Diazabicyclo derivatives as 5-HT3 antagonists

Diazabicyclo derivatives of formula (I) and pharmaceutically acceptable salts thereof: wherein R is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, alkoxyalkyl, oxoalkyl, alkoxycarbonylalkyl, alkoxycarbonyl, acyl, dialkylaminoalkyl, hydroxyalkyl, haloalkyl, cyanoalkyl, heterocycloalkyl, aryl, heteroarylalkyl or arylalkyl, the aryl group and the aryl moiety being optionally substituted by alkoxy, nitro, alkyl, amino or halo; R is hydrogen or alkyl; R and R may be the same or different and each is hydrogen, alkyl, alkenyl, acyl, alkoxyalkyl or arylalkyl wherein the aryl moiety is optionally substituted by alkoxy, nitro, alkyl, amino or halo; with the proviso that when R is hydrogen and both R and R are methyl, R does not represent hydrogen, alkyl, unsubstituted benzyl or dimethylaminoethyl; having 5-HT3 receptor antagonist activity.