly women)

2) The anginal attacks have a circadian rhythm and generally occur in the early morning hours.

3) attacks can be triggered by alcohol, drinking iced drinks, rapid eye movement sleep, ergonovine, atrial pacing, cocaine, nicotine, acetylcholine, and hyperventilation.

4) It is induced by coronary artery vasospasm it generally responds promptly to vasodilators. It is associated with other vasospastic disorders such as migraine headaches and Raynaud’s phenomena. Endothelial dysfunction has been considered as primarily responsible for this.

5) The risk of both ventricular & bradyarrthymias is markedly increased during spastic events, sudden cardiac death is not uncommon.

Classes effective in treating angina:

1. Vasodilator or organic nitrates or nitro-vasodilator

Nitroglycerine

2. β-blockers – Propranolol

3. Ca+2 channel blockers- Verapamil, Diltiazem,

Nifedipine

4. Antithrombotic agent- Aspirin, Clopidrogel

Nitrovasodilatorstored inendothelial cells

MetabolicTransformationin Vascular SM

Nitric oxide(No)

Guanylate cyclase

Activate

GTP C GMP

ProteinKinase

MLCKMLCK-PO4(inactive)

Muscle Relax

Nitroglycerine is effective because:-

1) Redistribution of coronary blood flow to the ischemic

region

2) Decreased myocardial oxygen demand

3) Redistribution of blood causes pooling of blood in

Peripheral veins

4) decreased in ventricular volume, stroke volm.

Adverse effects:1. The most common side effect of nitrates is headache due

to veno-dilation, 2. Postural hypotension3. Tachycardia4. Methemaglobinemia can occur with chronic use of long

term agents, 5. Withdrawal symptoms may occur (an indication of

tolerance) when nitrate agents are tapered or discontinued, this may precipitate anginal attacks.

1) Glyceryl Trinitrate (Nitroglycerin):- Trinitrin,Nitroglyn

PP:- 1) Clear colourless oily volatile liquid 2) Odourless but sweet in taste 3) Soluble in water , glycerol and freely

soluble in alcoholUse’s:- 1) For treatment of Angina Pectoris

2) For unstable angina3) To treat CHF4) Post operative hypertension

Stability :- 1) Volatile in Nature & affected by light.

Storage:- In a glass container with tightly fitting metal screw cap

PPn:- 1) N.tablet-USP 2) N. Ointment-BPC

Reasons for Using Nitrates and Beta Blockers in Combination in Angina

• Beta Blockers prevent reflex tachycardia and contractility produced by nitrate-induced hypotension.

• Nitrates prevent any coronary vasospasm produced by Beta Blockers.

• Nitrates prevent increases in left ventricular filling pressure or preload resulting from the negative inotropic effects produced by Beta Blockers.

• Nitrates and Beta Blockers both reduce myocardial oxygen consumption by different mechanisms.

• Nitrates and Beta Blockers both increase subendocardial blood flow by different mechanisms