Xyntha for hemophilia

Last updated May 30, 2023, by Marisa Wexler, MS

✅ Fact-checked by Joana Carvalho, PhD

What is Xyntha for hemophilia?

Xyntha (moroctocog alfa) is a recombinant, or man-made, clotting factor therapy approved to treat and prevent bleeds in people with hemophilia A.

It was originally developed by Wyeth Pharmaceuticals and is now marketed by Pfizer, which acquired Wyeth in 2009. 

How does Xyntha work?

In hemophilia A, mutations impair the production or functionality of clotting factor VIII (FVIII), a protein that plays a key role in blood clotting, resulting in prolonged and excessive bleeding.

Xyntha contains a man-made (recombinant) version of this protein that can be administered to people with hemophilia A to make up for the missing FVIII. The therapy, given intravenously or into the vein, works to restore normal blood clotting.

The version of FVIII used in Xyntha is manufactured using a genetically-engineered Chinese hamster ovary (CHO) cell line. 

Who can take Xyntha?

Xyntha was first approved by the U.S. Food and Drug Administration (FDA) in 2008 as an on-demand treatment to control bleeding episodes and to manage bleeds occurring during surgery. In 2020, its approval was extended to include its use as a routine prophylactic treatment to prevent and lower the frequency of bleeding episodes.

Its current indications cover its use in both adults and children in the U.S. with hemophilia A.

The therapy also is approved in Europe, where it is marketed under the brand name ReFacto AF, for the treatment and prevention of bleeding episodes in hemophilia A patients of all ages.

Who should not take Xyntha?

Xyntha should not be used by anyone who has experienced a serious allergic reaction to the therapy or any of its components, including hamster proteins. 

The therapy is not indicated for the treatment of von Willebrand’s disease, another blood disorder.

How is Xyntha administered?

Xyntha is available in single-use vials containing 250, 500, 1,000, or 2,000 international units (IU) of FVIII. It must be reconstituted, or diluted, in a supplied liquid solution before it can be administered into the vein. Administration usually takes several minutes, depending on a patient’s comfort level.

The appropriate dose and duration of treatment will be determined by a healthcare professional based on the patient’s age, body weight, and clinical condition, as well as on the type of bleed, bleeding severity, and degree of FVIII deficiency.

For routine prophylaxis, or preventive treatment, Xyntha’s recommended starting dosage is:

  • 30 IU per kilogram of body weight, three times weekly, for patients ages 12 and older
  • 25 IU per kilogram of body weight, every other day, for children younger than 12.

The dosing and frequency of prophylactic injections may be altered based on a patient’s response. According to the therapy’s label, higher doses or more frequent administrations may be required in children younger than 12, due to the higher speed at which the medication is cleared from the body among these pediatric patients.

For on-demand treatment, Xyntha is recommended to be given to maintain FVIII activity levels at:

  • 20 to 40 IU/dL, with dosing every 12-24 hours for at least one day, depending on bleeding severity, in the case of minor bleeds
  • 30 to 60 IU/dL, with dosing every 12-24 hours for 3–4 days or until bleeding is under control, in the case of moderate bleeds
  • 60 to 100 IU/dL, with dosing every 8-24 hours until bleeding is resolved, in the case of major bleeds.

For minor surgical procedures, Xyntha should be given every 12-24 hours for 3-4 days or until bleeding is under control. The aim is to maintain FVIII activity levels at 30 to 60 IU/dL.

For major surgical procedures, Xyntha should be given every 8-24 hours until bleeding is under control and healing is achieved, to maintain FVIII activity levels at 60 to 100 IU/dL.

Xyntha in clinical trials

The safety and efficacy of Xyntha as an on-demand, prophylactic, and perioperative — given around the time of surgery — treatment for hemophilia A were demonstrated in three clinical trials involving a total of 174 previously-treated patients.

On-demand treatment

To test the therapy for on-demand use, a clinical trial enrolled 94 people with hemophilia A, ages 12 and older. All were receiving Xyntha as a routine prophylactic treatment. During the study, Xyntha was used as an on-demand treatment to manage bleeds occurring in 53 of these patients.

The vast majority (93%) of these bleeds resolved after just one or two infusions of Xyntha. Among all 187 treated bleeds, the efficacy of Xyntha was rated as good or excellent in 71%. Another 24% were rated as “moderate,” while the rest were either not rated or showed no response to treatment. 

In another study that enrolled 50 children ages 12 and younger, 38 were given Xyntha for on-demand management of 562 bleeding episodes. The majority of these bleeds (92%) resolved after one or two infusions of Xyntha. The therapy’s efficacy was rated as good or excellent in nearly all cases (94%). 

Use in surgery

In another trial, Xyntha was used for perioperative treatment to control bleeding during surgery in 25 people with hemophilia A. In all of these surgeries, the efficacy of the therapy was rated as either excellent or good.


Routine prophylactic treatment with Xyntha was evaluated in 94 hemophilia A patients ages 12 and older, as well as in eight children younger than 12.

Annual bleeding rates decreased by 89% among older patients once they switched from on-demand treatment to prophylaxis with Xyntha. Nearly half of patients (45%) reported no bleeding with routine prophylaxis.

Findings in younger patients were similar: bleeding rates dropped by a mean of 97%, and half of the children were bleed-free while on preventive treatment.

Common side effects of Xyntha

The most common side effects of Xyntha reported in clinical trials include:

  • headache
  • joint pain
  • fever
  • cough.

Allergic reactions

Allergic reactions, including serious reactions known as anaphylaxis, may occur in patients receiving Xyntha. Symptoms of an allergic reaction may include an itchy rash or hives, wheezing, and chest tightness. If an allergic reaction occurs, Xyntha should be stopped immediately and appropriate treatment given to manage the reaction.


In some patients, the immune system can mistake the clotting protein in Xyntha for an infectious threat and produce neutralizing antibodies, called inhibitors, against it. Patients should be regularly monitored for FVIII activity and inhibitors, and inhibitor levels should be checked if treatment does not elicit the expected response.

Use in pregnancy and breastfeeding

There are no available data on the use of Xyntha during pregnancy or while breastfeeding. Therefore, it’s not known if the therapy can be harmful to a developing fetus, pass to breast milk, or have a negative effect on breastfed infants.

In these situations, patients and their care teams should evaluate the potential risks and benefits of using Xyntha to make an individualized decision on to continuing or stopping treatment.


Hemophilia News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.