This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Opioids, Subject name: Pharmacology
Which of the following is TRUE for morphine : 
Select and explain. 
A. Tolerance to all its actions except sedation and euphoria, B. Tolerance to all side effects except constipation and miosis., C. It is a peripherally acting analgesic., D. It has no abuse potential.
B: Tolerance to all side effects except constipation and miosis.
Answer: B: Tolerance to all side effects except constipation and miosis. 
Explanation: Ans. is 'b' Tolerance to all its action except constipation and miosis Tolerance is exhibited to most actions of morphine except for miosis and constipation. Morphine is a centrally acting analgesic. It has site-specific depressant and stimulant action in CNS. Morphine produces pronounce psychological and physical dependence, its abuse liability is very high. Withdrawal of morphine is associated with marked drug seeking behaviour. These are: Lacrimation* Mydriasis * Sweating Diarrhoea* Insomnia* Tremor Rise in B.P.