Dosing and uses of Antithrombin Recombinant, Atryn (antithrombin alfa)
Adult dosage forms and strengths
injectable solution
- 1750 International Unit/vial
Therapeutic treatment goal: to increase & maintain antithrombin activity between 80-120% (0.8-1.2 International Unit/mL) during treatment
Initial treatment: Loading dose targeting 100% AT activity level based on weight & pretreatment AT activity leveL
Surgical Patients
Load = [(100 - baseline AT activity level in %)/2.3] x kg Body Weight IV infuse over 15 minutes
Maintenance (International Unit/hr) = [(100 - baseline AT activity level in %)/10.2] x kg BW IV continuous infusion
Pregnant
Load = [(100 - baseline AT activity level in %)/1.3] x kg Body Weight IV infuse over 15 minutes
Maintenance (International Unit/hr) = [(100 - baseline AT activity level in %)/5.4] x kg BW IV continuous infusion
Dose Adjustments
Draw AT activity levels 2 hours after start of loading dose, AFTER start of maintenance dose infusion
- IF AT activity level 80%-120% (0.8-1.2 International Unit/mL): NO dose adjustment
- If AT activity level <80%: Increase maintenance infusion rate by 50%
- If AT activity level >120%: Decrease infusion rate by 30%
Other Indications & Uses
Prophylaxis of venous thromboembolism in surgery of patients with congenital antithrombin deficiency
Given in association with heparin or LMW heparin
Pediatric dosage forms and strengths
No experience
Antithrombin Recombinant, Atryn (antithrombin alfa) adverse (side) effects
1-10%
Application site pruritus (2%)
Chest pain; non cardiac (2%)
Dizziness
Dyspnea
Headache
Hemorrhage (5%)
Hepatic enzyme changes ( 2%)
Infusion site reaction (5%)
Nausea
Venipuncture site hemorrhage
Post procedural hemorrhage
Wound secretion
Warnings
Contraindications
Hypersensitivity to goat protein or goat milk components
Cautions
May incr risk of bleeding
Monitor pts for possible immunological rxns, incl antibody status
Provide appropriate clinical testing when antithrombin is used with heparin or other anticoagulants
Perform anticoagulation studies (APTT, anti-Factor Xa) at close intervals when starting antithrombin Tx
Measure antithrombin levels daily, in order to adjust individual dose
Risk of diminishing antithrombin levels with prolonged Tx w/ non-fractionated heparin
Pregnancy and lactation
Pregnancy category: C
Lactation: enters breast milk; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Antithrombin Recombinant, Atryn (antithrombin alfa)
Half-Life, distribution: 1.74±1.28 hr; elimination: 10.16±1.28 hr
Mechanism of action
Serine protease inhibitor; important natural inhibitor of blood coagulation; inhibits thrombin & Factor VIIa/tissue factor complex
Administration
IV Preparation
Bring vial to room temp prior to reconstitution; keep no longer than 3 hr
Reconstitute preparation with 10 mL SWI injected along side walL
Gently swirl, don't shake
Inspect visually for particulate matter & discoloration prior to administration
- do NOT use if deposits or cloudiness present
Draw reconstituted product into sterile disposable syringe
IV Administration
Administer by IV infusion using sterile syringe or infusion bag w/ 0.22 micron pore inline filter
May add NS to dilute for admininistration purposes
Use infusion soln within 8 hr of preparation
Compatible w/ PVC infusion lines with inline filters
Initial infusion over 15 min, then continuous infusion
Storage
Store in refrigerator (2-8°C)
