Treatment of Addisonian pernicious anaemia.

Prophylaxis and treatment of other macrocytic anaemias due to vitamin B₁₂ deficiency.

Treatment of tobacco amblyopia.

Treatment of Lieber's atrophy.

Posology

The following dosages are suitable for children and adults.

Addisonian pernicious anaemia and other macrocytic anaemias without neurological involvement:

Addisonian pernicious anaemia and other macrocytic anaemias with neurological involvement:

Prophylaxis of macrocytic anaemias associated with vitamin B₁₂ deficiency resulting from gastrectomy, ileal resection, certain ma/absorption states and vegetarianism:

1000 micrograms every two or three months.

Tobacco amblyopia and Leber's optic atrophy:

Method of Administration

Intramuscular injection

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

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 arrhythmias secondary to hypokalaemia during initial therapy have been reported. Plasma potassium should therefore be monitored during this period.

Chloramphenicol

Parenteral chloramphenicol may attenuate the effect of hydroxocobalamin in anaemia.

Oral contraceptives

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.

Pregnancy

Hydroxocobalamin injection should not be used for the treatment of megaloblastic anaemia of pregnancy.

Breast-feeding

Hydroxocobalamin is secreted into breast milk but is unlikely to harm the infant.

Fertility

No data available

Not relevant.

The following adverse reactions are classified by system organ class and ranked under heading of frequency using the following convention:

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 Not known” .

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

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 or search for MHRA Yellow Card in the Google Play or Apple App Store.

Treatment is unlikely to be needed in 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 malabsorption 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.

Distribution

Hydroxocobalamin is extensively bound to specific plasma proteins (transcobalamins); transcobalamin II appears to be involved in the rapid transport of the cobalamins to tissues.

Elimination

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. It is stored in the liver, excreted in the bile, and undergoes enterohepatic recycling; part of a 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.

Sodium dihydrogen orthophosphate

Sodium chloride

Sodium Hydroxide (for pH adjustment)

Hydrochloric Acid (for pH adjustment)

Water for Injections

Not Applicable

2 years

Protect from light. Store below 25° C.

This medicine is supplied in clear 1ml Type I glass ampoules in cartons of 5 or 10.

No special requirements