Tranilast is an anti-allergic drug inhibiting the release of substances such as histamine and prostaglandins from mast cells, which suppresses collagen synthesis of fibroblasts derived from keloid tissues. Tranilast (3-300 mM) suppresses the collagen synthesis of fibroblasts from keloid and hypertrophic scar tissue but not healthy skin fibroblasts. Tranilast (30-300 mM) inhibits the release of transforming growth factor (TGF)-beta 1 from keloid fibroblasts, which enhances the collagen synthesis of keloid fibroblasts. ^[1] Tranilast improves keloids and hypertrophic scars which originate from the abnormal proliferation and excessive collagen accumulation of fibroblasts. Tranilast inhibits the release of TGF-beta 1, IL-1 beta and PGE2 from the human monocytes-macrophages. ^[2] Tranilast inhibits the proliferation stimulated with fetal bovine serum (FBS), TGF-beta 1 and platelet-derived growth factor-BB (PDGF-BB) as well as PDGF-BB-induced migration. Tranilast exhibits inhibitory effects on spontaneous collagen synthesis and TGF-beta 1-induced collagen and glycosaminoglycan synthesis. ^[