|HYDROXOCOBALAMIN (VITAMIN B12 ALPHA)
Hydrobexan, Hydroxo-12, LA-12
Classifications: vitamin b12 antidote; Therapeutic: vitamin supplement; antidote
Pregnancy Category: A (C if >RDA)
1000 mcg/mL injection
Cobalamin derivative similar to cyanocobalamin (vitamin B12). More slowly absorbed from injection site than cyanocobalamin and may be taken up by liver in larger quantities. Essential
for normal cell growth, cell reproduction maturation of RBCs, myelin synthesis, and believed to be involved in protein synthesis.
Effective in vitamin B12 deficiency that results in megaloblastic anemia.
Treatment of vitamin B12 deficiency.
Cyanide poisoning and tobacco amblyopia.
History of sensitivity to vitamin B12, other cobalamins, or cobalt; indiscriminate use in folic acid deficiency.
Pregnancy [category A, category C (parenteral)], lactation, children.
Route & Dosage
|Vitamin B12 Deficiency
Adult: IM 30 mcg/d for 510 d and then 100200 mcg/mo or 1000 mcg qod until remission and then 1000 mcg/mo
Child: IM 100 mcg doses to a total of 15 mg over 2 wk and then 3050 mcg/mo
- Give deep into a large muscle.
Interactions Drug: Chloramphenicol
may interfere with therapeutic response to hydroxocobalamin.
Widely distributed; principally stored in liver, kidneys, and adrenals; crosses placenta. Metabolism:
Converted in tissues to active coenzymes; enterohepatically cycled. Elimination:
5095% of doses ≥100 mcg are excreted in urine in 48 h; excreted
in breast milk.
Assessment & Drug Effects
- Monitor for therapeutic effectiveness: Response to drug therapy is usually dramatic, occurring within 48 h. Effectiveness
is measured by laboratory values and improvement in manifestations of vitamin B12 deficiency. Characteristically, reticulocyte concentration rises in 34 d, peaks in 58 d, and then gradually
declines as erythrocyte count and hemoglobin rise to normal levels (in 46 wk).
- Lab tests: Prior to therapy determine reticulocyte and erythrocyte counts, Hgb, Hct, vitamin B12, and serum folate levels; repeated 57 d after start of therapy and at regular intervals during therapy.
- Obtain a careful history of sensitivities. Sensitization can take as long as 8 y to develop.
- Monitor potassium levels during the first 48 h, particularly in patients with Addisonian pernicious anemia or megaloblastic
anemia. Conversion to normal erythropoiesis increases erythrocyte potassium requirement and can result in severe hypokalemia
and sudden death.
- Monitor vital signs in patients with cardiac disease and in those receiving parenteral cyanocobalamin, and be alert to symptoms
of pulmonary edema; generally occur early in therapy.
- Note: Some patients experience mild pain at injection site after administration.
- Monitor bowel function. Bowel regularity is essential for consistent absorption of oral preparations.
- Note: Smokers appear to have increased requirements for vitamin B12.
Patient & Family Education
- Notify physician of any intercurrent disease or infection. Increased dosage may be required.
- Note: It is imperative to understand that drug therapy must be continued throughout life for pernicious anemia to prevent irreversible
- Neurologic damage is considered irreversible if there is no improvement after 11? y of adequate therapy.
- Dietary deficiency of vitamin B12 has been observed in strict vegetarians (vegans) and their breast-fed infants as well as in the elderly.