Fused heterocyclic ring systems in which a quinoline or a pyridine component is "fused" to a pyrimidine having a 2-methyl, 2-ethyl, or 2-acetyl group and a 4-keto group, and to similar ring systems in which a quinoline, a naphthalene or a pyridine component is fused to a pyrimidine having a 2-carboxy group and a 4-keto group, derivatives, and pharmaceutically-acceptable cationic salts thereof, and their use as antiallergy agents, and intermediates therefor.