The invention provides solid forms of lesinurad with an amino group-containing organic base of formula R1-NH-R2,wherein the R1 and R2 groups are independently selected from the group consisting of -C(=O)-NH2, hydrogen, a linear or branched C1-C6 alkyl or C1-C6 cycloalkyl while the alkyl or cycloalkyl are optionally substituted by at least one hydroxy group,provided that at least one of the R1 and R2 groups is not hydrogen.Further, an amorphous and crystalline form of lesinurad free acid are disclosed.Methods of production and medical uses of the solid forms of lesinurad are also provided by the present invention.
