Abstract Two new 125 I-labeled barbituric acid analogs, 5-ethyl-5-(E-1-iodo-1-penten-5-yl) 2- thiobarbituric acid (4) and 5-ethyl-5-(m-iodophenyl) barbituric acid (7), have been prepared and evaluated in rats as potential cerebral perfusion agents. Annulation of 2-ethyl-2-(E-1-
