Felbinac (INN, or biphenylylacetic acid) is a topical medicine, belonging to the family of medicines known as nonsteroidal anti-inflammatory drugs (NSAIDs) of the arylacetic acid (not arylpropionic acid) class, which is used to treat muscle inflammation and arthritis. It is an active metabolite of fenbufen. Felbinac (INN, or biphenylylacetic acid) is a topical medicine, belonging to the family of medicines known as nonsteroidal anti-inflammatory drugs (NSAIDs) of the arylacetic acid (not arylpropionic acid) class, which is used to treat muscle inflammation and arthritis. It is an active metabolite of fenbufen.