This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Orange coloured urine is due to: 
Select and explain. 
A. Rifampicin, B. INH, C. Pyrazinamide, D. Ethambutol
A: Rifampicin
Answer: A: Rifampicin 
Explanation: The urine and the secretions of the patients receiving Rifampicin becomes orange-red and it is harmless. Such a side effect is not encountered with the other three anti-tubercular drugs mentioned as choices. Ref: K D Tripathi Textbook of Pharmacology, 5th Edition, Pages 698-701