- hydroxocobalamin acetate
POM: Prescription only medicine
POM: Prescription only medicine
This information is intended for use by health professionals
Hydroxocobalamin 1mg in 1ml, solution for injection
Hydroxocobalamin (as acetate)
For excipients, see Section 6.1.
Solution for injection
Pernicious anaemia. Prophylaxis and treatment of other macrocytic anaemias associated with Vitamin B12 deficiency. Tobacco amblyopia and Leber's optic atrophy.
Method of administration: Intramuscular injection.
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 continues.
Maintenance: 1mg every 2 months.
Prophylaxis of macrocytic anaemia associated with Vitamin B12 deficiency resulting from gastrectomy, some malabsorption syndromes and strict vegetarianism
1mg every two to three months
Tobacco amblyopia and Leber's optic atrophy
Initially, 1mg daily for 2 weeks, then 1mg twice weekly until no further improvement
Maintenance: 1mg every one to three months
Hypersensitivity to any ingredient in the preparation
It is advisable to confirm the diagnosis of Vitamin B12 deficiency before giving hydroxocobalamin; regular monitoring of the blood is recommended.
If megaloblastic anaemia fails to respond, 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.
Cardiac arrythmias secondary to hypokalaemia during initial therapy have been reported. Plasma potassium should therefore be monitored during this period.
Parenteral chloramphenicol may attenuate the effect of hydroxocobalamin in anaemia.
The serum concentration of hydroxocobalamin may be lowered.
The above interactions are unlikely to be of clinical significance but should be taken into account when performing assays for blood concentrations.
Vitamin B12 assays by microbiological techniques are invalidated by antimetabolites and most antibiotics.
Hydroxocobalamin injection should not be used for the treatment of megaloblastic anaemia of pregnancy.
Hydroxocobalamin is secreted into breast milk but is unlikely to harm the infant.
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”.
Blood and lymphatic system disorders
Reactive thrombocytosis can occur during the first weeks of use in megaloblastic anaemia.
Immune system disorders:
Hypersensitivity reactions including rash; itching; exanthema; anaphylaxis. Antibodies to hydroxocobalamin-transcobalamin II complex have developed during hydroxocobalamin therapy.
Metabolism and nutrition disorders
Headache, paraesthesia, tremor.
Arrhythmias secondary to hypokalaemia.
Gastro intestinal disorders:
Nausea, vomiting, diarrhoea.
General and administration site disorders: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:
Acneiform and bullous eruptions
Renal and urinary disorders:
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 the Yellow Card Scheme (Website: www.mhra.gov.uk/yellowcard).
Treatment is unlikely to be required in the case of overdose.
Pharmacotherapeutic group: Antianaemic preparations – Vitamin B12. ATC code: B03BA03
Hydroxocobalamin is used in the treatment and prevention of Vitamin B12 deficiency. For adults, the daily requirement of Vitamin B12 is probably about 1 to 2 micrograms and this amount is present in most normal diets. However, Vitamin B12 only occurs in animal products, not in vegetables, and therefore strict vegetarian or vegan diets that exclude dairy products may provide an inadequate amount, although a deficiency may not be apparent for many years.
Deficiency is more likely in patients with malabasorption syndromes or metabolic disorders, nitrous-oxide induced megalobastosis, or following gastrectomy or extensive ileal resection. Deficiency leads to megaloblastic anaemias and demyelination and other neurological damage.
On oral intake, Vitamin B12 substances bind to intrinsic factor, a glycoprotein secreted by the gastric mucosa, and are then actively absorbed from the gastrointestinal tract. A specific anaemia known as pernicious anaemia develops in patients with an absence of intrinsic factor. Absorption is also impaired in patients with disease or abnormality of the gut.
Treatment usually results in rapid haematological improvement and a striking clinical response. However, neurological symptoms respond more slowly.
Hydroxocobalamin is extensively bound to specific plasma proteins (transcobalamins); transcobalamin II appears to be involved in the rapid transport of the cobalamins to tissues. Hydroxocobalamin is stored in the liver, excreted in the bile, and undergoes extensive enterohepatic recycling; part of the dose is excreted in the urine, most of it in the first 8 hours. Hydroxocobalamin diffuses across the placenta and also appears in breast milk. Hydroxocobalamin is better retained than cyanocobalamin; 90% of a 100 microgram dose and 30% of a 1000 microgram dose are retained, a range believed to be sufficient for body requirements for 2 to 10 months.
There is no additional information relevant to the prescriber.
Water for injections
Do not store above 25°C.
Keep container in the outer carton.
1ml colourless glass (Ph. Eur. Type I) ampoules containing 1ml solution for injection.
Pack size: 5 ampoules per carton.
Accord Healthcare Limited
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Mckenzie House, Bury Street, Ruislip, Middlesex, HA4 7TL
+44 (0)1895 627 480
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