Which RIPE drug is most associated with optic neuritis and has relatively low hepatotoxic risk?

• A. Ethambutol.
• B. Isoniazid.
• C. Rifampin.
• D. Pyrazinamide.

Answer: (A)

Ethambutol is known for its effect on the optic nerve, causing optic neuritis with symptoms like decreased visual acuity and color vision changes (especially red-green). This drug’s toxicity on the optic apparatus is a classic, dose-related concern, so monitoring vision is important during therapy. At the same time, ethambutol carries relatively low risk of liver injury compared with the other RIPE components, which makes it stand out when the question asks for both optic neuritis association and low hepatotoxic risk. In contrast, isoniazid and pyrazinamide are more strongly linked to hepatotoxicity, and rifampin, while hepatotoxic as well, is not typically associated with optic neuritis. So ethambutol best fits both parts of the question. If optic neuritis occurs, stopping ethambutol and reassessing treatment is the typical course, and baseline and periodic eye exams help catch early changes.