PROBLEM TO BE SOLVED: To provide a compound for PDE inhibition and TNF-&alpha； level reduction for the treatment of psoriasis, plaque-type psoriasis, psoriatic arthritis, Behcet's disease, among others.SOLUTION: The invention relates to a novel substituted isoindoline-1,3-dione derivative that is represented by formula I and is an analog of apremilast, where H is replaced by D, and relates to a composition comprising the compound and a carrier.【課題】乾癬、プラーク型乾癬、乾癬性関節炎、ベーチェット病等の治療のためのＰＤＥ阻害及びＴＮＦ－αレベルの低下をまねく化合物の提供。【解決手段】アプレミラストの類似体である式（Ｉ）で表される新規置換イソインドリン-1,3-ジオン特定のＨがＤに置換された誘導体、前記化合物と担体とを含む組成物。【選択図】なし
