Pirfenex 200mg tablet belongs to the medication class known as transforming growth factor inhibitors. It contains an active ingredient called Pirfenidone. It is used to treat idiopathic pulmonary fibrosis (IPF). Idiopathic pulmonary fibrosis is a type of lung disorder in which tissues of the lungs become scarred and inflamed, resulting in breathing difficulties. This medicine should not be used if you have severe liver disorders or kidney disorders, if you are taking fluvoxamine (which treats depression and obsessive-compulsive disorder), or if you are allergic to any of the ingredients of this medicine. Do not drink grapefruit juice while taking this medicine.