This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunomodulator, Subject name: Pharmacology
[{'content': 'Which of the following is dihydroorotate dehydrogenase inhibitor? \nSelect and explain. \nA. Methotrexate, B. Leflunomide, C. Hydroxychloroquine, D. Sulfasalazine', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Leflunomide Important DMARDsMechanism of action* MethotrexateDihydrofolate reductase inhibitor* SulfasalazineSulfapyridine moiety suppresses the generation of superoxide radicals and cytokine production* LeflunomideIs rapidly converted in the body to an active metabolite which inhibits dihydroorotate dehydrogenase.* Hydroxychloroquine* Reduce monocyte IL-1, consequently inhibiting B-cells* Interferes with antigen processing* Stabilizes lysosome and free radical scavenging.", 'role': 'assistant'}]