iopanoic acid iopanoic acid iopanoic acid is an iodine-containing radiocontrast medium used in cholecystography. both iopanoic acid and ipodate sodium are potent inhibitors of thyroid hormone release from thyroid gland, as well as of peripheral conversion of thyroxine (t4) to triiodothyronine (t3). these compounds inhibit 5'deiodinase (5'did-1 and 5'did-2) enzymes, which catalyse t4-t3 conversion in the thyroid cell, liver, kidney, skeletal muscle, heart, brain, pituitary. this accounts for the dramatic improvement in both subjective and objective symptoms of hyperthyroidism, particularly when they are used as an adjunctive therapy with thioamides (propylthiouracil, carbimazole). they can be used in the treatment of patients with severe thyrotoxicosis (thyroid storm) and significant morbidity (e.g., myocardial infarction, or stroke) for rapid control of elevated plasma triiodothyronine concentrations. the use of iopanoic acid for treatment of thyrotoxicosis has been discontinued in the united states. iopanoic acidclinical dataahfs/drugs.commicromedex detailed consumer informationatc codev08ac06 (who) identifiers iupac name (rs)-2-butanoic acid cas number96-83-3pubchem cid3735drugbankdb08946 nchemspider3604uniife9794p71jkeggd01014chemblchembl867 ycomptox dashboard (epa)dtxsid6023159 echa infocard100.002.310 chemical and physical dataformulac11h12i3no2molar mass570.935 g·mol−13d model (jsmol)interactive imagemelting point162–163 °c (324–325 °f) smiles ccc(cc1=c(c(=c(c=c1i)i)n)i)c(=o)o inchi inchi=1s/c11h12i3no2/c1-2-5(11(16)17)3-6-7(12)4-8(13)10(15)9(6)14/h4-5h,2-3,15h2,1h3,(h,16,17)key:oirfjrbsrorbcm-uhfffaoysa-n in addition to inhibiting deiodinase enzymes, iopanoic acid is also a substrate of type 1 deiodinase. iopanoic acid underwent monodeiodination in the presence of type 1 deiodinase in a microsomal mouse liver preparation.