Summary of Product Characteristics (SmPC) - Hydroxocobalamin 1000 micrograms/ml solution for injection
1 NAME OF THE MEDICINAL PRODUCT
Hydroxocobalamin 1000 micrograms/ml solution for injection
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each 1 ml ampoule contains 1000 micrograms of hydroxocobalamin (as hydroxocobalamin acetate).
Hydroxocobalamin contains cobalt.
For the full list of excipients, see section 6.1.
3 PHARMACEUTICAL FORM
Solution for injection.
Clear red solution
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Addisonian 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
Posology
Adults and Children
Addisonian pernicious anaemia and other macrocytic anaemias without neurological involvement:
Initially: 250 to 1000mcg on alternate days for one to two weeks, then 250mcg weekly until the blood count is normal. Maintenance: 1000mcg every two to three months.
Addisonian pernicious anaemia and other macrocytic anaemias with neurological involvement:
Initially: 1000mcg on alternate days as long as improvement is occurring Maintenance: 1000mcg every two months.
Prophylaxis of macrocytic anaemia associated with vitamin B12 deficiency resulting from gastrectomy, some malabsorption syndromes and strict vegetarianism:
1000mcg every two to three months.
Tobacco amblyopia and Leber's optic atrophy:
Initially 1000mcg or more daily for two weeks. Then twice weekly as long as improvement is occurring. Maintenance: 1000mcg monthly.
Method of administration:
Intramuscular injection
4.3 Contraindications
Hypersensitivity to any ingredient of the preparation.
Hydroxocobalamin should not be used for treatment of megaloblastic anaemia of pregnancy unless vitamin B12 deficiency has been demonstrated.
4.4 Special warnings and precautions for use
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 10mcg 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 arrhythmias:
Cardiac arrhythmias secondary to hypokalaemia during initial therapy have been reported. Plasma potassium should therefore be monitored during this period.
Reactive thrombocytosis:
Platelet count should be monitored during the first weeks of use in megaloblastic anaemia due to the possible occurrence of reactive thrombocytosis.
Sodium
This medicinal product contains less than 1 mmol sodium (23 mg) per dose, that is to say essentially 'sodium-free'
4.5 Interaction with other medicinal products and other forms of interaction
Chloramphenicol
Chloramphenicol-treated patients may respond poorly to Hydroxocobalamin.
Oral contraceptives
Serum concentrations of hydroxocobalamin may be lowered by oral contraceptives but this interaction is unlikely to have clinical significance.
Antimetabolites and most antibiotics invalidate vitamin B12 assays by microbiological techniques.
4.6 Fertility, pregnancy and lactation
Pregnancy
Hydroxocobalamin should not be used for the treatment of megaloblastic anaemia of pregnancy unless vitamin B12 deficiency has been demonstrated.
Breast-feeding
Hydroxocobalamin is secreted into breast milk but this is unlikely to harm the infant, and may be beneficial if the mother and infant are vitamin B12 deficient.
Fertility
No data available
4.7 Effects on ability to drive and use machines
None stated
4.8 Undesirable effects
The following effects have been reported and are listed below by body system:
Blood and lymphatic system disorders
Reactive thrombocytosis can occur during the first weeks of use in megaloblastic anaemia.
Cardiovascular disorders:
Arrhythmias secondary to hypokalaemia.
Disorders of the immune system:
Hypersensitivity reactions including skin reactions (e.g. rash, itching) and exceptionally anaphylaxis.
Gastro intestinal disorders:
Nausea, vomiting, diarrhoea.
General disorders:
Fever, chills, hot flushing, dizziness, malaise, pain. Injection site reactions including injection site pain, injection site erythema, injection site pruritus, injection site induration, and injection site swelling.
Neurological disorders:
Headache, sensory abnormalities such as paraesthesia.
Tremor.
Renal and urinary disorders:
Chromaturia
Skin and subcutaneous tissue disorders:
Acneiform and bullous eruptions.
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 Yellow Card Scheme Website www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
4.9 Overdose
Treatment is unlikely to be needed in cases of overdosage.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antianaemic preparations -Vitamin B12
ATC code: B03BA03
5.2 Pharmacokinetic properties
Distribution
Vitamin B12 is extensively bound to specific plasma proteins called transcobalamins; transcobalamin II appears to be involved in the rapid transport of the cobalamins to tissues.
Elimination
Vitamin B12 is stored in the liver, excreted in the bile, and undergoes extensive enterohepatic recycling; part of an administered dose is excreted in the urine, most of it in the first 8 hours; urinary excretion, however, accounts for only a small fraction in the reduction of total body stores acquired by dietary means. Vitamin B12 diffuses across the placenta and also appears in breast milk.
An intramuscular injection of hydroxocobalamin produces higher serum levels than the same dose of cyanocobalamin, and these levels are well maintained. After injection of hydroxocobalamin, 90% of a 100 microgram dose and 30% of a 1000 microgram dose are retained.
5.3 Preclinical safety data
None stated
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Sodium chloride, acetic acid (E260), Water for Injections
6.2 Incompatibilities
None
6.3 Shelf life
15 months
6.4 Special precautions for storage
Do not store above 25°C. Do not refrigerate or freeze.
6.5 Nature and contents of container
Clear, one-point cut (OPC) glass Type 1 ampoules packed in cartons of 5 x 1ml ampoules
6.6 Special precautions for disposal
Not applicable
7 MARKETING AUTHORISATION HOLDER
Strandhaven Ltd t/a Somex Pharma
600 High Road,
Ilford, Essex,
IG3 8BS
UK
8 MARKETING AUTHORISATION NUMBER(S)
PL 15764/0141
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE
AUTHORISATION
07/08/2026
10 DATE OF REVISION OF THE TEXT
07/08/2026