RUBRAMIN PC
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RUBRAMIN PC (RUBRAMIN PC).
Cyanocobalamin (vitamin B12) is essential for DNA synthesis, myelin formation, and hematopoiesis. It acts as a cofactor for methionine synthase and methylmalonyl-CoA mutase.
| Metabolism | Cyanocobalamin is metabolized in the liver via conversion to active coenzymes (methylcobalamin and adenosylcobalamin). |
| Excretion | Renal: 50-98% as unchanged drug via glomerular filtration and tubular secretion; biliary/fecal: <1% |
| Half-life | Terminal elimination half-life: 6-7 hours in normal renal function; prolonged to 7-10 hours in elderly; significantly extended in renal impairment (up to 80 hours in ESRD), requiring dose adjustment |
| Protein binding | 90-95% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | Vd: 0.15-0.25 L/kg; reflects limited extravascular distribution; lower Vd in elderly and renal impairment |
| Bioavailability | Oral: 80-100% (tablets and solution); Rectal: 80-90% |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 15-30 minutes; Intravenous: <5 minutes |
| Duration of Action | Duration: 4-6 hours for analgesic effect; clinical effect correlates with serum concentration >15 mcg/mL |
1000 mcg intramuscularly once daily for 5-7 days, then 1000 mcg intramuscularly once weekly for 4 weeks, followed by 1000 mcg intramuscularly once monthly.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment. However, monitor serum potassium levels in patients with renal insufficiency due to potential for hyperkalemia with cyanocobalamin administration. |
| Liver impairment | No specific dose adjustment recommended for hepatic impairment based on Child-Pugh score. |
| Pediatric use | For cyanocobalamin deficiency: 100 mcg intramuscularly once daily for 1 week, then 100 mcg intramuscularly once weekly for 4 weeks, followed by 100 mcg intramuscularly once monthly. For congenital pernicious anemia: 30-50 mcg intramuscularly once daily for 2 weeks, then 100 mcg intramuscularly once monthly. |
| Geriatric use | No specific dose adjustment required. However, monitor for hypokalemia and thrombocytosis in elderly patients receiving high doses. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RUBRAMIN PC (RUBRAMIN PC).
| Breastfeeding | Cyanocobalamin is excreted into human milk in amounts that reflect maternal intake (M/P ratio not determined). At usual doses, no adverse effects on nursing infant expected. Monitor infant for signs of hypersensitivity. |
| Teratogenic Risk | No adequate studies in pregnant women. Cyanocobalamin (vitamin B12) is essential for fetal development. Teratogenic risk is low at recommended doses; deficiency is associated with neural tube defects. Avoid excessive doses due to potential unknown effects. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to cyanocobalamin or any component","Leber's disease (hereditary optic nerve atrophy)","Severe hypokalemia (relative)"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis have been reported.","Folic acid may mask vitamin B12 deficiency; ensure adequate B12 levels before folic acid supplementation.","Use with caution in patients with Leber's disease (optic atrophy).","Monitor serum potassium levels during initial therapy due to risk of hypokalemia."] |
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| Monitor maternal serum B12 levels, complete blood count (CBC) with reticulocyte count during treatment. For fetal monitoring, standard prenatal care including ultrasound for neural tube defects if deficiency present. |
| Fertility Effects | No known adverse effects on fertility. B12 deficiency may impair fertility; supplementation may improve outcomes. |