Carbazole derivatives and their use as 5HT-induced antagonists

The invention relates to compounds of the general formula (I): (I) wherein R1 represents a group CO2R5, COR5, CONR5R6 or SO2R5 (wherein R5 and R6, which may be the same or different, each represents a hydrogen atom, a C1-6 alkyl or C3-7 cycloalkyl group, or a phenyl or phenyl-(C1-4)alkyl group in which the phenyl group is optionally substituted by one or more C1-4 alkyl, C1-4 alkoxy or hydroxy groups or halogen atoms, with the proviso that R5 does not represent a hydrogen atom when R1 represents a group CO2R5 or SO2R5); and one of the groups represented by R2, R3 and R4 is a hydrogen atom or a C1-6 alkyl, C3-7 cycloalkyl, C2-6 alkenyl or phenyl-(C1-3)alkyl group and each of the other two groups, which may be the same or different, represents a hydrogen atom or a C1-6 alkyl group; and physiologically acceptable salts and solvates thereof. The compounds are potent and selective antagonists of "neuronal" 5-hydroxytryptamine receptors and are useful in the treatment of psychotic disorders (e.g. schizophrenia and mania); anxiety; pain; gastric stasis; symptoms of gastrointestinal dysfunction such as occur with dyspepsia, peptic ulcer, reflux oesophagitis and flatulence; migraine; and nausea and vomiting.