The invention relates to a pharmaceutical composition for rectal administration which comprises 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)-methyl]-4H-carbazol-4-one in the form of its free base or a pharmaceutically acceptable solvate thereof as active ingredient, together with one or more pharmaceutically acceptable carriers or excipients. Methods for the manufacture of such compositions and for their use in the treatment of conditions mediated through the action of 5-hydroxytryptamine at 5-HT3 receptors are also described.