IntramuscularPernicious or macrocytic anaemiaAdult: Patient without neurological involvement: Initially, 0.25-1 mg on alternate days for 1-2 weeks, then 0.25 mg weekly until blood count is normal. Maintenance: 1 mg every 2 or 3 months. With neurological involvement: Initially, 1 mg on alternate days, continued as long as improvement occurs. Maintenance: 1 mg every 2 months.
Child: Same as adult dose.
IntramuscularProphylaxis of macrocytic anaemia caused by vitamin B12 deficiencyAdult: 1 mg every 2 or 3 months.
Child: Same as adult dose.
IntramuscularVitamin B12 deficiencyAdult: Initially, 30 mcg once daily for 5-10 days followed by 100-200 mcg monthly.
Child: 100 mcg once daily for ≥2 weeks to a total of 1,000-5,000 mcg. Maintenance: 30-50 mcg monthly.
IntramuscularLeber's optic atrophy, Tobacco amblyopiaAdult: Initially, 1 mg daily for 2 weeks followed by 1 mg twice weekly for as long as improvement is maintained, then 1 mg every 1-3 months thereafter.
IntravenousCyanide poisoningAdult: Initially, 5 g given as a single infusion over 15 minutes; a 2nd dose of 5 g may be infused over 15 minutes to 2 hours as needed, depending on the severity of the toxicity.
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Intravenous: Add 100 mL or 200 mL of NaCl 0.9% inj to a vial labelled as containing 2.5 g or 5 g, respectively, to provide a solution containing 25 mg/mL. Lactated Ringer’s inj or dextrose 5% inj may be used if NaCl 0.9% is unavailable.
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Incompatible with ascorbic acid, blood products, Na nitrite, Na thiosulfate, diazepam, dobutamine, fentanyl, nitroglycerin, pentobarbital, propofol, thiopental.
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Children. Pregnancy and lactation.
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Significant: Hypertension, photosensitivity.
Cardiac disorders: Arrhythmias secondary to hypokalaemia.
Gastrointestinal disorders: Gastrointestinal disturbances.
General disorders and administration site conditions: Fever, chills, malaise, inj site reactions (e.g. pain, erythema, pruritus, induration, swelling and necrosis).
Immune system disorders: Rarely, allergic hypersensitivity reactions, anaphylaxis.
Nervous system disorders: Dizziness, tremor, headache, paraesthesia.
Renal and urinary disorders: Chromaturia.
Skin and subcutaneous tissue disorders: Acneiform and bullous eruptions, rash and itching.
Vascular disorders: Increased blood pressure, hot flushing.
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This drug may cause photosensitivity, avoid direct exposure to sunlight.
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Monitor vitamin B12, haematocrit, Hb, reticulocyte count, RBC count, folate and Fe levels, serum K and platelet counts; blood pressure and heart rate (during treatment for cyanide poisoning). Perform sensitivity test prior to administration.
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Reduced absorption with neomycin, aminosalicylic acid, histamine H2-antagonists, omeprazole, colchicine. Decreases serum concentration with oral contraceptives. Effect on anaemia may be attenuated by parenteral chloramphenicol.
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Interferes with the determination of certain parameters using colorimetric methods (e.g. clinical chemistry, haematology, coagulation, urine parameters). Methotrexate, pyrimethamine, and most anti-infectives invalidate diagnostic microbiologic blood assays for hydroxocobalamin.
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Description:
Mechanism of Action: Hydroxocobalamin (vitamin B12a) is a precursor to cyanocobalamin (vitamin B12). Cyanocobalamin acts as a coenzyme for various metabolic functions that are essential in cell replication and haematopoiesis. In the presence of cyanide, each hydroxocobalamin molecule can bind one cyanide ion by displacing it for the hydroxo ligand linked to the trivalent cobalt ion.
Pharmacokinetics:
Distribution: Distributed into the liver, bone marrow and other tissues. Crosses the placenta and enters breast milk. Plasma protein binding: Extensively bound to transcobalamins.
Metabolism: Converted to coenzyme form in the liver. Undergoes extensive enterohepatic recycling.
Excretion: IM: Via bile; some in urine. IV: Via urine (50-60%). Elimination half-life: 26-31 hours (IV).
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Store between 20-25°C. Protect from light.
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B03BA03 - hydroxocobalamin ; Belongs to the class of vitamin B12 (cyanocobalamin and analogues). Used in the treatment of anemia.
V03AB33 - hydroxocobalamin ; Belongs to the class of antidotes. Used in the management of cyanide poisoning.
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Anon. Hydroxocobalamin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 06/04/2016. Buckingham R (ed). Vitamin B12 Substances. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 06/04/2016. Cyanokit Injection, Powder, Lyophilized, for Solution (Meridian Medical Technologies, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 08/04/2011. Hydroxocobalamin Acetate Injection, Solution (Watson Laboratories, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 31/08/2011. Joint Formulary Committee. Hydroxocobalamin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 06/04/2016. McEvoy GK, Snow EK, Miller J et al (eds). Vitamin B12. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 06/04/2016.
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