Abstract

Several compounds of medical or physiological interest were screened for direct antithyroid activity, by employing the thyroid slice-I131 technique. The following were found to be relatively strongly antithyroid at the indicated concentration (in mgm. per ml. of incubation medium). Reserpine (0.083), chlorpromazine (0.36), tetraethylammonium chloride (6.7), Regitine (0.33), Thiopental sodium (0.26, 0.026), colchicine (0.33), phenylbutazone (0.33, 0.033), Geigy G-25671 (0.33), Actrope (6.7). The predominant feature of the direct antithyroid action of all these agents, except chlorpromazine, was inhibition of the organic binding of I131 by the thyroid.