X-ray contrast medium

Methylene iodide [75-11-6], CH2I2, also known as diio dome thane, mol wt 267.87, 94.76% I, mp 6.0°C, and bp 181°C, is a very heavy colorless Hquid. It has a density of 3.325 g/mL at 20°C and a refractive index of 1.7538 at 4°C. It darkens in contact with air, moisture, and light. Its solubiHty in water is 1.42 g/100 g H2O at 20°C it is soluble in alcohol, chloroform, ben2ene, and ether. Methylene iodide is prepared by reaction of sodium arsenite and iodoform with sodium hydroxide reaction of iodine, sodium ethoxide, and hydroiodic acid on iodoform the oxidation of iodoacetic acid with potassium persulfate and by reaction of potassium iodide and methylene chloride (124,125). Diiodoform is used for determining the density and refractive index of minerals. It is also used as a starting material in the manufacture of x-ray contrast media and other synthetic pharmaceuticals (qv). 

Low Osmolality Contrast Media. An ideal intravascular CM possesses several properties high opacity to x-rays, high water solubihty, chemical stabihty, low viscosity, low osmolahty, and high biological safety. Low cost and patentabihty are also important for commercial agents. The newer nonionic and low osmolar agents represent an advanced class of compounds in the development of x-ray contrast media. 

The puipose of this article is to discuss whether and how X-ray contrast media may contribute to molecular imaging. 

X-ray contrast media are usually highly concentrated aqueous solutions. A typical product contains 300-370 mg iodine/ml, which corresponds to about 600-800 mg of the iodinated organic molecule per ml. The high concentration of the contrast substance leaves limited room for water (about 0.7 ml per ml of contrast agent) and restricts the design of the molecules because... 

Although a variety of concepts seem to offer opportunities for the development of X-ray contrast media with specificities different from those of the currently used inert small molecules with extracellular distribution one has to consider the following obstacles ... 

In all countries with developed medical care, X-ray contrast media can be expected to be present at appreciable quantities in sewage water. Clara et al [13] detected iopromide at a mean concentration of 3.84 pg in the influent of a WWTP receiving hospital wastewater, while in WWTPs without a hospital within their drainage area this contrast media was not present. lodinated X-ray contrast media are proved to contribute significantly to total absorbable organic iodine in clinical wastewaters up to 130 pg of iodine in the influent of municipal WWTP in Berlin and 10 mg in hospital sewage was detected [23]. 

The removal of X-ray contrast media iopromide was reported to be negligible in conventional WWTP [58]. However, similar to antibiotic trimethoprim, negligible removal in CAS treatment was meliorated to 61% removal by employing nitrifying activated sludge [60]. 

X-ray contrast media Diatrizoate T. versicolor Flasks scale at 30°C 1 mM 80% after 14 days 3,5-Di(acetamido)-2,6-diiodobenzoate 3,5-di (acetamido)-4,6-diiodobenzoate 3,5-di (acetamido)-2-monoiodobenzoate [62]... 

Miyamoto A, Okimoto H, Shinohara H, Shibamoto Y (2006) Development of water-soluble metallofullerenes as X-ray contrast media. Eur. Radiol. 16 1050-1053. 

Recently, Duirk et al. [34] showed evidence that iodinated X-ray contrast media (ICM), such as iopamidol, constitute an iodine source to form iodo-THM DBFs, e.g., dichloroiodomethane, and iodo-acid DBFs, e.g., iodoacetic acid, in chlorinated and chloraminated drinking waters. However, the complete reaction pathway is not fully understood yet, and it is under further investigation. Chloraminated and chlorinated source waters with iopamidol were genotoxic and cytotoxic in mammalian cells. This is in agreement with the previously reported high genotoxicity and cytotoxicity of the iodo-acids and iodo-THMs [20, 21]. 

The pharmacokinetics of X-ray contrast agents used in angiography and urography are practically identical. These are characterized by extracellular distribution followed by renal excretion by glomerular filtration. The terminal half-life is approx. 1.5 h. An overview of the existing data on pharmacokinetics of X-ray contrast media in humans has been given by Bourin et al. [5]. 

Temes T.A. and R. Hrrsch (2000). Occurrence and behavior of x-ray contrast media in sewage facihties and the aquatic environmet. Environmental Science and Technology 34 2741-2748. 

X-ray contrast media (73GEP2219707,74USP3795698). Drugs utilized in the treatment of asthma usually affect cardiovascular, as well as bronchial, adrenergic receptors. Considerable effort has been applied to the preparation of compounds that exhibit selectivity for the adrenergic receptors that predominate in the lung. Quinterenol (96) has shown promise in this direction (66NEP6601980). 

X-ray-contrast media, analgesics, antipyretics, antirheumatics and some other pharma-... 

Jakobsen JA, Berg KJ, Kjaersgaard R et al. Angiography with nonionic X-ray contrast media in severe chronic renal failure renal function and contrast retention. Nephron 1996 73 549-556. 

Bentley A, Piper K. 1987. X-ray contrast media. Part 1. Barium sulfate preparations. Pharm J 238 138-139. 

The most common X-ray agents are based on highly soluble tri-iodo aryl derivatives. However, some metal-containing X-ray contrast media exist. The most common is barium sulfate, administered as a suspension to provide contrast in imaging the... 

Yu SB, Watson AD. Metal-based X-ray contrast media. Chem. Rev. 1999 99 2353-2378. 

Less extensive binding of drugs to plasma proteins is generally without clinical importance but there is a significant risk of elevation of plasma bilirubin (in the neonate) following its displacement from protein binding sites by vitamin K, x-ray contrast media or indomethacin. 

Bilirubin is displaced from its binding protein by sulphonamides, vitamin K, X-ray contrast media or indomethacin in the neonate this may cause a significant risk of kernicterus, for its capacity to metabolise bilirubin is immature. 

Displacement of bilirubin from its albmnin bond. Various endogenous substances (e. g. long-chain fatty acids and bile acids) or exogenous compounds (e. g. medication, such as ampicillin, ajma-line, quinidine, furosemide, indomethadn, probenecid, rifampicin, sulphonamide etc., and X-ray contrast media) can compete with bilirubin, not only with respect to its specific binding site, but also for its carrier protein. 

The radio-opacity of X-ray contrast media depends on the fact that they contain substances that have high atomic numbers, which absorb X-rays. Bismuth, now largely obsolete, has an atomic number of 83, barium 56. Since the soluble salts of barium are poisonous, the insoluble salt, barium sulfate, is used as a suspension. Soluble contrast media are based on iodine, which has an atomic number of 53. This means that in principle they can have the various adverse effects of other iodine-containing compounds. 

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