Recombinant factor VIIa
- Aust Prescr 1999;22:95-8
- 1 August 1999
- DOI: 10.18773/austprescr.1999.079
Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
NovoSeven (Novo Nordisk)
vials containing 1.2 mg, 2.4 mg and 4.8 mg for reconstitution
Approved indication: haemophilia
Australian Medicines Handbook Section 7.4
Patients with haemophilia lack clotting factor VIII or IX. This increases the risk of having a severe haemorrhage after minor injury. To control bleeding the patient is given clotting factors, e.g. a factor VIII concentrate. Over time, some patients will develop antibodies to the clotting factors. These inhibitors can make haemostasis difficult to achieve. Recombinant factor VIIa can circumvent this problem because it activates the extrinsic pathway to coagulation. (Factors VIII and IX are in the intrinsic pathway.)
The new product is genetically engineered. It is almost completely identical to human factor VIIa.
Recombinant factor VIIa is given by slow intravenous injection. It has a half-life of approximately 3 hours, which corresponds to the initial dosage interval. The dose interval is then adjusted according to the clinical response. In bleeding episodes, a dose can be given every 2 hours until control is achieved. After major surgery patients may need to be treated for up to 3 weeks.
The product has been tested in 141 males who had a total of 308 bleeds. It was effective in most cases, but patients can still die from haemorrhagic complications.
The serious adverse events which have occurred in clinical trials include pulmonary embolism and other thrombotic events, disseminated intravascular coagulation, renal failure and shock. More common adverse events include fever, hypertension and headache. Allergic reactions including anaphylaxis can also occur. Two patients have developed antibodies to factor VII after treatment.