A 40-year-old male on anti-TB therapy develops peripheral neuropathy after 3 months of treatment. Which deficiency is responsible?

Correct option is B

Isoniazid causes competitive inhibition of pyridoxal-5-phosphate, leading to Vitamin B6 deficiency. This results in neuropathy, which is prevented by pyridoxine supplementation.
Explanation of options: (a) ✘ Thiamine deficiency causes beriberi, Wernicke’s encephalopathy, not INH neuropathy. (b) ✔ Correct; INH binds pyridoxine → deficiency → neuropathy. (c) ✘ B12 deficiency causes subacute combined degeneration, not directly linked to INH. (d) ✘ Riboflavin deficiency leads to cheilitis/glossitis, not neuropathy.