Heparin and Low-Molecular-Weight Heparin Mechanisms of Action, Pharmacokinetics, Dosing, Monitoring, Efficacy, and Safety

Heparinand its derivative, low-molecular-weight heparin (LMWH), are theanticoagulants of choice when a rapid anticoagulant effect is required, because their onset of action is immediate when administered by IVinjection. Both types of heparins are administered in lower doses forprimary prophylaxis than for treatment of venous thrombosis or acutemyocardial ischemia. Heparin has pharmacokineticlimitations1 not shared by LMWHs. Based on thesepharmacokinetic limitations, heparin therapy is usually restricted tothe hospital setting, where its effect can be monitored and its dosageadjusted frequently.