This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous General Anesthesia, Subject name: Anaesthesia
[{'content': 'Which anesthetic agent is contraindicated in porphyria: \nSelect and explain. \nA. Propofol, B. Ketamine, C. Thiopentone, D. Etomidate', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans: (c) ThiopentoneRef: KDT 6th ed./374* Thiopentone is an ultrashort acting thiobarbiturate because of rapid redistribution.* It has poor analgesic property.* I/v injection is very painful. Therefore it is contraindicated unless opioids or N2O has been given.* Contraindicated in porphyria patientsAlso Know*Etomidatei insufficiency.* Drugs safe in patients with porphyria: Propofol', 'role': 'assistant'}]