PHENOTHIAZINES,LEUR PROCEDE DE PREPARATION ET PRODUITS EN CONTENANT

Compounds of the formula (I): or salts, esters or amides, thereof, wherein R1 is a C1-7 bivalent 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, C1-4 alkoxy, C1-4 alkyl optionally substituted by one to three halogen atoms; or a group R1 CO2H as hereinbefore defined and A is C1-4 alkylene or ANR2R3 forms a group anti-allergic and anti-histaminic activity. Processes for preparing these compounds, novel intermediates in their preparation, pharmaceutical compositions containing the compounds, and the compounds for use in medicine are also described.