Pyridoxine Dosing in Tuberculosis Treatment
For patients undergoing tuberculosis treatment with isoniazid, pyridoxine (vitamin B6) should be administered at a dose of 25-50 mg daily for prevention of peripheral neuropathy, with an increase to 100 mg daily if neuropathy develops despite prophylaxis. 1, 2
Standard Dosing Recommendations
- Preventive dose: 25-50 mg daily for all patients at risk of neuropathy
- Treatment dose: 100 mg daily for patients who develop peripheral neuropathy
Risk Factors Requiring Pyridoxine Supplementation
Pyridoxine supplementation is particularly important for patients with the following risk factors:
- Pregnancy
- Breastfeeding infants
- HIV infection
- Diabetes mellitus
- Alcoholism
- Malnutrition
- Chronic renal failure
- Advanced age 1, 2
Administration Guidelines
- Pyridoxine should be given concurrently with isoniazid from the start of TB treatment
- Supplementation should continue for the entire duration of isoniazid therapy
- The medication can be administered as a separate tablet or as part of a vitamin B complex preparation 2
Clinical Considerations
Mechanism of Isoniazid-Induced Neuropathy
Isoniazid competitively inhibits the action of pyridoxine in metabolic functions, particularly affecting protein metabolism and neurological pathways. This interference with pyridoxine metabolism can lead to peripheral neuropathy, which typically presents as a sensory neuropathy but can also have motor manifestations 3, 4.
Signs and Symptoms of Peripheral Neuropathy
- Paresthesia (tingling, burning sensations)
- Numbness in extremities
- Motor weakness (in severe cases)
- Loss of deep tendon reflexes 3
Monitoring Recommendations
- Regular assessment of neurological symptoms during TB treatment
- Prompt increase in pyridoxine dosage to 100 mg daily if early signs of neuropathy develop 1, 2
Special Situations
Multidrug-Resistant TB (MDR-TB)
Patients on second-line TB drugs may require continued pyridoxine supplementation, particularly if cycloserine is part of the regimen, as it can also cause neurological side effects 1.
TB-HIV Co-infection
HIV-positive patients are at higher risk for peripheral neuropathy from both HIV infection and isoniazid therapy, making pyridoxine supplementation particularly important in this population 5.
Newer Treatment Regimens
For the 4-month rifapentine-moxifloxacin regimen, pyridoxine (25-50 mg/day) should still be given with isoniazid to all patients 1.
Safety Considerations
- Long-term high-dose supplementation (>500 mg/day) can paradoxically cause sensory neuropathy
- Even doses as low as 100 mg/day have been associated with neurological effects with prolonged use
- The recommended preventive dose (25-50 mg) has an excellent safety profile 2
Cost Considerations
Low-dose pyridoxine (6 mg daily) has been shown to be effective in preventing isoniazid-induced neuropathy in resource-limited settings, making prophylaxis feasible even in developing countries 6.