Rosiglitazone is an anti-diabetic drug in the thiazolidinedione class of drugs. It works as an insulin sensitizer, by binding to the PPAR receptors in fat cells and making the cells more responsive to insulin. It is marketed by the pharmaceutical company GlaxoSmithKline (GSK) as a stand-alone drug (Avandia) and in combination with metformin (Avandamet) or with glimepiride (Avandaryl). Annual sales peaked at approx $2.5bn in 2006, but declined after reports of adverse effects. The drug's patent expires in 2012. - Source: Wikipedia