Where is heparin metabolized

Many of the difficulties inherent in assessing the kinetic properties of heparin, as well as its clinical efficacy, may be attributed to: 1 its molecular heterogeneity; 2 its wide spectrum of binding sites and their respective kinetic properties and dissociation constants; 3 differences among methods for measuring heparin effect and concentration; 4 the dose dependence of the drug's half-life; 5 variation in patient response to heparin; 6 the specific cation associated with it; and 7 the presence of hypercoagulation syndromes associated with deficits of antithrombin.

Neither renal nor hepatic disease, nor the biological tissues from which heparins are extracted commercially, seem to influence the drug's kinetic properties as much as variations in clearance and response to heparin among individual patients. Many comparisons among available studies are difficult because of the wide variation in the assay methods employed in them.

This model accounts for the major pharmacokinetic properties of UH. After bolus intravenous injection of low doses, UH disappears from the blood exponentially with a dose-dependent half-life; at higher doses, UH disappears with a concave-convex pattern.

Under continuous intravenous infusion there is a non-linear relationship between the dose of UH injected and the steady-state plasma concentration. Louis, Missouri. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. Heparin Metabolism: Isolation and Characterization of Uroheparin. Nature , — Download citation. Issue Date : 15 October Anyone you share the following link with will be able to read this content:.

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By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. The formation of antithrombin - heparin complex greatly increases the rate of inhibition of two principle procoagulant proteases, factor Xa and thrombin.

Accelerated inactivation of both the active forms of proteases prevents the subsequent conversion of fibrinogen to fibrin that is crucial for clot formation. As the name implies low-molecular-weight heparins are preparations that have lower average molecular weight than heparin. The average molecular weight of these LMW heparins typically ranges from 2, to 8, Da.

They are made by enzymatic or chemical controlled hydrolysis of unfractionated heparin. These molecules have very similar chemical structure as unfractionated heparin except for some changes that may have been introduced due to the enzymatic or chemical treatment. The mechanism of action of these drugs is the same as full-length heparin. The overall advantage in the use of these LMW heparins appears to be in the decreased need for monitoring patients in comparison to heparin.

Differences of opinion exist and further testing will determine whether these will continue to be used. The first LMW heparin, enoxaparin, has been approved for preventing blood clots following hip replacement surgery.