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XYNTHA

Hemophilia therapy Xyntha® is a recombinant antihemophilic factor (rAHF), also called factor VIII (FVIII), that is manufactured with recombinant DNA technology. Cell lines obtained from genetically engineered Chinese Hamster Ovary secrete the rAHF, which is then purified in a series of chromatography steps and a solvent-detergent viral inactivation step. The final rAHF is comparable with the 90 + 80 kDa form of human coagulation FVIII.¹

Xyntha is available as a sterile, nonpyrogenic, preservative-free, lyophilized powder in single-use vials containing 250, 500, 1000, or 2000 IU. The route of administration is intravenous. Xyntha temporarily replaces FVIII and facilitates effective hemostasis.¹

Indications

Xyntha is indicated for the on-demand treatment and control of episodes of bleeding, for perioperative management, and for prophylaxis to reduce the frequency of episodes of bleeding in adults and children with hemophilia A.¹

Get full prescribing information for Xyntha at MPR

Efficacy

The efficacy of Xyntha as an on-demand treatment in adults and adolescents was established in a randomized crossover study, in which 93% of episodes of bleeding were resolved with 1 or 2 infusions of Xyntha and 5 of 187 bleeds (3%) did not respond. In general, 71% of responses of treated bleeds to Xyntha were rated as “excellent” or “good,” and 24% were rated as “moderate.” In children younger than 12 years, 92% of treated bleeds resolved with 1 to 2 infusions, and 94% of responses of treated bleeds to Xyntha were rated as “excellent” or “good.”²

A study of 30 patients with hemophilia undergoing a surgical procedure evaluated the hemostatic efficacy of Xyntha for perioperative management. The responses of all subjects received investigator ratings of excellent (achieved hemostasis comparable with that expected after similar surgery in a patient without hemophilia) or good (prolonged time to hemostasis, with somewhat increased bleeding compared with that expected after similar surgery in a patient without hemophilia).³

Dosage

The required dose is calculated with the following formula¹:

Required dose = body weight (kg) x desired FVIII rise (IU/dL or % of normal) x 0.5 (IU/dL)

Dosage for routine prophylaxis is as follows¹:

For children younger than 12 years: 25 IU/kg every other day. More frequent or higher doses may be required.
For adults and adolescents 12 years of age or older: 30 IU/kg 3 times weekly.

Dosage for on-demand treatment and control of episodes of bleeding is as follows:¹

Minor bleeding: 20 to 40 IU/dL every 12 to 24 hours for at least 1 day, depending on the severity of the episode of bleeding. Examples include early hemarthrosis and minor muscle or oral bleeds.
Moderate bleeding: 30 to 60 IU/dL every 12 to 24 hours for 3 to 4 days or until adequate local hemostasis is achieved. Examples include bleeding in muscles, bleeding after mild head trauma, and bleeding into the oral cavity
Major bleeding: 60 to 100 IU/dL every 8 to 24 hours until bleeding is resolved. Examples include gastrointestinal, intracranial, intra-abdominal, and intrathoracic bleeding, and bleeding from fractures.

Dosage for perioperative management¹:

Minor surgery: 30 to 60 IU/dL every 12 to 24 hours for 3 to 4 days until adequate local hemostasis is achieved. Examples include minor operations, including tooth extraction. For tooth extraction, a single infusion plus oral antifibrinolytic therapy within 1 hour may be sufficient.
Major surgery: 60 to 100 IU/dL every 8 to 24 hours until threat is resolved or until adequate local hemostasis and wound healing are achieved.

Safety Information

Xyntha is contraindicated in patients who have manifested life-threatening immediate hypersensitivity reactions to the product or any of its components, including hamster proteins. The most common adverse reactions include headache, arthralgia, pyrexia, and cough. The development of inhibitors has been reported following the administration of Xyntha. It is unknown whether Xyntha can cause fetal harm when used during pregnancy, and no information is available regarding the presence of Xyntha in human breast milk.¹

References

1. Package insert – XYNTHA. Pfizer. Revised August 2020. Accessed January 3, 2022.

2. Recht M, Nemes L, Matysiak M, et al. Clinical evaluation of moroctocog alfa (AF-CC), a new generation of B-domain deleted recombinant factor VIII (BDDrFVIII) for treatment of haemophilia A: demonstration of safety, efficacy, and pharmacokinetic equivalence to full-length recombinant factor VIII. Haemophilia. 2009;15(4):869-880. doi:10.1111/j.1365-2516.2009.02027.x

3. Windyga J, Rusen L, Gruppo R, et al. BDDrFVIII (moroctocog alfa [AF-CC]) for surgical haemostasis in patients with haemophilia A: results of a pivotal study. Haemophilia. 2010;16(5):731-739. doi:10.1111/j.1365-2516.2010.02239.x

Reviewed by Hasan Avcu, MD, on 1/3/2022.

Kyle Habet, MD

Kyle Habet, MD, is a physician at Belize International Institute of Neuroscience where he is a member of a multidisciplinary group of healthcare professionals involved in the care of patients with an array of neurological and psychiatric diseases. He is a published author, researcher and instructor of neuroscience and clinical medicine at Washington University of Health and Science.

Hemophilia