Metformin lactic acidosis, acute renal failure and rofecoxib

A patient with acute renal failure associated with lactic acidosis as a result of concurrent treatment with metformin is described. Rofecoxib may have been a precipitating factor. The risk of renal failure with the use of traditional NSAIDs is well known. However, what is less well appreciated is the role that the COX 2 inhibitors may play in the development of renal failure which, when it occurs in a patient on metformin, can lead to a potentially disastrous outcome.