Compositions of alkylbenzenes for visualization of the gastrointestinal tract using X-ray contrast

A method of carrying out x-ray examination of the gastrointestinal tract of a patient in need of such examination which comprises orally or rectally administering to the patient an x-ray contrast composition comprising an x-ray contrast agent, or a pharmaceutically acceptable salt thereof, having the formula;

• ##STR16## wherein R is methyl, ethyl, n-propyl, C.sub.4 -C.sub.25 alkyl, cycloalkyl, unsaturated allyl or halo-lower-alkyl, each of which may be optionally substituted with halo, fluoro-lower-alkyl, aryl, lower-alkoxy, hydroxy, carboxy or lower-alkoxy carbonyl (CR.sub.1 R.sub.2).sub.p --(CR.sub.3 .dbd.CR.sub.4).sub.m Q, or (CR.sub.1 R.sub.2).sub.p --C.tbd.C--Q;
• R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently H, lower-alkyl optionally]substituted with halo;
• n is 2-5;
• m is 2-5;
• p is 1-10;
• and
• Q is H, lower-alkyl, lower-alkenyl, lower-alkynyl, lower-alkylene, aryl, or aryl-lower alkyl
• in an aqueous, pharmaceutically acceptable carrier, said pharmaceutically acceptable carrier containing at least one surfactant selected from the group consisting of a zwitterionic surfactant, trimethylammonium bromide, sodium lauryl sulfate, sodium heptadecyl sulphate, alkyl benzenesulphonic acid, sodium butylnaphthalene sulfonate, sulphosuccinate, carboxylic esters, carboxylic amides, ethoxylated alkylphenols and ethoxylated aliphatic alcohols, sorbitan esters, polyoxyethylene alkyl ethers and polyoxyethylene sorbitan fatty acid esters;
• and performing an x-ray examination of the patient.