Drugs used in treatment of Angina Pectoris.

Drugs used in the treatment of Angina Pectoris.

• Angina pectoris is clinical condition alarming cardiac ischemia characterized by sudden and acute substernal pain usually referring towards left shoulder, sometimes associated with breathlessness, anxiety, sweating and rapid irregular heartbeats.
• The drugs used in the treatment of Angina are called as "Antianginal drugs."

Mechanism of Action of Antianginal drugs:

• Basic pathophysiology of Angina, in a nutshell, is Imbalance between cardiac muscle oxygen demand and supply ----------> cardiac ischemia ------------> myocardial infarction.
• Hence the targeted drugs should act by,

1. Increasing cardiac blood supply.
2. Decreasing cardiac workload.

Classification of Antianginal Drugs:

A) Nitrates:

• They act by stimulating EDRF (Endothelial Derived Relaxing Factor).
• By causing peripheral vasodilation they reduce venous return and hence decreases cardiac workload.
• They have direct vasodilation action on coronary artery and hence relieves obstruction to blood flow and restores cardiac blood flow.
• e.g.
  

  

1. Short-Acting Nitrates:  Nitroglycerine, GTN (Glyceryl Tri Nitrate).
2. Long-Acting Nitrates: Isosorbide Mono Nitrates, Isosorbide Di Nitrate, Erythryl tetranitrate.

B) Beta Blockers:

• Beta blockers are the pharmacological agents which block actions of adrenaline mediated through adrenergic beta receptors.
• Beta-blockers hence decrease contractility, conductivity, rhythmicity and automaticity of heart.
• They are known to increase rest period of cardiac muscles.
• Hence as they reduce functioning of heart they also lower the oxygen demand and are used in prophylaxis of exertional angina (Stable angina).
• However, they are contraindicated in "variant angina (associated with spasm of a coronary artery).
• Beta blockers are also contraindicated in diabetes and heart failure.
• e.g.
  

  

1. Acebutolol.
2. Metoprolol.
3. Propranolol.
4. Oxprenolol.
5. Alprenolol.

C) Calcium Channel Blockers:

• These are peripheral vasodilators which act by blocking calcium ion channels.
• These drugs reduce venous return and hence decrease cardiac workload.
• They also possess negative chronotropic and inotropic effects.
• e.g.
  

  

1. Verapamil
2. Nifedipine.
3. Amlodipine.
4. Diltiazem.
5. Lacidipine.

D) Potassium Channel Openers.

• As the name indicates they act by opening potassium channels causing vasodilation.
• Their mechanism is identical to calcium channel blockers.
• e.g.

  

1. Minoxidil.
2. Nicorandil.
3. Diazoxide

E) Miscellaneous:

1. Dipyridamole.
2. Trimetazidine.
3. Oxyphedrine.
4. Atorvastatin.

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