Diphenylhydantoin and primidone (1:2) Hydantoin, 5,5-diphenyl-, and 5-ethyldihydro-5-phenyl-4,6(1H,5H)-pyrimidinedione (1:2) MU1160000 Phenytoin and primidone (1:2) Primidone and diphenylhydantoin (2:1) Primidone and phenytoin (2:1)