Pyridoxine
VITAMIN B6
What it isVitamin B6 converted to the enzyme cofactor pyridoxal phosphate; deficiency and nausea of pregnancy.
Why this oneIt is the specific antidote for isoniazid-induced seizures and treats pyridoxine-dependent epilepsy.
What limits it⚑ Chronic high-dose supplementation can cause an irreversible sensory neuropathy—a vitamin that is neurotoxic in excess.
FDA-approved for
- pyridoxine deficiency
- nausea of pregnancy
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Pyridoxine deficiency — inadequate dietary intake | Adult | 10-20 mg IM/IV QD x3 weeks | Follow with oral multivitamin containing 2-5 mg pyridoxine QD for several weeks | 20 mg/day (deficiency regimen) |
| Vitamin B6 dependency syndrome (e.g., B6-dependent convulsions or B6-responsive anemia) | Adult | Up to 600 mg/day therapeutic | 30 mg QD for life (maintenance) | 600 mg/day |
| Drug-induced deficiency (isoniazid or oral contraceptives) | Adult | 100 mg QD x3 weeks | 30 mg QD maintenance | 100 mg/day (initial regimen) |
| Isoniazid poisoning (>10 g ingested) | Adult | Pyridoxine dose equal to amount of INH ingested: 4 g IV, then 1 g IM q30min | Total dose equal to INH ingested | Equal to INH dose ingested |
Renal Undefined (note: product contains aluminum — toxicity risk with prolonged parenteral use in impaired kidney function)
Hepatic Undefined
Instructions
- Administer intramuscularly or intravenously (parenteral route when oral not feasible or GI absorption impaired)
- Correct poor dietary habits; prescribe adequate well-balanced diet
- Inspect visually for particulate matter and discoloration before use
Cautions
- Aluminum content — may reach toxic levels with prolonged parenteral administration in renal impairment; premature neonates particularly at risk (CNS and bone toxicity at >4-5 mcg/kg/day parenteral aluminum)
- Antagonizes levodopa — do not give supplements to patients on levodopa alone; patients on levodopa should avoid >5 mg/day supplemental pyridoxine (may be used with carbidopa/levodopa)
- Single pyridoxine deficiency is rare — expect multiple vitamin deficiency with inadequate diet
- Women on oral contraceptives may have increased pyridoxine requirements
- Safety and effectiveness in children not established
Adverse reactions
- Paresthesia
- Somnolence
- Low serum folic acid levels
Pregnancy Pregnancy Category A — requirement appears increased during pregnancy; sometimes of value in treating nausea and vomiting of pregnancy
Lactation Need for pyridoxine increased during lactation; not known whether excreted in human milk — exercise caution
NO BOXED WARNINGS
Principal riskIrreversible sensory neuropathy at chronic high dose
Classes and tags
Clinical profile
Active metabolites
Mechanism of action: Pyridoxine ballicule
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Memory aids: mascots and interaction avatars
charge → peripheral neuropathy in deficiency and also with chronic supratherapeutic dosing
Beef sticks (B6 soundalike) contain plenty of vitamin B6