This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anaesthesia, Subject name: Pharmacology
[{'content': 'Which of the following is a skeletal muscle relaxant that acts as a central a2 adrenergic agonist: \nSelect and explain. \nA. Tizanidine, B. Brimonidine, C. Chlormezanone, D. Quinine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: * Tizanidine and brimonidine are alpha2 adrenergic agonists. Tizanidine is used as a centrally acting muscle relaxant whereas brimonidine is used topically for the treatment of glaucoma. * Chlormezanone is a centrally acting muscle relaxant that acts by inhibiting the spinal internuncial neurons. * Quinine is a directly acting peripheral muscle relaxant.', 'role': 'assistant'}]