indication

Dalteparin is used as a prophylaxis for deep-vein thrombosis and pulmonary embolisms in patients undergoing general surgery (e.g., abdominal, gynecologic, urologic), and in patients with acute medical conditions (e.g. cancer, bed rest, heart failure, severe lung disease). It is also used in patients who have severely restricted mobility, which poses a risk for thromboembolic complications. Dalteparin is also used concomitantly with aspirin and/or other therapy (e.g., nitrates, β-adrenergic blockers, clopidogrel, platelet glycoprotein [GP] IIb/IIIa-receptor inhibitors) to reduce the risk of acute cardiac ischemic events. The patients who undergo this treatment combination have unstable angina or non-ST-segment elevation/non-Q-wave myocardial infarction (i.e., non-ST-segment elevation acute coronary syndromes). It is also used in the prevention of clotting during hemodialysis and hemofiltration in connection with acute renal failure or chronic renal insufficiency.

pharmacology

Dalteparin has an antithrombin binding site that is essential for high affinity binding to the plasma protein antithrombin (ATIII). Anti-Xa activity of plasma is used as both as an estimate of clotting activity, and as a basis to determine dosage. Its use should be avoided in patients with a creatinine clearance less than 20mL/min. In these patients, unfractionated heparin should only be used. As for monitoring, active partial thromboplastin time (aPTT) will only increase at high doses of low molecular weight heparins (LMWH). Therefore, monitoring aPTT is not recommended. However, anti-Xa activity can be measured to monitor the efficacy of the LMWH.

mechanism of action

Dalteparin potentiates the activity of ATIII, inhibiting the formation of both factor Xa and thrombin. The main difference between dalteparin and unfractionated heparin (UH) is that dalteparin preferentially inactivates factor Xa. As a result, only a slight increase in clotting time [(i.e. activated partial thomboplastin time (APTT)] is observed relative to UH. For this same reason, APTT is not used to monitor the effects of dalteparin except as an indicator for overdosage.

toxicity

Overdosage: hemorrhagic complications. Adverse Drug Reaction: (common) osteopenia with extended use; mild, reversible non-immunological thrombocytopenia; transient elevation of liver transaminases; alopecia. (uncommon): severe immunologically-mediated heparin-induced thrombocytopenia; anaphylactic reactions; skin rash, skin necrosis; retroperitoneal hemorrhage; angioedema

biotransformation

Liver and the reticulo-endothelial system are the sites of biotransformation. They are partially metabolized by desulphatation and depolymerization.

absorption

Almost completely absorbed after subcutaneous (sc) doses, with a bioavialability of about 87%.

half life

Terminal Half life: Intravenous - 2 hours. Subcutaneous - 3-5hours

route of elimination

After 4 hours, about 20% is seen in urine. Most of the remainder is found in the liver, gastrointestinal tract and kidney. The kidneys are the major site of dalteparin excretion (approximately 70% based on animal studies).