From the Guidelines
Vitamin B6 (pyridoxine) should be given with isoniazid to prevent peripheral neuropathy, a common side effect of isoniazid therapy, with a recommended dose of 25-50 mg of pyridoxine daily while taking isoniazid, as stated in the official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America clinical practice guidelines 1. This supplementation is particularly important for patients at higher risk of developing neuropathy, including:
- Pregnant women
- Breastfeeding mothers
- Malnourished individuals
- Alcoholics
- Diabetics
- HIV-positive patients
- The elderly
- Those with kidney disease Isoniazid causes neuropathy by interfering with pyridoxine metabolism, specifically by inhibiting the conversion of pyridoxine to its active form (pyridoxal phosphate), which is essential for nerve function. Without adequate pyridoxine, patients may experience tingling, numbness, and pain in their extremities. For most patients on standard isoniazid therapy for tuberculosis treatment or prophylaxis, routine B6 supplementation is recommended throughout the entire course of isoniazid treatment, which typically ranges from 6-9 months, as also supported by the executive summary of the official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America clinical practice guidelines 1.
From the FDA Drug Label
Pyridoxine (vitamin B6) deficiency is sometimes observed in adults with high doses of isoniazid and is considered probably due to its competition with pyridoxal phosphate for the enzyme apotryptophanase. Vitamin B6 (Pyridoxine) is given with Isoniazid to prevent or treat Pyridoxine deficiency, which can occur due to the competition between Isoniazid and Pyridoxal phosphate for the enzyme apotryptophanase 2, 2.
- This is particularly important in cases of high-dose Isoniazid therapy or Isoniazid overdosage, where Pyridoxine deficiency can lead to neurotoxicity.
- The administration of Pyridoxine can help prevent or mitigate this adverse effect.
From the Research
Isoniazid and Vitamin B6 Supplementation
- Isoniazid is a medication used to treat tuberculosis, but it can cause peripheral neuropathy as a side effect 3, 4, 5, 6.
- Vitamin B6 (pyridoxine) supplementation is often given with isoniazid to prevent the development of peripheral neuropathy 4, 5, 6.
- The mechanism of isoniazid-induced neuropathy is thought to be related to the inhibition of pyridoxine's metabolic functions, which can be prevented by supplementing with vitamin B6 4.
Prevention and Treatment of Isoniazid-Induced Neuropathy
- Studies have shown that vitamin B6 supplementation can prevent the development of peripheral neuropathy in patients taking isoniazid 4, 5, 6.
- In cases where neuropathy has already developed, vitamin B6 supplementation can help improve symptoms and prevent further progression 5, 6.
- The dosage of vitamin B6 supplementation varies, but it is often given at a dose of 6 mg daily 5.
Importance of Vitamin B6 Supplementation
- Vitamin B6 supplementation is particularly important in patients who are at high risk of developing peripheral neuropathy, such as those with malnutrition or slow acetylator status 3, 4, 6.
- Timely therapeutic intervention with high-dose vitamin B6 can reduce the long-term morbidity associated with isoniazid-induced neuropathy 6.
- However, it is also important to note that high levels of vitamin B6 can be neurotoxic, and supplementation should be given at permitted daily doses 7.