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Low molecular weight heparins in the treatment of unstable angina
1McMaster University, Hamilton, Canada.
Insights
Low molecular weight heparins offer improved efficacy and safety over unfractionated heparin for acute coronary syndromes. Clinical trials show these agents are effective alternatives, but direct comparisons are needed to determine superiority.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Unstable angina and acute coronary syndromes stem from atherosclerotic plaque disruption and thrombus formation.
- Antithrombotic therapy, particularly aspirin and unfractionated heparin, is crucial for preventing myocardial infarction.
Purpose of the Study:
- To evaluate the efficacy and safety of low molecular weight heparins (LMWHs) compared to unfractionated heparin in managing unstable angina and non-Q-wave myocardial infarction.
- To highlight the practical advantages of LMWHs in clinical settings.
Main Methods:
- Review of clinical trials involving three LMWHs: nadroparin, dalteparin, and enoxaparin.
- Comparison of LMWHs with unfractionated heparin in terms of efficacy, safety, and pharmacokinetic/pharmacodynamic properties.
Main Results:
- LMWHs demonstrated comparable safety and efficacy to unfractionated heparin.
- LMWHs offer significant practical benefits, including subcutaneous administration and fixed dosing without monitoring.
- Published trials suggest LMWHs are effective alternatives for acute coronary syndrome management.
Conclusions:
- Low molecular weight heparins are recommended as alternatives to unfractionated heparin in the acute management of acute coronary syndromes.
- Apparent differences in outcomes between LMWH agents necessitate direct comparative studies to establish superiority.
Abstract:
Unstable angina is in most cases caused by partial or complete coronary artery occlusion due to the disruption of an atherosclerotic plaque and resultant thrombus formation. Platelet aggregation and thrombin formation are key events in the development of acute coronary syndromes. An immediate antithrombotic approach is essential to prevent fatal and non-fatal myocardial infarction, and the combination of aspirin and unfractionated heparin has been the treatment of choice in the past years. Low molecular weight heparins have improved pharmacokinetic and pharmacodynamic properties over unfractionated heparin that have resulted in greater efficacy and safety in the field of venous thromboembolism. Low molecular weight heparins can be administered by subcutaneous injections at fixed, weight adjusted doses without need for monitoring. Three low molecular weight heparins have been tested in adequately sized clinical trials in patients with unstable angina and non-Q-wave myocardial infarction: nadroparin, dalteparin and enoxaparin. The results of the published trials have confirmed that the newer compounds are at least as safe and effective as unfractionated heparin offering considerable practical and clinical advantages. Low molecular weight heparins are currently recommended as alternative to unfractionated heparin in the acute management of acute coronary syndromes. Nevertheless, the different properties of these compounds and possibly the different designs of the clinical trials have resulted in apparent differences in clinical outcomes with the different agents. Direct comparisons are now required to determine the superiority of one compound over another.