Iopanoic acid and ipodate salts have been used for oral cholangiography to visualize the biliary ducts. Ipodate salts have been used for the long-term treatment of Graves' disease and in hyperthyroidism. Ipodate reduced levels of T3 and T4 in the patients. Ipodate also inhibits the conversion of T4 to T3. It is not considered a first-line approach. Ipodate sodium lacks FDA approval for these uses. During investigation of mechanism of action was discovered, that binding of sodium ipodate with nuclear T3 receptors was not a prominent mechanism via which the drug attenuates T3 effects in vivo. Sodium ipodate could enhance T3 effects at the cellular level and that enhancement could not be reflected by routinely monitored serum TSH.

Iopydol is an X-ray contrast medium used in conjunction with iopydone as the proprietary preparation, Hytrast, for the bronchography.

BUNAMIODYL is an cholecystographic agent which was used to aid the radiographic visualization of the gallbladder for detecting the presence of gallstones in cholelithiasis patients. It was withdrawn from the market due to nephropathy.

Iodipamide is used as a contrast agent for cholecystography and intravenous cholangiography. Following intravenous administration of Cholografin Meglumine, iodipamide is carried to the liver where it is rapidly secreted. The contrast medium appears in the bile within 10 to 15 minutes after injection, thus permitting visualization of the hepatic and common bile ducts, even in cholecystectomized patients. Iodipamide (Cholografin Meglumine) is indicated for intravenous cholangiography and cholecystography as follows: (a) visualization of the gallbladder and biliary ducts in the differential diagnosis of acute abdominal conditions, (b) visualization of the biliary ducts, especially in patients with symptoms after cholecystectomy, and (c) visualization of the gallbladder in patients unable to take oral contrast media or to absorb contrast media from the gastrointestinal tract. The biliary ducts are readily visualized within about 25 minutes after administration, except in patients with impaired liver function. The gallbladder begins to fill within an hour after injection; maximum filling is reached after two to two and one-half hours. Organic iodine compounds block x-rays as they pass through the body, thereby allowing body structures containing iodine to be delineated in contrast to those structures that do not contain iodine. The degree of opacity produced by these iodinated organic compounds is directly proportional to the total amount (concentration and volume) of the iodinated contrast agent in the path of the x-rays. Iodipamide's primary excretion through the hepato-biliary system and concentration in bile allows visualization of the gallbladder and biliary ducts.

Iotroxic acid (INN), also known as meglumine iotroxate (BAN) (Biliscopin) for infusion is indicated for radiological examination of the hepatic and biliary ducts and gallbladder when examination by oral technique is unsuccessful or inappropriate. Following intravenous administration Biliscopin is rapidly excreted, mainly by the liver into the bile. Visualisation of the hepatic and common bile ducts and the gallbladder can, therefore, be achieved. Visualisation of the biliary ducts is usually possible 30-60 minutes after completion of administration. In vitro meglumine iotroxate binds to plasma proteins to the extent of 60-90% depending on concentration. In animals it crosses the placental barrier. This agent is the single intravenous cholangiographic agent, which is currently available in Australia.

Iodine-labeled ioglycamic acid (Bilivistan or Biligram) has been used as a contrast medium for intravenous cholangiocystography.

Ioxitalamic acid is a contrast media, which was used as a meglumine salt under the name Telebrix for intravenous urography; computed tomography; digital angiography; angiocardiography (ventriculography, coronary angiography). The drug is no longer available on the market.

Ioglicinate, contrast agent, is used in computed tomography.

Iodoalphionic acid is the contrast medium, which was used for gallbladder examination. It is rarely appeared in the colon and, therefore, rarely masked the gallbladder. The density of the shadow produced by Iodoalphionic acid was greater than that produced by iodophthalein. It was reliable peroral cholecystographic medium, which was less objectionable to take and seldom causes vomiting. Diarrhoea occurred in some cases, but not more often than with tetraiodophenolphthalein. The ingestion of Iodoalphionic acid resulted in low thyroidal radioiodine accumulation for periods ranging from a few weeks to many months.

Iobenguane, mainly use as a radiopharmaceutical, used in a scintigraphy method called MIBG scan. Synthetic guanethidine derivative that locates phaeochromocytomas and neuroblastomas. The radioisotope used can either be iodine-123 for imaging or iodine-131 for destruction of tissues that metabolize noradrenaline. Iodine 123 is a cyclotron-produced radionuclide that decays to Te 123 by electron capture. Images are produced by a I123 MIBG scintigraphy. It localizes to adrenergic tissue and thus can be used to identify the location of tumors such as pheochromocytomas and neuroblastomas. With I-131 it can also be used to eradicate tumor cells that take up and metabolize norepinephrine. The radioactive iodine component is responsible for its imaging properties. Iobenguane and guanethidine are substrates for the norepinephrine transporter (NET) and accumulate by the uptake mechanism into presynaptic nerve endings. Unlike norepinephrine, these drugs are protonated under physiologic conditions; therefore, they do not cross the blood–brain barrier and in vivo uptake is limited primarily to systemic neuronal tissue. The accumulation of iobenguane in myocardial tissue is also dictated by the high fraction of aortic blood flow that enters the coronary arteries. This physiology constitutes an ideal molecular targeting mechanism for diagnosis of various cardiac diseases, including heart failure, heart transplant rejection, ischemic heart disease, dysautonomia, and drug-induced cardiotoxicity, as well as cardiac neuropathy related to diabetes mellitus and Parkinson disease