A 46-year-old woman starting anti-tubercular therapy asks why she was prescribed an extra tablet alongside her four-drug regimen. The supplement protects against a dose-dependent sensorimotor peripheral neuropathy caused by interference with pyridoxine metabolism. Which drug makes this supplement necessary?
- A Pyrazinamide
- B Rifampicin
- C Isoniazid ✓
- D Ethambutol
Correct answer: C. Isoniazid
Explanation
Isoniazid promotes renal excretion of pyridoxine and forms inactive complexes with it, producing a glove-and-stocking neuropathy whose risk rises in pregnancy, alcoholism, malnutrition, diabetes, and HIV infection, hence routine pyridoxine co-prescription. Ethambutol causes retrobulbar optic neuritis with impaired red-green color vision, pyrazinamide causes hyperuricemia and hepatitis, and rifampicin is associated with orange discoloration of secretions and enzyme induction rather than neuropathy.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.