Propyliodone (INN, trade name Dionosil) is a molecule used as a contrast medium. It was developed by a team at Imperial Chemical Industries in the late 1930s. Propyliodone used as radiopque medium for brochographic use. When directly instilled into the bronchi resulting in well-defined bronchograms for atleast 30 min. Because of its toxicity, Propyliodone should only be used if absolutely essential. It is of Synthetic origin and belongs to Iodinated Radio-opaque Compounds. It belongs to Radiopaque Agents pharmacological group on the basis of mechanism of action and also classified in Diagnostic Aids pharmacological group. Oral absorption of Propyliodone is found to be 101% and metabolism is reported Lungs and Gut wall. Propyliodone is primarily indicated in conditions like Paget's disease of bone, Radiological contrast agent. Propyliodone produces potentially life-threatening effects which include Fever, Anaphylaxis, Repiratory obstruction, Cerebral embolization, which are responsible for the discontinuation of Propyliodone therapy. The signs and symptoms that are produced after the acute overdosage of Propyliodone include Airway obstruction. The symptomatic adverse reactions produced by Propyliodone are more or less tolerable and if they become severe, they can be treated symptomatically, these include Headache, Fever, Malaise, Nausea and vomiting, Aching joints.

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.

Acetrizoic acid (trade names Gastrografina, Urografina in Portugal) is a palatable lemon-flavored water-soluble iodinated radiopaque X-ray contrast medium for oral or rectal administration only. Acetrizoic acid is indicated for radiographic examination of segments of the gastrointestinal tract (esophagus, stomach, proximal small intestine, and colon). The preparation is particularly indicated when a more viscous agent such as barium sulfate, which is not water-soluble, is not feasible or is potentially dangerous. Administration of hypertonic Gastrografin solutions may lead to hypovolemia and hypotension due to fluid loss from the intestine.

Iopentol is a non-ionic X-ray contrast medium. It contains a tri-iodinated benzene ring, which, due to a high atomic density of iodine, causes hight attenuation of X-rays. Iopentol It has been used in various radiologic procedures to aid the radiographic visualization of selected tissues and organs. Iopentol is not commercially available in the United States, but was marketed in Europe under tradename Imagopaque for arteriography, urography, phlebography and computed tomography enhancement, arthrography, endoscopic retrograde cholangiopancreatography, hysterosalpingography, and gastrointestinal studies.

Iobenzamic acid is a contrast medium, which was used for cholecystography under the name Osbil. It is assumed that the drug is no longer marketed.

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.

Iobitridol is a contrast medium used for intravenous urography, cerebral computed tomography, computed tomography of the whole body, digital subtraction angiography, arteriography, angiocardiography, venography, CT scan of the thorax. The drug is marketed under the name Xenetix.