Big B

• Prevention & Treatment of Deficiencies
• Thiamine (B₁): Dry/wet beriberi, Wernicke’s encephalopathy, Korsakoff psychosis, chronic alcoholism
• Pyridoxine (B₆): Rare deficiency states, sideroblastic anemia, neonatal pyridoxine‑responsive seizures
• Cobalamin (B₁₂): Pernicious and megaloblastic anemia, dietary insufficiency, malabsorption syndromes (e.g., post‑gastrectomy)
• Neurological Disorders
• Thiamine: Refeeding syndrome, ataxia in chronic alcoholism
• Pyridoxine: Diabetic/alcoholic neuropathy, infantile seizures
• Cobalamin: Peripheral neuropathy, subacute combined degeneration, optic neuropathy
• Homocysteine Regulation
• B‑complex synergy reduces elevated homocysteine—supportive in cardiovascular risk reduction
• Pregnancy & Growth
• Supports fetal neurodevelopment, red blood cell formation, and addresses infant nutritional needs

Oral / IM / IV

• Adults:
• B₁: 1.1–1.2 mg/day (RDA); 50–100 mg/day oral; 200–500 mg IV/IM daily for acute Wernicke’s
• B₆: 1.3–1.7 mg/day (RDA); 50–100 mg/day for neuropathy; up to 30 mg/kg/day for neonatal seizures
• B₁₂: 2.4 µg/day (RDA); 1,000 µg IM weekly until correction, then monthly maintenance; high‑dose oral alternative
• Pediatrics:
• Dose by age/weight (e.g., infants 0.2–0.5 mg/day B₁/B₆; B₁₂ dosing per deficiency severity)
• Elderly & Special Populations:
• Adults dosing recommended; monitor absorption in malabsorption or polypharmacy
• Administration Tips:
• Oral types with meals
• IV/IM reserved for malabsorption or neurologic emergencies

Thiamine is phospho‑activated to TPP, crucial for energy metabolism and neuronal function. Pyridoxine becomes PLP, supporting amino acid metabolism, neurotransmitter synthesis, erythropoiesis, and homocysteine clearance. Cobalamin forms methyl‑ and adenosylcobalamin, essential for DNA synthesis, myelin stability, methylation processes, and neurologic health. Together, they maintain metabolic, hematologic, and neurologic integrity.

• Absorption:
  B₁/B₆ via intestinal transport; B₁₂ requires intrinsic factor in terminal ileum (passive absorption at high oral doses)
• Distribution:
  B₁₂ stored in liver; B₁/B₆ circulate freely and are quickly depleted
• Metabolism:
  B₁/B₆ converted to TPP and PLP; B₁₂ transformed into active cobalamin forms
• Excretion:
  Excess eliminated through urine; B₁₂ partly conserved via enterohepatic cycling
• Half‑Life:
  B₁: ~1–2 weeks
  B₆: ~15–20 days
  B₁₂: Days to weeks

• Pregnancy:
  Safe at RDA levels and important for fetal development. High-dose usage requires medical oversight.
• Breastfeeding:
  Vitamins are excreted into breast milk; supplementation contributes to infant nutrition.
• Cautions:
  High-dose pyridoxine (>100 mg/day) requires monitoring for neurologic effects.

• Primary Class: Water‑soluble vitamins
• Subclass: B‑complex essential nutrients
• Pharmacologic Category: Cofactor precursors and hematinic agents

• Hypersensitivity to B₁, B₆, or B₁₂
• Sensory neuropathy with high-dose B₆
• Unexplained seizure worsening with pyridoxine

• Anaphylaxis Risk: Rare with IV/IM thiamine
• Neuropathy: High-dose B₆ (>200 mg/day) may cause sensory neuropathy
• Seizure Risk: Monitor seizure control with pyridoxine therapy
• Hypokalemia: Possible with rapid B₁₂ therapy—monitor electrolytes

• Common: Mild GI upset (B₆), injection site discomfort, flushing (rare)
• Serious:
• IV thiamine: Rare anaphylaxis
• High-dose B₆: Peripheral sensory neuropathy
• High-dose B₁₂: Rare rash, dizziness
• Onset: Injection reactions may occur within minutes; neuropathy develops over weeks–months

• Levodopa: B₆ increases metabolism—may reduce motor effects
• Isoniazid: Depletes B₆—supplementation recommended
• Metformin/PPIs: May reduce B₁₂ absorption—monitor levels
• Phenytoin/Phenobarbital: Reduce B-complex levels—supplementation required
• Alcohol: Impairs all three vitamins’ absorption and increases excretion

• Migraine Management: High-dose riboflavin accepted as prophylaxis
• Malnutrition/Refeeding: Standard use of parenteral thiamine in high-risk patients
• B₆ Monitoring: Safety concern prompting alert on neuropathy risk over 200 mg/day

• Temperature: 15–25 °C (59–77 °F)
• Light: Protect (especially riboflavin) from UV
• Humidity: Store in dry, sealed container
• Handling: Shake liquid forms; store injectable vials upright, inspect before use
• Protection: Keep out of children’s reach; no refrigeration required unless specified