A PDE 4 inhibitor. **Explanation:** **Apremilast** is an oral small-molecule inhibitor of **Phosphodiesterase 4 (PDE4)**. In inflammatory cells, PDE4 is the dominant enzyme responsible for the degradation of cyclic adenosine monophosphate (cAMP). By inhibiting PDE4, Apremilast increases intracellular cAMP levels, which in turn downregulates the inflammatory response by modulating the expression of pro-inflammatory cytokines (like TNF-α, IL-23, and IFN-γ) and increasing anti-inflammatory cytokines (like IL-10). **Analysis of Options:** * **Option B (Correct):** Apremilast specifically targets PDE4. It is FDA-approved for the treatment of **moderate-to-severe plaque psoriasis** and **psoriatic arthritis**. * **Option A:** PDE3 inhibitors (e.g., **Milrinone**, Amrinone) are primarily used as inotropes in acute heart failure to increase cardiac contractility and cause vasodilation. * **Option C:** PDE5 inhibitors (e.g., **Sildenafil**, Tadalafil) are used for erectile dysfunction and pulmonary arterial hypertension by increasing cGMP levels. * **Option D:** PDE6 is found in the retina. Inhibition of PDE6 (often a side effect of PDE5 inhibitors) leads to visual disturbances, such as the "blue-tint" vision (cyanopsia). **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Administered **orally**, making it a preferred alternative to biologicals for patients who prefer to avoid injections. * **Side Effects:** The most common side effects are **diarrhea, nausea**, and upper respiratory tract infections. A significant psychiatric side effect to remember is **depression and weight loss**. * **Indications:** Plaque psoriasis, Psoriatic arthritis, and **Behçet’s disease** (for oral ulcers). * **Mechanism Mnemonic:** Apremilast = **4**premilast (PDE**4**).

Drugs Used in Skin Disorders — MCQs

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Drugs Used in Skin Disorders — MCQs

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Sunscreens and Photoprotective Agents

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