HYDROXOCOBALAMIN

Posology Dosage - Adults (all ages) and children:

Addisonian pernicious anaemia and other macrocytic anaemias without neurological involvement. Initially: 250 micrograms to 1mg intramuscularly on alternate days for one or two weeks, then 250 micrograms weekly until blood count is normal.

Maintenance: 1mg every two or three months. Addisonian pernicious anaemia and other macrocytic anaemias with neurological involvement. Initially, 1mg on alternate days as long as improvement is occurring. Maintenance: 1mg every 2 months.

Prophylaxis of macrocytic anaemia associated with Vitamin B12 deficiency resulting from gastrectomy, ileal resection, some malabsorption syndromes and strict vegetarianism 1mg every two to three months. Tobacco amblyopia and Leber’s optic atrophy Initially, 1mg or more daily by intramuscular injection for 2 weeks.

Then twice weekly as long as improvement is occurring. Maintenance: 1mg monthly. Method of administration Intramuscular injection.

The following undesirable effects may occur with the use of hydroxocobalamin in the following frequencies: Very common (> 1/10) Common (> 1/100, <1/10) Uncommon (> 1/1,000, <1/100) Rare (> 1/10,000, <1/1,000) Very rare (<1/10,000) Not known (cannot be estimated from the available data).

There are no modern clinical studies available that can be used to determine the frequency of undesirable effects. Therefore, all the undesirable effects listed are classed as “frequency unknown”.

The following effects have been reported and are listed below by body system:

System organ class Frequency Undesirable effects Blood and lymphatic system disorders Not Known Reactive thrombocytosis can occur during the first weeks of use in megaloblastic anaemia. Immune system disorders Not Known Hypersensitivity reactions including rash; itching; exanthema.

Antibodies to hydroxocobalamin- transcobalamin II complex have developed during hydroxocobalamin therapy. Anaphylaxis Metabolism and nutrition disorders Not Known Initial hypokalaemia Nervous system disorders Not Known Headache, paraesthesia, tremor.

Cardiac disorders Not Known Arrhythmias secondary to hypokalaemia. Gastrointestinal Not Known Nausea, vomiting, disorders diarrhoea. General disorders and administration site conditions Not Known Fever, chills, hot flushes; dizziness; malaise; pain; Injection site reactions including injection site pain, injection site erythema, injection site pruritus, injection site` induration, and injection site swelling.

Skin and subcutaneous tissue disorders Not Known Acneiform and bullous eruptions Renal and urinary disorders Not Known Chromaturia Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.

The dosage schemes given above are usually satisfactory, but regular examination of the blood is advisable. If megaloblastic anaemia fails to respond to hydroxocobalamin, folate metabolism should be investigated. Doses in excess of 10 micrograms daily may produce a haematological response in patients with folate deficiency.

Indiscriminate administration may mask the true diagnosis. The haematological and neurological state should be monitored regularly to ensure adequacy of therapy. Cardiac arrythmias secondary to hypokalaemia during initial therapy have been reported.

Plasma potassium should therefore be monitored during this period. Platelet count should be monitored during the first weeks of use in megaloblastic anaemia due to the possible occurrence of reactive thrombocytosis. Hydroxocobalamin solution for injection contains sodium This medicine contains less than 1 mmol sodium (23 mg) per ampule, that is to say essentially ‘sodium-free’.

1. Hydroxocobalamin should not be used for the treatment of megaloblastic anaemia of pregnancy unless vitamin B12 deficiency has been demonstrated.