Cyanocobalamin (Vitamin B12)
Cyanocobalamin (Vitamin B12) is a water-soluble vitamin essential for normal cellular function, particularly in rapidly dividing cells. - **Primary Use**: Parenteral treatment of Vitamin B12 deficiency. - **Common Causes of Deficiency**: Exocrine pancreatic insufficiency (EPI), inflammatory bowel disease (IBD), and other malabsorptive gastrointestinal diseases. - **Species Specifics**: - **Dogs & Cats**: High prevalence of deficiency secondary to GI/pancreatic disease. Giant Schnauzers (and other breeds like Beagles and Border Collies) may have a genetic defect affecting cobalamin-intrinsic factor complex absorption (Imerslund-Gräsbeck syndrome). - **Ruminants**: Deficiency is often secondary to dietary **cobalt** deficiency, as rumen microflora require cobalt to synthesize B12. > **Clinical Pearl**: Unlike humans, dogs and cats lack the cobalamin-binding protein TC1. This means they can rapidly deplete their B12 stores in just 1-2 months during states of malabsorption, whereas humans take 1-2 years.
Mecanismo: Vitamin B12 acts as a crucial coenzyme for two major enzymatic pathways: 1. **Methylmalonyl-CoA mutase**: Converts methylmalonyl-CoA → succinyl-CoA. (Deficiency leads to methylmalonic acidemia/aciduria). 2. **Methionine synthase**: Catalyzes the remethylation of homocysteine → methionine, which is intimately linked with **folate** metabolism. - Required for normal cell growth, nucleoprotein and myelin synthesis, amino acid metabolism, and erythropoiesis. - **Note**: B12 deficiency can cause a functional folate deficiency. Unlike humans, macrocytic anemias do not appear to be a significant component of cobalamin deficiency in dogs or cats.
Dosificación por especie
- Treatment of vitamin B12 deficiency associated with cobalt deficiency (Lambs) · 100 micrograms (total dose) · injection · once weekly
- Treatment of vitamin B12 deficiency associated with cobalt deficiency (Adult sheep) · 300 micrograms (total dose) · injection · once weekly
- Treatment of vitamin B12 deficiency associated with cobalt deficiency · 0.2-0.4 mL of a 5000 micrograms/mL injection (1000-2000 micrograms) · IM or SC · weekly intervals if necessary
- Cobalamin deficiency in cats with IBD · 250-500 micrograms (total dose per cat) · SC · once per week for 6 weeks, then every 1-2 months
- Adjunctive treatment of idiopathic hepatic lipidosis · 250 micrograms (total dose) · SC · once per week · 6 weeks · Recheck serum B12 level in one to two weeks after cessation of treatment as some cats may need repeated administration.
- Cobalamin deficiency associated with GI disease · 150-250 micrograms (total dose) · SC · once weekly for 6 weeks, then every 14 days for 6 weeks, then one dose 30 days later · Initial 16-week protocol · Based on body size. Recheck serum cobalamin concentration one month after last dose.
- Cobalamin deficiency associated with exocrine pancreatic insufficiency · 100-250 micrograms (total dose) · SC · once weekly · Periodically assess cobalamin and folate levels.
Vías de administración
Contraindicaciones
- Hypersensitivity to cyanocobalamin or hydroxocobalamin
- Known hypersensitivity to cobalt or cobalamin
Efectos adversos
- Pain at injection site (uncommon)
- Anaphylaxis (rarely reported in humans)
- Pain or stinging at the injection site
- Mild allergic reactions (rare)
Interacciones farmacológicas
- Antibiotics · Concurrent use can cause falsely low serum or red blood cell cobalamin values if a microbiologic method assay is used.
- Omeprazole · May decrease oral absorption of Vitamin B12 by altering gastric pH · minor
Monitorización
- Serum cobalamin levels
- Serum folate status (both before and after treatment)
- Clinical signs associated with deficiency (weight loss, poor haircoat, vomiting, diarrhea)
- CBC (baseline and ongoing if abnormal)
- Serum cobalamin (Vitamin B12) levels
- Serum folate levels
- Clinical signs of gastrointestinal disease (weight gain, fecal consistency)
Sobredosis
Cyanocobalamin is very safe. An inadvertent overdose given via SC or IM injection is unlikely to cause significant morbidity.
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