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: Unknown
Drug used for post-operative shivering - 
Select and explain. 
A. Atropine, B. Pethidine, C. Thiopenone, D. Suxamethonium
B: Pethidine
Answer: B: Pethidine 
Explanation: Ans. is 'b' i.e., Pethidine Post-anaesthesia shivering (PAS)o Post anaesthesia (post operative) shivering occurs in 40% of patients recovering from general anaesthesia,o Some time it is preceded by central hypothermia and peripheral vasoconstriction, indicating that it is a thermoregulatory mechanism.o Pethidine is most effective drug for treatment of PAS.o Other drugs used are -clonidine, doxapram, ketanserin, alfentonil, butorphanol, chlorpromazine.