| abstract |
Compounds of the formula (I): <CHEM> or salts, esters or amides thereof; wherein R1 is a C1-7 bivalent aliphatic hydrocarbon group or a single bond; R2 and R3 are the same or different and are each hydrogen, C1-4 alkyl or taken together with the nitrogen comprise a nitrogen-containing heterocyclic ring having four to six ring members; R4 is hydrogen, halogen, hydroxy, cyano, C1-4 acyloxy, C1-4 alkoxy or C1-4 alkyl optionally substituted by one to three halogen atoms, X is -N= or -CH=; and A and B each represents hydrogen atoms or -CA-CB= represents -C=C- are useful in the symptomatic treatment of allergic conditions. Processes for preparing the compounds, intermediates useful in their preparation, pharmaceutical compositions containing them and their use in the symptomatic treatment of allergic conditions are also described. |