<prompt> Anti TB drug causing optic neuritis:IsoniazidRifampicinPyrazinamideEthambutol  <response>: Ref: KDT 6th ed. pg. 742 Side effect of Ethambutol: Loss of visual acuitycolour vision, field defects due to optic neuritis is the most important dose and duration of therapy dependent toxicity. Important side effects of antitubercular drugs: Peripheral neuropathy due to vit B6 deficiency: ISONIAZID Orange color urine-RIFAMPICIN Flu-like symptoms- RIFAMPICIN Hyperuricemiagout- PYRAZINAMIDE Optic neuritis- ETHAMBUTOL Nephrotoxic, Ototoxic, Neuromuscular Junction Blocker- STREPTOMYCINOther important points to remember about Anti TB drugs: First line anti TB drugs are: HRZE Isoniazid, Rifampicin, Pyrazinamide, Ethambutol All first line drugs are bactericidal EXCEPT- Ethambutol it is bacteriostatic Most hepatotoxic ATT-Pyrazinamide 1st line ATT with exclusive intracellular action-Pyrazinamide 1st line ATT with exclusive extracellular action-Streptomycin Which anti TB drugs are NOT hepatotoxic-Ethambutol and Streptomycin. It should not be used in children below 6 years of age because these young patients may not be able to report visual impairment. 