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
[{'content': 'Which of the following local anaesthetic is the shoest acting which aids in obstetric anaesthesia? \nSelect and explain. \nA. Tetracaine, B. Bupivacaine, C. Prilocaine, D. Chloroprocaine', 'role': 'user'}, {'content': "Answer: D \nExplanation: Chloroprocaine is a chlorinated derivative of procaine. Its major assets are its rapid onset and sho duration of action and its reduced acute toxicity due to its rapid metabolism (plasma t1/2 ~25 seconds). Chloroprocaine gained widespread use as an epidural agent in obstetric anesthesia, where its rapid hydrolysis served to minimize risk of systemic toxicity or fetal exposure. Ref: Catterall W.A., Mackie K. (2011). Chapter 20. Local Anesthetics. In B.C. Knollmann (Ed), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.", 'role': 'assistant'}]