Which medications in the drug class Thrombolytics are used in the treatment of Myocardial Infarction?

Updated: May 07, 2019
  • Author: A Maziar Zafari, MD, PhD, FACC, FAHA; Chief Editor: Eric H Yang, MD  more...
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Answer

Thrombolytics

The main objective of thrombolysis is to restore circulation through a previously occluded vessel by the rapid and complete removal of a pathologic intraluminal thrombus or embolus that has not been dissolved by the endogenous fibrinolytic system.

The first generation of fibrinolytic drugs (eg, streptokinase, urokinase, acetylated plasminogen streptokinase activator complexes [APSACs], reteplase, and novel plasminogen activator [nPA]) indiscriminately induced activation of circulating plasminogen and clot-associated plasminogen. First-generation drugs invariably elicited a systemic lytic state characterized by depletion of circulating fibrinogen, plasminogen, and hemostatic proteins and by marked elevation of concentrations of fibrinogen degradation products in plasma.

Second-generation drugs (eg, alteplase [t-PA], single-chain urokinase plasminogen activator), such as tenecteplase, preferentially activate plasminogen in the fibrin domain, rather than in the circulation, as with free plasminogen. Therefore, they have clot selectivity. Tenecteplase should be initiated as soon as possible in patients with STEMI; tenecteplase is administered as a single bolus, exhibiting a biphasic disposition from the plasma.

In optimal regimens, these agents induce clot lysis without inducing a systemic lytic state, they are less prone than nonselective agents to predispose the patient to hemorrhage necessitating transfusion, and they are effective in inducing recanalization in 80-90% of infarct-related arteries within 90 minutes. Therefore, t-PA recanalizes 75-80% of infarct-related arteries.

Alteplase, t-PA (Activase)

Alteplase (t-PA) is a fibrin-specific agent with a brief half-life of 5 minutes. Adjunctive therapy with IV heparin is necessary to maintain the patency of arteries recanalized by t-PA, especially during the first 24-48 hours.

Tenecteplase (TNKase)

Tenecteplase is a modified version of alteplase (t-PA) made by substituting 3 amino acids of alteplase. It can be given as a single bolus over a 5-second infusion, instead of 90 minutes with alteplase. Tenecteplase appears to cause less nonintracranial bleeding, but the risk of intracranial bleeding and stroke is similar to that of alteplase. Base the dose using patient weight. Initiate treatment as soon as possible after the onset of acute STEMI symptoms. Because tenecteplase contains no antibacterial preservatives, reconstitute immediately before use.


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