Hydroxocobalamin

What it is used for

• Pernicious anemia, both uncomplicated and accompanied by nervous system involvement.
• Dietary deficiency of Vitamin B 12, occurring in strict vegetarians and in their breast-fed infants. (Isolated vitamin B 12 deficiency is very rare).
• Malabsorption of vitamin B 12, resulting from structural or functional damage to the stomach, where intrinsic factor is secreted or to the ileum, where intrinsic factor facilitates vitamin B 12 absorption. These conditions include tropical sprue, and nontropical sprue (idiopathic steatorrhea, gluten-induced enteropathy). Folate deficiency in these patients is usually more severe than vitamin B 12 deficiency.
• Inadequate secretion of intrinsic factor, resulting from lesions that destroy the gastric mucosa (ingestion of corrosives, extensive neoplasia), and a number of conditions associated with a variable degree of gastric atrophy (such as multiple sclerosis, certain endocrine disorders, iron deficiency, and subtotal gastrectomy). Total gastrectomy always produces vitamin B 12 deficiency. Structural lesions leading to vitamin B 12 deficiency include regional ileitis, ileal resections, malignancies, etc.
• Competition for Vitamin B 12 by intestinal parasites or bacteria. The fish tapeworm (Diphyllobothrium latum) absorbs huge quantities of vitamin B 12 and infested patients often have associated gastric atrophy. The blind-loop syndrome may produce deficiency of Vitamin B 12 or folate.
• Inadequate utilization of vitamin B 12. This may occur if antimetabolites for the vitamin are employed in the treatment of neoplasia.
• For the Schilling Test.

How to take it

Protect from light.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Hydroxocobalamin injection should be given only intramuscularly.

In patients with Addisonian Pernicious Anemia, parenteral therapy with vitamin B 12 is the recommended method of treatment and will be required for the remainder of the patient’s life. Oral therapy is not dependable. In other patients with vitamin B 12 deficiency, the duration of therapy and route of administration will depend upon the cause and whether or not it is reversible.

Confirmatory diagnostic studies should be performed prior to initiating therapy, if possible, and the patient should be followed with appropriate studies to demonstrate hematologic improvement (Hgb, hematocrit, RBC, reticulocyte count). A diagnostic trial utilizing physiologic doses of vitamin B 12 (1 mcg daily) and observing daily reticulocyte counts after establishing a baseline may also be performed. The observation of reticulocytosis which usually occurs between the third and tenth day of therapy confirms the diagnosis of vitamin B 12 deficiency.

In seriously ill patients it may be advisable to administer both vitamin B 12 and folic acid while awaiting the results of distinguishing laboratory studies. It is not necessary to withhold vitamin B 12 therapy until the precise cause of B 12 deficiency is established since absorption studies can be performed at any time.

Serum potassium should be closely observed the first 48 hours and potassium should be administered if necessary.

Side effects, and when to stop

Mild transient diarrhea, itching, transitory exanthema, feeling of swelling of entire body, and anaphylaxis.

A few patients may experience pain after injection of hydroxocobalamin.

To report SUSPECTED ADVERSE EVENTS, contact Actavis at 1-800-272-5525 or FDA at 1-800-FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.

Warnings

Avoid the intravenous route.

Folic acid is not a substitute for vitamin B 12 although it may improve vitamin B 12 deficient megaloblastic anemia. Exclusive use of folic acid in treating vitamin B 12 deficient megaloblastic anemia could result in progressive and irreversible neurologic damage.

Blunted or impeded therapeutic response to vitamin B 12 may be due to such conditions as infection, uremia, drugs having bone marrow suppressant properties such as chloramphenicol, and concurrent iron or folic acid deficiency.

Storing it

Store at 20°-25°C (68°-77°F). PROTECT FROM LIGHT.

Literature revised: January 2017

Manufactured by: Hikma Farmaceutica (Portugal) S.A. 2705-906 Terrugem SNT, Portugal Distributed by: Actavis Pharma, Inc. Parsippany, NJ 07054 USA

PIN229-WAT/2

Contraindication

Hypersensitivity to any component of this medication.

General

The validity of diagnostic vitamin B 12 or folic acid blood assays could be compromised by medications, and this should be considered before relying on such tests for therapy.

Vitamin B 12 is not a substitute for folic acid and since it might improve folic acid deficient megaloblastic anemia, indiscriminate use of vitamin B 12 could mask the true diagnosis.

Hypokalemia and thrombocytosis could occur upon conversion of severe megaloblastic to normal erythropoiesis with B 12 therapy. Therefore, serum potassium levels and the platelet count should be monitored carefully during therapy.

Vitamin B 12 deficiency may suppress the signs of polycythemia vera. Treatment with vitamin B 12 may unmask this condition.