Saturday, April 5, 2008

101 - acute coronary syndrome

A spectrum of myocardial ischemic disorders characterized by atherothrombotic plaque disruption which results in unstable angina, Non–ST-elevation myocardial infarction (NSTEMI), ST-elevation myocardial infarction (STEMI)

Acute myocardial ischemia is chest pain due to insufficient blood supply to the heart muscle that results from coronary artery disease (also called coronary heart disease).

Patients who have symptoms of acute myocardial ischemia and who are made to undergo electrocardiogram (ECG or EKG) may or may not have an ST elevation. (An ECG provides a graph of the heartbeat. Portions of the graph are labeled P, Q, R, S and T. An ST elevation describes a rise in a particular portion of this graph.) Most patients who have ST-segment elevation will ultimately develop a Q-wave acute myocardial infarction (heart attack). (The Q-wave describes another part of an ECG graph.) Patients who have ischemic discomfort without an ST-segment elevation are having either unstable angina, or a non-ST-segment elevation myocardial infarction that usually leads to a non-Q-wave myocardial infarction.

Acute coronary syndrome thus covers the spectrum of clinical conditions ranging from unstable angina to non-Q-wave myocardial infarction and Q-wave myocardial infarction. These life-threatening disorders are a major cause of emergency medical care and hospitalization in the United States. Coronary heart disease is the leading cause of death in the United States. Unstable angina and non-ST-segment elevation myocardial infarction are very common manifestations of this disease.

The drugs used for the treatment of ACS

Anticoagulants: delay/prevent clot formation and extension (Heparin, LMWH)

  • Unfractionated Heparin (UFH) : Widely used antithrombotic agent but has the disadvantages of Heparin Induced Thrombocytopenia (HIT)
  • Low-Molecular-Weight Heparin (LMWH) : Fraction of standard (UFH) heparin, effective subcutaneous administration. Egs. enoxaparin, dalteparin, reviparin, nadroparin, fraxiparin.

LUPENOX (Enoxaparin 20, 40, 60mg PFS). Lupenox is in-licensed from Italfarmaco,Italy.

Antiplatelet drugs: interfere with platelet activity (ASA, CLOPIDOGREL, GP IIb/IIIa Inhibitors)

  • Aspirin (ASA) : Prevents platelet aggregation by blocking TxA2
  • Clopidogrel / Ticlopidine : Inhibit ADP-dependent activation of GP IIb/IIIa complex. Useful in patients hypersensitive to ASA or predisposed to GI bleeding. Also used in combination with ASA in the management of ACS.
  • Abciximab, Eptifibatide, Tirofiban : Inhibits the GP IIb/IIIa inhibitors and thus prevents platelets from binding to each other
  • Cilostazol - An add-on to other antiplatelet agents, helps in the management of Intermittent Claudication and also in prevention of Restenosis

CLOPITAB (Clopidogrel 75mg)

CLOPITAB-A (Clopidogrel 75mg + Aspirin 75/150mg)

TIROFUSE (Tirofiban 5mg/100ml I.V injection)

CILODOC (Cilostazol 50,100mg)

Thrombolytic agents: (Plasminogen Activators) dissolve existing thrombi (tPA, Streptokinase). A number of ongoing large randomized trials are attempting to determine whether the combination of fibrinolytic therapy with low-molecular-weight heparin or a glycoprotein IIb/IIIa antagonist enhances coronary reperfusion and reduces mortality and late reocclusion.

l Streptokinase - The most widely used thrombolytic agent and can now be made using recombinant DNA technology

l Alteplase, Reteplase and Tenecteplase – Offers more powerful results in dissolving the thrombus. In combination with Enoxaparin reduces early ischemic events

Isosorbide-5-mononitrate: An anti-anginal agent which helps balance the oxygen demand and supply in patients suffering from Angina.

ISONORM (Isosorbide-5-mononitrate 10, 20, 30mg SR)

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