Heparin does not cross the placental barrier and is not distributed into breast milk. Heparin is extensively bound to plasma proteins. injection but can be delayed 20 to 60 minutes following s.c. The onset of action is immediate after i.v. Pharmacokinetics: Heparin is not absorbed through the gastrointestinal mucosa and must be given parenterally, usually by i.v. It does not directly cause clot lysis, but prevents progression of the existing clot by inhibiting any further clotting processes, allowing naturally occurring thrombolytics to slowly effect clot lysis.Īt therapeutic doses, heparin prolongs several coagulation tests including activated coagulation time, activated partial thromboplastin time (APTT, used clinically), plasma recalcification time, prothrombin time (minimally), thrombin time and whole blood clotting time. Thrombin and factor Xa are the most sensitive to inactivation by the heparin-AT III complex. The heparin-AT III complex also inactivates activated coagulation factors IX, XI, XII and plasmin. Heparin exerts its anticoagulant activity by reversibly binding to antithrombin III (AT III), accelerating the ability of AT III to neutralize thrombin and activated coagulation factor X (Xa). Action And Clinical Pharmacology: Heparin is a heterogeneous preparation of sulfated mucopolysaccharide polymers whose molecular weights range from 3 000 to 30 000 daltons, averaging between 12 000 and 15 000 daltons.

Heparin half life