What the largest selling drug in the world?

Pfizer, Incorporated (NYSE: PFE) (pronounced 'faɪzəɹ or 'faɪzə), is the world's largest pharmaceutical company. Pfizer is based in New York City. It produces the number-one selling drug Lipitor (atorvastatin, used to lower blood cholesterol); the oral antifungal medication Diflucan (fluconazole), the long-acting antibiotic Zithromax (azithromycin), the well-known erectile dysfunction drug Viagra (sildenafil citrate), and the anti inflammatory Celebrex (celecoxib) (also known as Celebra outside USA).