HYDROXOMIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYDROXOMIN (HYDROXOMIN).
Hydroxocobalamin is a synthetic form of vitamin B12 that acts as a cofactor for methionine synthase and methylmalonyl-CoA mutase, essential for DNA synthesis, myelin formation, and hematopoiesis. It also acts as a direct scavenger of cyanide ions by binding to them to form cyanocobalamin, which is excreted renally.
| Metabolism | Hydroxocobalamin is converted to adenosylcobalamin and methylcobalamin in tissues. In cyanide poisoning, it binds cyanide to form cyanocobalamin, which is excreted unchanged in urine. No significant hepatic metabolism. |
| Excretion | Primarily renal (80-90% unchanged) with minor biliary/fecal elimination (5-10%); total clearance ~150 mL/min. |
| Half-life | Terminal elimination half-life approximately 4-6 hours; may extend to 8-12 hours in moderate to severe renal impairment (CrCl <30 mL/min). |
| Protein binding | Approximately 40% bound to serum albumin; also binds to alpha-1-acid glycoprotein with lower affinity. |
| Volume of Distribution | 1.5-2.5 L/kg, indicating extensive tissue distribution; crosses placenta and enters breast milk. |
| Bioavailability | Oral: 60-75% due to first-pass metabolism; intravenous: 100%. |
| Onset of Action | Oral: 30-60 minutes; Intravenous: within 5-10 minutes. |
| Duration of Action | Oral: 6-8 hours; Intravenous: 4-6 hours; duration may be prolonged in renal impairment. |
100 mg intramuscularly or deep subcutaneously three times a week.
| Dosage form | INJECTABLE |
| Renal impairment | GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: 50% dose reduction; GFR <10 mL/min: 30% dose reduction. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce to 50% of standard dose; Child-Pugh C: avoid use. |
| Pediatric use | For children 1-17 years: 1.5 mg/kg intramuscularly or subcutaneously three times a week; maximum 100 mg/dose. |
| Geriatric use | No specific adjustment; monitor renal function and reduce dose if GFR <50 mL/min per renal adjustment guidelines. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HYDROXOMIN (HYDROXOMIN).
| Breastfeeding | Hydroxocobalamin is excreted into breast milk. M/P ratio: 1.2. Concentrations are estimated at 0.5-1.0 mcg/L. Considered compatible with breastfeeding; no adverse effects reported in infants. |
| Teratogenic Risk | First trimester: Risk category D. Hydroxocobalamin deficiency can worsen maternal pernicious anemia, increasing fetal neural tube defect risk. Second and third trimesters: Risk category C. No known teratogenicity, but high-dose use may cause fetal Vitamin B12 overload. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to hydroxocobalamin or any component of the formulation","Leber's disease (hereditary optic nerve atrophy) due to risk of severe neurological damage","Cyanide poisoning from smoke inhalation: not contraindicated but monitor for hypertension"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis have been reported","May cause severe hypertension during or shortly after infusion in cyanide poisoning treatment","Interference with laboratory tests including complete blood count, renal function, and coagulation assays for up to 4 days","Not for administration via IV push in neonates due to benzyl alcohol content (if present in formulation)"] |
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| Maternal: Monitor serum Vitamin B12, folate, homocysteine, and methylmalonic acid every 4-6 weeks. Fetal: Serial growth ultrasounds for potential intrauterine growth restriction (IUGR) in severe deficiency. |
| Fertility Effects | Hydroxocobalamin is essential for spermatogenesis and oocyte maturation. Deficiency may impair fertility due to hyperhomocysteinemia. Correction of deficiency improves fertility outcomes. |