"The U.S. Food and Drug Administration yesterday approved Obizur [Antihemophilic Factor (Recombinant), Porcine Sequence] for the treatment of bleeding episodes in adults with acquired hemophilia A (acquired Factor VIII [FVII] deficiency).
ATryn® is a recombinant antithrombin indicated for the prevention of peri-operative and peri-partum thromboembolic events in hereditary antithrombin deficient patients1.
It is not indicated for treatment of thromboembolic events in hereditary antithrombin deficient patients.
DOSAGE AND ADMINISTRATION
For Intravenous Use Only after Reconstitution
Preparation for Administration
- Bring vials to room temperature no more than 3 hours prior to reconstitution.
- Reconstitute with 10 mL Sterile Water for Injection [(WFI) not supplied with ATryn (recombinant lyophilized powder) ] immediately prior to use. Do not shake.
- Do not use solution containing visible particulates or if it is discolored or cloudy.
- Draw solution from one or more vials into a sterile disposable syringe for intravenous administration or add solution to an infusion bag containing 0.9% sterile sodium chloride for injection (e.g., dilute solution to obtain a concentration of 100 IU/mL).
- Administer using an infusion set with a 0.22 micron pore-size, in-line filter.
- Administer contents of infusion syringes or diluted solution within 8 to 12 hours of preparation when stored at room temperature (68-77°F (20-25°C)).
- Discard unused product in accordance with local requirements.
Recommended Dose and Schedule
- The dosage of ATryn (recombinant lyophilized powder) is to be individualized based on the patient's pretreatment functional AT activity level (expressed in percent of normal) and body weight (expressed in kilograms) and using therapeutic drug monitoring (Table 1).
- The goal of treatment is to restore and maintain functional antithrombin (AT) activity levels between 80% - 120% of normal (0.8 - 1.2 IU/mL).
- Treatment should be initiated prior to delivery or approximately 24 hours prior to surgery to ensure that the plasma antithrombin level is in the target range at that time.
- Different dosing formulae are used for the treatment of surgical and pregnant patients. Pregnant women who need a surgical procedure other than Cesarean section should be treated according to the dosing formulae for pregnant patients.
- Administer loading dose as a 15-minute intravenous infusion, immediately followed by a continuous infusion of the maintenance dose.
- AT activity monitoring and dose adjustments should be made according to Table 2.
- Continue treatment until adequate follow-on anticoagulation is established.
Table 1: Dosing Formula for Surgical Patients and Pregnant
|Loading Dose (IU)||Maintenance Dose (IU/hour)|
|Surgical Patients||(100 - baseline AT activity level)/2.3||x Body Weight (kg)||(100 - baseline AT activity level)/10.2||x Body Weight (kg)|
|Pregnant Women||(100 - baseline AT activity level)/1.3||x Body Weight (kg)||(100 - baseline AT activity level)/5.4||x Body Weight (kg)|
AT Activity Monitoring and Dose Adjustment
AT activity monitoring is required for proper treatment. Check AT activity once or twice per day with dose adjustments made according to Table 2.
Table 2: AT Activity Monitoring and Dose Adjustment
|Initial Monitor Time||AT Level||Dose Adjustment||Recheck AT Level|
|2 hours after initiation of treatment||< 80%||Increase 30%||2 hours after each dose adjustment 6 hours after initiation of treatment or dose adjustment|
|80% to 120%||None|
|> 120%||Decrease 30%||2 hours after each dose adjustment|
As surgery or delivery may rapidly decrease the AT activity levels, check the AT level just after surgery or delivery. If AT activity level is below 80%, an additional bolus dose may be administered to rapidly restore decreased AT activity level. In such instances, the loading dose formulae in Table 1 should be used, utilizing in the calculation the last available AT activity result. Thereafter, restart the maintenance dose at the same rate of infusion as before the bolus.
Dosage Forms And Strengths
ATryn (recombinant lyophilized powder) is a sterile lyophilized formulation. Each vial of ATryn (recombinant lyophilized powder) contains the potency stated on the label, which is approximately 1750 IU.
Approximately 1750 IU/vial in a sterile white to off-white lyophilized powder for reconstitution.Each carton contains one single dose vial of ATryn (recombinant lyophilized powder) .
The actual potency of ATryn (recombinant lyophilized powder) is stated on the vial label and carton.
Storage and Handling
Store ATryn (recombinant lyophilized powder) refrigerated at between 2-8°C (36-46°F).
Do not use product beyond the expiration date printed on the package. Discard unused portions.
Manufacturer: GTC Biotherapeutics, Inc. Framingham, MA 01702, U.S.A.,. Marketed by: Ovation Pharmaceuticals, Inc. Deerfield, IL 60015, U.S.A., Issued: February 2009.
(1) Patnaik MM, Moll S. Inherited antithrombin deficiency: a review. Haemophilia 2008;14:1229-39.
(3) Edmunds T, Van Patten SM, Pollock J et al. Transgenically produced human antithrombin: structural and functional comparison to human plasma-derived antithrombin. Blood 1998 June 15;91(12):4561-71.
Last reviewed on RxList: 3/10/2009
This monograph has been modified to include the generic and brand name in many instances.
Additional Atryn Information
- Atryn Drug Interactions Center: antithrombin iii, hum recom iv
- Atryn Side Effects Center
- Atryn FDA Approved Prescribing Information including Dosage
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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