Heparin: Which Molecule? What Clinical Applications?

Heparin is a highly sulphated glycosaminoglycan discovered about 90 years ago, and since then widely used in Medicine as an anticoagulant drug, administered for parenteral, intravenous and subcutaneous. Antithrombin (AT) is a small protein molecule that inactivates several enzymes of the coagulation system. Heparin catalyzes antithrombin function, especially on IIa and Xa factors. Heparins are divided into two major groups: unfractionated heparin (UH), discovery over 90 years ago and in medical use from the 30s, that is a glycosaminoglycan of great molecular weight (from 3000 to 30000 Dalton); Low molecular weight heparin (LMWH) that are fragments of native heparin, obtained by its chemical or enzymatic depolymerization (molecular weight 4000-5000 Dalton average). Heparin consist of a variably sulphate repeating disaccharide unit. Heparin implements its anticoagulant action by binding to AT through an active molecular fragment: the pentasaccharide sequence. UH is commonly used during some invasive medical procedures (ex. hemodialysis). It is also used in primary prevention of venous thromboembolism (VTE) in high risk subjects but in this case LMWH and fondaparinux are more effective, easier in clinical management and equivalent in security. Another field of application of UH is the treatment of VTE though American College of Chest Physicians (ACCP) evidencebased clinical practice guidelines 9th ed. 2012 suggest to use as first option LMWH and Fondaparinux versus UH. Finally, the use of UE is indicated in the early treatment of Non ST-elevation myocardial infarction (N-STEMI) in association with antiplatelet agents. In therapeutic management of ST-elevation myocardial infarction (STEMI) if patient is about to undergoes to primary percutaneous coronary intervention (PCI) , UH must be used in patients not receiving bivalirudin or enoxaparin. In fibrinolytic therapy anticoagulation is recommended in STEMI patients treated with lytics until revascularization (if performed) or for the duration of hospital stay up to 8 days, the anticoagulant can be UH as alternative to Enoxaparin, that's the first line anticoagulant. For several years LMWH and fondaparinux have become the treatment of choice for prophylaxis and treatment of VTE. In fact they have a better pharmacokinetics than UH, which allows the routine use in a fixed dose without the need for laboratory controls assays. The dosage is determined by the weight of the patient, kidney function and the specific therapeutic indication. © 2014 by Nova Science Publishers, Inc. All rights reserved.