Drugs

Antianginal Drugs : Classification, Uses, & Side Effects

Antianginal Drugs : Definition, Pharmacology, Mechanism of action, Classification, Examples, List, Uses, & Side Effects

Definition

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

Classification

1. Nitrates

  • All organic nitrates share the same action; differ only in time course.
  • The only major action is direct nonspecific smooth muscle relaxation.
  • E.g.
    Short acting Long acting
    Nitroglycerine / Glyceryl trinitrate (GTN) Isosorbide dinitrate
    Isosorbide mononitrate
    Erythrityl tetranitrate
    Pentaerythritol tetranitrate

2. β-blockers

  • These drugs do not dilate coronaries or other blood vessels.
  • They act by reducing cardiac work and O2 consumption (decreased heart rate, inotropic state and mean BP). This is marginal at rest.
  • More importantly, β-blockers limit increase in these modalities that occurs during exercise or anxiety (due to anti-adrenergic action on heart).
  • All β-blockers are nearly equally effective in decreasing frequency and severity of attacks and in increasing exercise tolerance in classical angina, but cardioselective agents (atenolol, metoprolol) are preferred over nonselective β1 +β-2 blockers (e.g. propranolol), which may worsen variant angina due to unopposed a receptor mediated coronary constriction that may accentuate the coronary spasm.

3. Ca++ channel blockers (CCBs)

  • The problem of rebound worsening of angina on withdrawal after chronic use is less with CCBs than with β-blocker.

E.g.

  • Verapamil
  • Nifedipine
  • Diltiazem

4. K+ channel opener

  • There are multiple types of K+ channels, e.g. voltage dependent, Ca2+ activated, receptor operated, ATP sensitive, Na+ activated and cell volume sensitive which serve diverse functions and exhibit different sensitivities to drugs.
  • As such, K+ channel openers exhibit considerable diversity in action.
  • The most prominent action of K+ channel openers is smooth muscle relaxation-vascular as well as visceral: their potential clinical applications are primarily based on this property.
  • E.g.
  • NicorandilPinacidil

    Cromakalim

5. Na+ channel blockers

  • E.g. Ranolazine

6. Other

  • Dipyridamole
  • Trimetazidine
  • Oxyfedrine

Uses

  • Used to abort or terminate attack- GTN, Isosorbide dinitrate (sublingually)
  • Used for chronic prophylaxis – All other drugs
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