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: Anaesthesia
Which of the following anesthetic agent lacks analgesic effect: March 2013 
Select and explain. 
A. N20, B. Thiopentone, C. Ketamine, D. Fentanyl
B: Thiopentone
Answer: B: Thiopentone 
Explanation: Ans. B i.e. Thiopentone Thiopentone Ultra sho acting barbiturate (because of rapid redistribution), Lacks analgesic effect, First sign on intra-aerial injection: - White hands I/V injection presents as: - Pain, - Hypotension etc. C/I in: Porphyria (may precipitate porphyria)