Recommended Dosage of Pyridoxine (Vitamin B6) for Treatment and Prevention of Deficiency
For treatment of vitamin B6 deficiency, oral doses of 50-100 mg daily for one to two weeks are recommended, while prevention requires at least 1.5 mg daily in enteral nutrition or 4-6 mg daily in parenteral nutrition. 1
Dosage Recommendations by Clinical Scenario
General Treatment of Deficiency
- Oral supplements of 50-100 mg daily for one to two weeks are safe and effective for treating deficiency from chronic poor dietary intake 1
- When treating deficiency, pyridoxal phosphate (PLP) levels respond to intake, reflecting liver stores and plateauing in 6-10 days 1
- Standard over-the-counter supplementation typically provides 50 mg per tablet (2500% of daily value) 2
Prevention of Deficiency
- Enteral nutrition should deliver at least 1.5 mg pyridoxine per day in 1500 kcal (Grade A recommendation) 1
- Parenteral nutrition should deliver 4-6 mg pyridoxine per day (Grade B recommendation) 1
- Normal dietary requirements are typically 15 micrograms/g dietary protein, with RDAs ranging between 1.3-2.2 mg/day for adults 3
Special Clinical Scenarios
- For isoniazid overdose-induced seizures: 1 g of pyridoxine for each gram of isoniazid ingested, then 1 g IM or IV every 30 min up to maximum 5 g 1
- For ethylene glycol poisoning: 50 mg IV every 6 hours 1
- For patients taking tuberculosis medications: 25-50 mg/day, increasing to 100 mg/day only if peripheral neuropathy develops 4
- For hemodialysis patients: 10 mg/day of supplemental pyridoxine hydrochloride 5
- For peritoneal dialysis and non-dialyzed renal failure patients: 5 mg/day of supplemental pyridoxine hydrochloride 5
Monitoring and Assessment
- Vitamin B6 status should be determined by measuring plasma pyridoxal phosphate (PLP) levels 1
- Normal values of plasma PLP are 5-50 mg/L (20-200 nmol/L) 1
- In seriously ill patients or in the presence of inflammation, red cell PLP should be measured instead of plasma levels 1
Toxicity Considerations
- No adverse effects have been reported from high food intake of pyridoxine 1
- However, large oral supplemental doses (>500 mg/day) have resulted in various side effects 1
- Negative effects have been related to prolonged intakes of 300 mg/day 1
- Long-term doses as low as 100 mg/day have been associated with Lhermitte signs (suggesting spinal cord effects) 1
- The No Observed Adverse Effect Level (NOAEL) is 100 mg/day 1
- The European Food Safety Authority recommends an upper tolerable intake level of 100 mg/day for adults over 19 years 4
High-Risk Populations
- Populations at greatest risk for deficiency include: 1
- Alcoholics
- Renal dialysis patients
- Elderly individuals
- Post-operative patients
- Those with infections or critical illness
- Pregnant women
- People taking medications that inhibit vitamin B6 activity (isoniazid, penicillamine, anti-cancer drugs, corticosteroids, anticonvulsants)
Clinical Pearls
- Elderly individuals may be more susceptible to vitamin B6 toxicity due to age-related changes in metabolism 4
- Patients with renal impairment may have reduced clearance of vitamin B6, potentially increasing toxicity risk 4
- Caution is advised for pregnant women taking high-dose vitamin B6 supplements due to potential adverse effects on fetal proprioceptive neuron function 6
- While some studies suggest vitamin B6 may help with carpal tunnel syndrome at doses of 100-200 mg daily for 12 weeks, evidence for cognitive benefits in older adults is lacking 7, 8