Abstract: Compounds of the formula: ##STR1## wherein R represents the group --CH.sub.2 CH.sub.2 OH or --CH.sub.2 CHOHCH.sub.2 OH, particularly in racemic or optically active form, are employed as active ingredients in X-ray contrast agents for intracerebral, but particularly for vascular use. The compounds are prepared by reacting 5-(N-acetamido)-2,4,6-triiodo-N,N'-bis-(2,3-dihydroxypropyl)isophthalamide or an O-acetyl derivative thereof with an appropriate hydroxyalkylating agent and subsequently, if necessary, hydrolysing any unwanted O-acetyl groups.

Abstract: This invention relates to novel X-ray contrast agents particularly for use in the cerebrospinal cavities, comprising non-ionic alkanols carrying at least one N-bonded secondary or tertiary amide group and having at least two hydroxyl groups and at least one iodine atom in the molecule. Particularly useful compounds include the N-hydroxyalkyl iodoalkane sulphonamides having at least two hydroxyl groups, tri- and tetra-iodobenzene carrying carbamoyl, acylamino and/or acylaminomethyl substituents and having at least two hydroxyl groups in the molecule and at least one N-hydroxyalkyl group. Particularly preferred compounds comprise 2,4,6-triiodobenzamides which may be 3- and/or 5-substituted with a variety of groups. The compounds all show markedly low toxicities and a number show very high levels of water solubility.