FCPS part 1 Medicine solved mcqs with explanation Q2

FCPS part 1 Medicine solved mcqs with explanation

Q2: A patient has been taking anti-tuberculous therapy for MDR-TB. His drugs regimen contains 6 drugs. The patient eventually develops difficulty in distinguishing red & green colours. Which of the following drugs is responsible for this effect?

a) Amiodrone

b) Pyrazinamide

c) Rifampicin

d) Ethambutol

e) Ciprofloxacin

Correct Answer: d

Explanation:

Ethambutol is one of the drugs used in anti-tuberculous therapy. Optic neuritis is an important, though rare side effect of ethambutol. If optic neuritis develops, red-green colour vision may be lost first. This agent should probably not be used in young children in whom it may be difficult to assess vision.