This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
Respiratory centre depression can be caused by all except 
Select and explain. 
A. Opium, B. Strychnine, C. Barbiturates, D. Gelsemium
B: Strychnine
Answer: B: Strychnine 
Explanation: Opium causes significant respiratory depression. Barbiturates does not produce respiratory depression. Strychnine doesn't produce respiratory depression , it is a convulsant. Ref: KD Tripathi 8th ed.