Hemofil M

Hemofil M^® is indicated for the treatment and prophylaxis of bleeding in patients with haemophilia A (congenital factor VIII deficiency).

Despite the von Willebrand factor content and functionality of this product there are no data from clinical trials supporting use in von Willebrand disease.

This product may be used in the management of acquired factor VIII deficiency.

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.

On demand treatment

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 one ml of normal human plasma. The calculation of the required dosage of factor VIII is based on the empirical finding that 1 International 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:

Prophylaxis

For long term prophylaxis against bleeding in patients with severe haemophilia A, the usual doses are 20 to 40 IU of factor VIII per kg body weight at intervals of 2 to 3 days. In some cases, especially in younger patients, shorter dosage intervals or higher doses may be necessary.

Continuous infusion

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.

Paediatric population

There are insufficient data from clinical trials to recommend the use of Hemofil M® in children less than 6 years of age.

As the posology is adjusted to the clinical outcome of the above mentioned conditions, the posology in children, by body weight, is not considered to be different to that of adults.

Method of administration

As with any intravenous protein product, allergic type hypersensitivity reactions are possible.

Cases of recurrent inhibitor (low titre) have been observed after switching from one factor VIII product to another in previously treated patients with more than 100 exposure days who have a previous history of inhibitor development. Therefore, it is recommended to monitor patients carefully for inhibitor occurrence following any product switch.

Appropriate vaccination (hepatitis A and B) should be considered for patients in regular receipt of human plasma-derived factor VIII products.

It is strongly recommended that every time that Hemofil M^® is administered to a patient, the name and batch number of the product are recorded in order to maintain a link between the patient and the batch of the product.

Sodium content

The residual content of sodium in Hemofil M^®, arising from the manufacturing process, does not exceed 23 mg per vial in the 250, 500 and 1000 IU presentations, and 34.5 mg per vial in the 1500 IU presentation. This is equivalent to 1.15% and 1.72% respectively of the recommended maximum daily intake of sodium for an adult. However, depending on the body weight of the patient and the posology, the patient may receive more than one vial.

Hemofil M^® has no or negligible influence on the ability to drive and use machines.

Hypersensitivity or allergic reactions (which may include angioedema, burning and stinging at the infusion site, chills, flushing, generalised urticaria, headache, hives, hypotension, lethargy, nausea, restlessness, tachycardia, tightness of the chest, tingling, vomiting, wheezing) have been observed infrequently, and may in some cases progress to severe anaphylaxis (including shock).

On rare occasions, fever has been observed.

The adverse drug reactions reported are summarised and categorised according to the MedDRA system organ class in the table below. Within each frequency grouping, undesirable effects are presented in order of decreasing of seriousness. Frequency has been determined using the following criteria:

- very common: >1/10 infusions

- common: >1/100 to <1/10 infusions

- uncommon: >1/1,000 to <1/100 infusions

- rare: >1/10,000 to <1/1,000 infusions

- very rare: <1/10,000, not known (cannot be estimated from the available data.)

Patients with haemophilia A may develop neutralising antibodies to factor VIII.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme, website: https://yellowcard.mhra.gov.uk.

No case of overdose has been reported.

Pharmacotherapeutic Group: Antihaemorrhagics: blood coagulation factor VIII. ATC code: B02BD02.

In Hemofil M^®, factor VIII is presented as a complex with von Willebrand factor.

The factor VIII/von Willebrand factor complex consists of two molecules (factor VIII and von Willebrand factor) with different physiological functions.

When infused into a haemophiliac patient, factor VIII binds to von Willebrand factor in the patient's circulation.

Activated factor VIII acts as a cofactor for activated factor IX, accelerating the conversion of factor X to activated factor X. Activated factor X converts prothrombin into thrombin. Thrombin then converts fibrinogen into fibrin and a clot can be formed.

Haemophilia A is a sex-linked hereditary disorder of blood coagulation due to decreased levels of factor VIII and results in profuse bleeding into joints, muscles or internal organs, either spontaneously or as a result of accidental or surgical trauma. By replacement therapy the plasma levels of factor VIII are increased, thereby enabling a temporary correction of the factor deficiency and correction of the bleeding tendencies.

In addition to its role as a factor VIII protecting protein, von Willebrand mediates platelet adhesion to sites of vascular injury and plays a role in platelet aggregation.

There are insufficient data from clinical trials in children less than 6 years of age.

Data on Immune Tolerance Induction (ITI) have been collected in paediatric and adult patients with haemophilia A who have developed inhibitors to FVIII. The 57 patients from a retrospective study and 14 patients from prospective studies included a broad spectrum of primary and rescue ITI patients with varying prognoses for achieving immune tolerance. Data show that Hemofil M has been used to induce immune tolerance. In patients where tolerance was achieved, bleeding could be prevented or controlled on either prophylactic or on-demand therapy with a FVIII concentrate.

Plasma factor VIII activity decreases by a two-phase exponential decay.

The half-life of human factor VIII obtained in the clinical trial carried out with Hemofil M^® is 14.18 ± 2.55 hours and the "in vivo" recovery is 105.5 ± 18.5%, which is equivalent to approximately 2.1 ± 0.4 IU/dl per IU/kg administered (determinations performed following chromogenic method). Additional pharmacokinetic parameters are: mean residence time (MRT) 19.9 ± 4.1 h, area under curve (AUC) 19.3 ± 3.8 IU h/ml and clearance 2.6 ± 0.6 ml/h/kg.

Human plasma coagulation factor VIII (active ingredient for Hemofil M^®) is a normal constituent of the human plasma and acts like the endogenous factor VIII. Single dose toxicity testing is of no relevance since higher doses result in overloading.

Repeated dose toxicity testing in animals is impracticable due to interference with developing antibodies to heterologous protein.

Hemofil M^® must not be mixed with other medicinal products.

Only the provided infusion set should be used because treatment failure can occur as a consequence of factor VIII adsorption to the internal surfaces of some infusion equipment.

Do not use after the expiry date shown on the label.

Left-over product must never be kept for later use, nor stored in a refrigerator.

To prepare the solution:

1. Warm the vial and syringe but not above 30°C.

2. Attach plunger to syringe containing diluent.

3. Remove filter from packaging. Remove cap from syringe tip and attach syringe to filter.

4. Remove vial adaptor from packaging and attach to syringe and filter.

5. Remove cap from vial and wipe stopper with swabs provided.

6. Pierce vial stopper with adaptor needle.

7. Transfer all diluent from syringe to vial.

8. Gently shake vial until all product is dissolved. As with other parenteral solutions, do not use if product is not properly dissolved or particles are visible.

9. Briefly separate the syringe/filter from vial/adaptor, to release the vacuum.

10. Invert vial and aspirate solution into syringe.

11. Prepare injection site, separate syringe and inject product using the butterfly needle provided. Injection rate should be 3 ml/min into a vein and never more than 10 ml/min to avoid vasomotor reactions.

Do not re-use administration sets.

Any unused product or waste material should be disposed of in accordance with local requirements.

The solution should be clear or slightly opalescent. Do not use solutions that are cloudy or have deposits.

Reconstituted products should be inspected visually for particulate matter and discolouration prior to administration.