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| | | | Result : Searchterm 'Nonionic Dimer' found in 1 term [ ] and 7 definitions [ ], (+ 2 Boolean[ ] results
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A nonionic dimer consists of 2 joined nonionic monomers. Nonionic dimers are used as x-ray and CT contrast media.
Nonionic dimers have the lowest osmolarity. These contrast materials contain 6 iodine atoms for every 1 particle in solution (CM ratio=6). Modern CT techniques require fast bolus injections and thus low-viscosity, high-concentration, well-tolerated contrast agents. Nonionic dimers have the highest viscosity, which limits the clinical usefulness. Examples of nonionic dimers are iotrolan (Isovist®) and iodixanol (Visipaque™).
See also Contrast Agents.
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| | | | | | | | (CA) Contrast agents are used to change the imaging characteristics, resulting in additional information about anatomy, morphology or physiology of the human body. Radiocontrast agents (also called photon-based imaging agents) are used to improve the visibility of internal body structures in x-ray and CT procedures. Contrast agents are also used to increase the contrast between different tissues in MRI (magnetic resonance imaging) and ultrasound imaging. The ideal imaging agent provides enhanced contrast with little biological interaction.
First investigations with radiopaque materials are done shortly after the discovery of x-rays. These positive contrast agents attenuate x-rays more than body soft tissues due to their high atomic weight. Iodine and barium have been identified as suitable materials with high radiodensity and are used until today in x-ray and CT contrast agents. Iodine-based contrast agents are water-soluble and the solutions are used nearly anywhere in the body. Iodinated contrast materials are most administered intravenous, but can also be introduced intraarterial, intrathecal, oral, rectal, intravesical, or installed in body cavities. Barium sulfate is only used for opacification of the gastrointestinal tract. Negative contrast agents attenuate x-rays less than body soft tissues, for example gas.
Iodinated contrast media are differentiated in:
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Intravascular iodinated contrast agents are required for a large number of x-ray and CT studies to enhance vessels and organs dependent on the blood supply. Injectable contrast agents are diluted in the bloodstream and rapidly distributed throughout the extracellular fluid. The main route of excretion is through the kidneys, related to the poor binding of the agent to serum albumin. The liver (gall bladder) and small intestine provide alternate routes of elimination particularly in patients with severe renal impairment. The use of special biliary contrast agents is suitable for gallbladder CT and cholecystograms because they are concentrated by the liver to be detectable in the hepatic bile.
The introduction of fast multi-detector row CT technology, has led to the development of optimized contrast injection techniques. The amount of contrast enhancement depends on the contrast agent characteristics, such as iodine concentration, osmolality, viscosity, and the injection protocol, such as iodine flux and iodine dose. Adverse reactions are rare and have decreased with the introduction of nonionic contrast agents.
See also Contrast Enhanced Computed Tomography and Abdomen CT.
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Isovist® is a nonionic x-ray contrast agent. Isovist® is suitable for intrathecal applications for example CT myelography, cisternography, the evaluation of cerebrospinal fluid (CSF) circulation and for use in other body cavities. Opacification is directly visible after administration of Iotrolan to the spinal subarachnoid space and various open body cavities. Isovist® flows with the CSF through the arachnoid villi into the venous blood.
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Drug Information and Specification |
| NAME OF COMPOUND |
Iotrolan |
| DEVELOPER |
Bayer Schering Pharma AG |
| INDICATION |
Computed tomography of body cavities and CSF |
| APPLICATION |
Intrathecal, intracavitary |
| PHARMACOKINETIC |
Renal excretion |
| CHEMICAL BOND |
Nonionic dimer |
| OSMOLALITY |
270 or 320 mosm/kgH2O |
| IODINE CONCENTRATION |
240 or 300 mg/mL |
| DOSAGE |
5 - 15 mL/kg |
| PREPARATION |
Ready-to-use product |
| STORAGE |
Store below 30°Celsius (86°Fahrenheit) |
| PRESENTATION |
10 and 20 mL vials |
| DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE NOT A SUBSTITUTE FOR THE ACCOMPANYING
PACKAGE INSERT! |
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| | | | | | Low-Osmolar Contrast Media | |
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| | | •• There are 2 news about 'Low-Osmolar Contrast Media'. | |
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