NAPLEX Practice Question # 87

NAPLEX Examination.

Practice Question # 87.


Unfractionated and low-molecular-weight heparins.

  • Unfractionated heparins (UFHs) are mucopolysaccharide polymers (60 to 100 kDa; extracted from mast cells of bovine lung tissue or porcine intestinal mucosa. Low-molecular-weight (LMWHs, 2 to 10 kDa) are produced by careful fragmentation of UFH and purifi cation by gel fi ltration to produce agents such as enoxaparin (Lovenox®), tinzaparin (Innohep®), and dalteparin (Fragmin®).
  • UFHs have high affi nity for antithrombin III (AT-III) and catalyze the inactivation of factor Xa and IIa by AT-III, ultimately reducing the amount of fi brin formed. LMWHs also bind to AT-III but preferentially inhibit factor Xa rather than IIa, but the ultimate eff ect on fi brin levels is much the same.


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