Vitamin B6 (Pyridoxine) Dosing for a 65kg Male
For a 65kg male not on isoniazid therapy, routine vitamin B6 supplementation is not recommended, as dietary intake is typically sufficient and supplementation above 100 mg/day carries risk of peripheral neuropathy. 1
Context-Dependent Dosing Algorithm
If Patient is NOT on Isoniazid Therapy:
- No supplementation needed - dietary sources provide adequate B6 for healthy adults 1
- If supplementation is desired for other clinical reasons, limit to ≤50 mg/day to avoid neurotoxicity risk 1, 2
- Doses of 100-300 mg/day have been associated with occasional reports of peripheral neuropathy 2
If Patient IS on Isoniazid Therapy:
Standard prophylactic dosing: 25-50 mg/day 3, 4
This applies to all patients at high risk of isoniazid-induced peripheral neuropathy, including:
- Patients with diabetes mellitus 3, 4
- Patients with alcoholism or malnutrition 3, 4
- Patients with chronic renal failure 3, 4
- Patients of advanced age 3, 4
- HIV-infected persons 3, 4
- Pregnant women and breastfeeding mothers 3, 4
If peripheral neuropathy develops: increase to 100 mg/day 3, 4
If Patient is on Hemodialysis:
- 10 mg/day supplementation is recommended, as pyridoxine is removed during dialysis and dietary intake is typically insufficient 5
- This lower dose corrects deficiency without approaching toxic thresholds 5
Safety Thresholds and Toxicity Risk
The therapeutic window for pyridoxine is narrow and weight-independent:
- Safe prophylactic range: 10-50 mg/day for most clinical scenarios 3, 4, 5, 1
- Therapeutic range for established neuropathy: 100 mg/day 3, 4
- Toxicity threshold: >100-300 mg/day chronically causes sensory neuropathy 2, 6
- Definite neurotoxicity: ≥1000 mg/day 2
Critical Clinical Pitfalls
Do not exceed 50 mg/day without specific indication (such as isoniazid therapy or established deficiency), as the evidence for benefit is lacking and risk of harm increases 1
Monitor for sensory neuropathy symptoms in any patient taking >50 mg/day chronically, including paresthesias, numbness, or ataxia 2, 7
Isoniazid creates functional B6 deficiency even with adequate dietary intake due to competitive metabolic inhibition, making supplementation essential in at-risk populations 4, 8
Weight-based dosing is not used for pyridoxine supplementation in adults - the 25-50 mg/day dose applies regardless of body weight 3, 4