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: Pharmacology
[{'content': 'Finasteride is a: \nSelect and explain. \nA. 5 alpha reductase inhibitor, B. PDE inhibitor, C. Alpha la blocker, D. Androgen receptor blocker', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Finasteride is a competitive inhibitor of the enzyme 5-alpha reductase which is responsible for the conversion of testosterone into a more active dihydrotestosterone responsible for the androgen action. When used in benign prostatic hyperophy, it reduces the prostate size and increased peak urinary flow rate. It is also used in male pattern baldness and as a palliative treatment in prostatic carcinoma. Ref: K D Tripathi Textbook of Pharmacology, 5th Edition, Page 272', 'role': 'assistant'}]