Synonyms: 2,5-Pyrrolidinedione,1-[[[2',3',6',7',12',13',16',17'-octahydro-3-oxospiro[isobenzofuran-1(3H),9'-[1H,5H,9H,11H,15H]xantheno[2,3,4-ij:5,6,7-i'j']diquinolizin]-5(or6)-yl]carbonyl]oxy]- (9CI); Spiro[isobenzofuran-1(3H),9'-[1H,5H,9H,11H,15H]xantheno[2,3,4-ij:5,6,7-i'j']diquinolizine],2,5-pyrrolidinedione deriv.