indication

Tinzaparin is used for the prevention of postoperative venous thromboembolism in patients undergoing orthopedic surgery and in patients undergoing general surgery who are at high risk of developing postoperative venous thromboembolism. It is also used for the treatment of deep vein thrombosis and/or pulmonary embolism. It is indicated for use in preventing clot formation in indwelling intravenous lines for hemodialysis.

pharmacology

Tinzaparin, like other LMWHs, have a higher anti-Xa activity than anti-IIa activity. The anti-Xa activity of tinzaparin is 2.0 +/- 0.5 times greater than its to anti-IIa activity. Heparin exhibits approximately equal inhibitory activity against Xa and IIa. Tinzaparin is an anticoagulant that blocks the formation of thrombi. Like all LMWHs, tinzaparin only causes activated partial thromboplastin time (aPTT) prolongation at higher doses and routine monitoring is not recommended. However, anti-factor Xa levels may be monitored in some conditions such as pregnancy and renal dysfunction. Its use should be avoided in patients with a creatinine clearance less than 20 mL/min. In these patients, unfractionated heparin should be used. Tinzaparin can be used in patients who have a creatinine clearance between 20-30 mL/min, giving it the highest safety threshold for use in renal failure patients compared to all the LMWHs.

mechanism of action

Tinzaparin binds to the plasma protein antithrombin III, forming a complex with then accelerates the inhibition of factor Xa. Its affinity for factor Xa is 2-4 times greater than that of unbound ATIII. The inactivation of factor Xa in turn will exponentially generation of thrombin (factor IIa) molecules, which is needed to activate fibrinogen to fibrin. The coagulation cascade is inhibited because fibrin cannot be formed in the presence of tinzaparin. Like all LMWH, it cannot be given intramuscularly due to increased risk of hematoma.

toxicity

Osteoporosis with increasing duration of use, bleeding, alopecia, heparin induced thrombocytopenia (HIT). All of these adverse drug reactions occur less with LMWH compared to unfractionated heparin. Tinzaparin showed no toxic effects at doses up to 5 mg/kg in mice, rats, or dogs in standard acute, subacute, and chronic toxicity studies.

biotransformation

Sulfation and polymerization occurs in the liver.

absorption

Subcutaneous injection - about 90% when measured as anti-Xa activity versus 67% for anti-IIa activity.

half life

Anti-Xa activity is 82 minutes. Anti-IIa activity is 71 minutes.

route of elimination

Linear elimination through kidneys