4-[[5-[(Carboxymethyl)thio]-4-(4-cyclopropyl-1-naphthalenyl)-4H-1,2,4-triazol-3-yl]amino]-4-oxo-butanoic Acid is an impurity of drug Lesinurad (L329700), which is used to synthesize febuxostat which is a non-purine analog inhibitor of xanthine oxidase. Febuxostat is approved by the European Medicines Agency and the US Food and Drug Administration for treating gout.