Hypersensitivity Reactions: Allergic type hypersensitivity reactions, including anaphylaxis, are possible with XYNTHA. Inform patients of the early signs or symptoms of hypersensitivity reactions (including hives [rash with itching], generalized urticaria, chest tightness, wheezing, and hypotension) and anaphylaxis. Discontinue XYNTHA if hypersensitivity symptoms occur and administer appropriate emergency treatment.
XYNTHA contains trace amounts of hamster proteins. Patients treated with this product may develop hypersensitivity to these non-human mammalian proteins.
Neutralizing Antibodies: Inhibitors have been reported following administration of XYNTHA. Monitor patients for the development of factor VIII inhibitors by appropriate clinical observations and laboratory tests. If expected factor VIII activity plasma levels are not attained, or if bleeding is not controlled with an appropriate dose, perform an assay that measures factor VIII inhibitor concentration to determine if a factor VIII inhibitor is present [see Monitoring: Laboratory Tests as follows].
Monitoring Laboratory Tests: Use individual factor VIII values for recovery and, if clinically indicated, other pharmacokinetic characteristics to guide dosing and administration.
Monitor plasma factor VIII activity levels by the one-stage clotting assay to confirm that adequate factor VIII levels have been achieved and are maintained, when clinically indicated [see Dosage & Administration].
Monitor for development of factor VIII inhibitors. Perform assay to determine if factor VIII inhibitor is present when expected factor VIII activity plasma levels are not attained, or when bleeding is not controlled with the expected dose of XYNTHA. Use Bethesda Units (BU) to titer inhibitors.
Use in Pregnancy & Lactation: Pregnancy: Pregnancy Category C: Animal reproduction studies have not been conducted with XYNTHA. It is not known whether XYNTHA can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. XYNTHA should be given to a pregnant woman only if clinically indicated.
Labor and Delivery: There is no information available on the effect of factor VIII replacement therapy on labor and delivery. XYNTHA should be used only if clinically indicated.
Nursing Mothers: It is not known whether this drug is excreted into human milk. Because many drugs are excreted into human milk, caution should be exercised if XYNTHA is administered to nursing mothers. XYNTHA should be given to nursing mothers only if clinically indicated.
Use in Children: In the completed open label safety and efficacy study of XYNTHA (n=94), 17 adolescent subjects 12 to <16 years of age with severe or moderately severe hemophilia A (FVIII:C ≤ 2%), who were previously treated with at least 150 EDs to FVIII products, received XYNTHA for on-demand and follow-up treatment. The median dose per infusion was 47 IU/kg (min-max: 24-74) and the median exposure per subject was 6 days (min-max: 1-26).
Of the 17 subjects < 16 yrs of age who received at least 1 dose of XYNTHA, 10 subjects had bleeding episodes during the study. Among the 10 subjects with response assessments, a total of 66 bleeding episodes were treated with on-demand infusions of XYNTHA. The majority of the bleeding episodes (63/66 or 95.5%) resolved with 1 or 2 infusions. Thirty-eight (38) of 66 bleeding episodes (57.6%) were rated excellent or good in their response to initial treatment, 24 (36.4%) were rated as moderate and 4 (6.1%) were not rated.
Additional data are available from a safety and efficacy study of XYNTHA in children < 6 years of age with moderately severe or severe hemophilia A (FVIII:C ≤ 2%) and with at least 20 prior EDs to FVIII products. In this study subjects received XYNTHA for on-demand and follow-up treatment of bleeding episodes. The median dose per infusion was 28 IU/kg and the median exposure per subject was 16 days.
Of the 27 subjects < 6 years of age who received at least 1 dose of XYNTHA, 25 had bleeding episodes during the study. Among the 24 subjects with response assessments there were 493 bleeds. The majority of the bleeding episodes (462/493 or 93.7%) resolved with 1 or 2 infusions. Subjects rated the outcomes of infusions on a pre-specified four (4) point hemostatic efficacy scale. Of 493 bleeding episodes treated with XYNTHA, 468 (94.9%) were rated excellent or good in their response to initial treatment and 22 (4.5%) were rated as moderate.
In comparison to the pharmacokinetic parameters reported in adults, children have shorter half-lives, larger volumes of distribution and lower recovery of factor VIII after XYNTHA administration. The clearance (based on per kg body weight) is approximately 40% higher in children. Higher or more frequent doses may be required to account for the observed differences in pharmacokinetic parameters. [see Pharmacology under Actions].
Use in Elderly: Clinical studies of XYNTHA did not include subjects aged 65 and over. In general, dose selection for an elderly patient should be individualized.