This information is intended for use by health professionals

1. Name of the medicinal product

Hydroxocobalamin 1mg in 1ml, solution for injection

2. Qualitative and quantitative composition

Hydroxocobalamin (as acetate) 1.0 mg/ml

For excipients, see Section 6.1.

3. Pharmaceutical form

Solution for injection

4. Clinical particulars
4.1 Therapeutic indications

Pernicious anaemia. Prophylaxis and treatment of other macrocytic anaemias associated with Vitamin B12 deficiency. Tobacco amblyopia and Leber's optic atrophy.

4.2 Posology and method of administration

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

4.3 Contraindications

Hypersensitivity to any ingredient in the preparation

4.4 Special warnings and precautions for use

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.

4.5 Interaction with other medicinal products and other forms of interaction

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.

4.6 Pregnancy and lactation

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.

4.7 Effects on ability to drive and use machines

None known.

4.8 Undesirable effects

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

Initial hypokalaemia

Neurological disorders:

Headache, paraesthesia, tremor.

Cardiac disorders:

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:

Chromaturia.

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).

4.9 Overdose

Treatment is unlikely to be required in the case of overdose.

5. Pharmacological properties
5.1 Pharmacodynamic properties

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.

5.2 Pharmacokinetic properties

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.

5.3 Preclinical safety data

There is no additional information relevant to the prescriber.

6. Pharmaceutical particulars
6.1 List of excipients

Acetic acid

Sodium chloride

Sodium hydroxide

Water for injections

6.2 Incompatibilities

None known.

6.3 Shelf life

18 months.

6.4 Special precautions for storage

Do not store above 25°C.

Keep container in the outer carton.

6.5 Nature and contents of container

1ml clear glass (Ph. Eur. Type I) one-point-cut ampoules containing 1ml solution for injection.

Pack size: 5 ampoules per carton.

6.6 Special precautions for disposal and other handling

None.

7. Marketing authorisation holder

Accord Healthcare Limited

Sage House

319 Pinner Road

North Harrow

Middlesex

HA1 4HF

United Kingdom

8. Marketing authorisation number(s)

PL 20075/0691

9. Date of first authorisation/renewal of the authorisation

17/03/2009

10. Date of revision of the text

25/08/2017