Treatment should be initiated under the supervision of a physician experienced in the treatment of haemophilia.
Posology
The dosage and duration of the substitution therapy depend on the severity of the factor VIII deficiency, on the location and extent of the bleeding and on the patient’s clinical condition.
The number of units of factor VIII administered is expressed in International Units (IU), which are related to the current WHO standard for factor VIII products. Factor VIII activity in plasma is expressed either as a percentage (relative to normal human plasma) or in International Units (relative to an International Standard for factor VIII in plasma).
One International Unit (IU) of factor VIII activity is equivalent to that quantity of factor VIII in oneml of normal human plasma. The calculation of the required dosage of factor VIII is based on the empirical finding that 1International Unit (IU) factor VIII per kg body weight raises the plasma factor VIII activity by 2.1 ± 0.4% of normal activity. The required dosage is determined using the following formula:
Required units = body weight (kg) ´ desired factor VIII rise (%) (IU/dl) ´ 0.5
The amount to be administered and the frequency of administration should always be oriented to the clinical effectiveness in the individual case.
In the case of the following haemorrhagic events, the factor VIII activity should not fall below the given plasma activity level (in % of normal or IU/dl) in the corresponding period. The following table can be used to guide dosing in bleeding episodes and surgery:
|
Degree of haemorrhage/ Type of surgical procedure |
Factor VIII level required (%) (IU/dl) |
Frequency of doses (hours)/
Duration of therapy (days) |
|
|
|
|
|
Haemorrhage
|
|
|
|
Early haemarthrosis, muscle bleeding or oral bleeding
|
20 ‑ 40 |
Repeat every 12 to 24hours. At least 1day, until the bleeding episode as indicated by pain is resolved or healing is achieved.
|
|
More extensive haemarthrosis, muscle bleeding or haematoma
|
30 ‑ 60 |
Repeat infusion every 12‑24hours for 3‑4days or more until pain and acute disability are resolved.
|
|
Life threatening haemorrhages
|
60 ‑ 100 |
Repeat infusion every 8 to 24hours until threat is resolved.
|
|
|
|
|
|
Surgery
|
|
|
|
Minor
including tooth extraction |
30 ‑ 60 |
Every 24hours, at least 1day, until healing is achieved.
|
|
Major |
80 ‑ 100
(pre-and postoperative) |
Repeat infusion every 8 ‑ 24hours until adequate wound healing, then therapy for at least another 7days to maintain a factor VIII activity of 30% to 60% (IU/dl).
|
During the course of treatment, appropriate determination of factor VIII levels is advised to guide the dose to be administered and the frequency of repeated infusions. In the case of major surgical interventions in particular, precise monitoring of the substitution therapy by means of coagulation analysis (plasma factor VIII activity) is indispensable. Individual patients may vary in their response to factor VIII, achieving different levels of in vivo recovery and demonstrating different half-lives.
For long term prophylaxis against bleeding in patients with severe haemophilia A, the usual doses are 20 to 40IU of factor VIII per kg body weight at intervals of 2 to 3days. In some cases, especially in younger patients, shorter dosage intervals or higher doses may be necessary.
Patients should be monitored for the development of factor VIII inhibitors. If the expected factor VIII activity plasma levels are not attained, or if bleeding is not controlled with an appropriate dose, an assay should be performed to determine if a factor VIII inhibitor is present. In patients with high levels of inhibitor, factor VIII therapy may not be effective and other therapeutic options should be considered. Management of such patients should be directed by physicians with experience in the care of patients with haemophilia. See also section 4.4.
Paediatric population
There are insufficient data from clinical trials to recommend the use of Fanhdi in children less than 6 years of age.
Method of administration
The product should be administered via the intravenous route. Fanhdi should be administered at a flow rate of no more than 10 ml/min.
For instructions on reconstitution of the medicinal product before administration, see section 6.6.