2,7-Difluorospiro(9H-fluorene-9,4'-imidazolidine)-2',5'-dione 2,7-Difluorospiro(fluorene-9,4'-imidazolidine)-2',5'-dione 89391-50-4 AL 1576 Alcon 1576 HOE 843 Imirestat Imirestat [INN] Imirestatum [INN-Latin] Spiro(9H-fluorene-9,4'-imidazolidine)-2',5'-dione, 2,7-difluoro-