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
Which drug has more analgesic effects than morphine? 
Select and explain. 
A. Heroin, B. Apomorphine, C. Codeine, D. Pethidine
A: Heroin
Answer: A: Heroin 
Explanation: Codeine is less potent than morphine as an analgesic(60mg codeine=10 mg morphine). 100 mg pethidine= 10 mg morphine.Heroin is conveed to morphine in the body and has higher lipid solubility than morphine. Ref KD Tripathi 8th ed.