A monocarboxylic acid that is propionic acid in which one of the hydrogens at position 2 is substituted by a 4-(1-oxo-1,3-dihydroisoindol-2-yl)phenyl group. Initially used as an anti-inflammatory and analgesic, it was withdrawn from the market due to causing severe gastrointestinal bleeding. It has been subsequently found to increase production of the survival motor neuron protein.