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Renin Angiotensin Mechanism.

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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