A patient with moderate-to-severe plaque psoriasis is started on apremilast. Which enzyme does this drug selectively inhibit?
- A Phosphodiesterase 4 ✓
- B Dihydrofolate reductase
- C Calcineurin
- D Xanthine oxidase
Correct answer: A. Phosphodiesterase 4
Explanation
Apremilast is an oral selective phosphodiesterase 4 (PDE4) inhibitor that increases intracellular cAMP, thereby downregulating pro-inflammatory cytokines like TNF-alpha and IL-23. Dihydrofolate reductase is the enzyme inhibited by methotrexate. Calcineurin is the target of cyclosporine. Xanthine oxidase is the enzyme inhibited by allopurinol. This makes phosphodiesterase 4 the correct answer.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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