Medicines Contrast media

Because of its extreme insolubiUty, barium sulfate is not toxic the usual antidote for poisonous barium compounds is to convert them to barium sulfate by administering sodium or magnesium sulfate. In medicine, barium sulfate is widely used as an x-ray contrast medium (see Imaging TECHNOLOGY X-RAY technology). It is also used in photographic papers, filler for plastics, and in concrete as a radiation shield. Commercially, barium sulfate is sold both as natural barite ore and as a precipitated product. Blanc fixe is also used in making white sidewall mbber tires or in other mbber appHcations. 

Strontium, Barium Strontium was discovered near, and named after, the small town of Strontian, Scotland, in 1787. There are no commercial uses for the pure metal, but the carbonate salt, SrC03, is used in the manufacture of glass for color TV picture tubes. Barium is found principally in the minerals witherite (BaC03) and barite (BaSC ), after which it is named. Though water-soluble salts of barium are extremely toxic, barium sulfate is so insoluble that it is used in medicine as a contrast medium for stomach and intestinal X rays. Like strontium, barium metal has no commercial uses, but various compounds are used in glass manufacture and in drilling oil wells. 

Dewey, M., Kaufels, N., Laule, M., et al. (2004) Assessment of myocardial infarction in pigs using a rapid clearance blood pool contrast medium. Magnetic Resonance in Medicine, 51, 703—709. 

Toxicology LD50 (IV, mouse) 2440 mg/kg toxic by ingestion TSCA listed Uses Medicine (x-ray contrast medium) parenteral pharmaceuticals... 

The main physical property of barium which is exploited commercially is its density. Barium concrete is produced using a relatively high concentration of barium compounds to form a material which is very absorptive of radiation and may be used as a radiation shield in reactors. Barium plaster, analogous to the concrete, is used to line hospital and experimental X-ray rooms to absorb radiation and to minimize back scattering. The major use of barium in medicine is as a contrast medium in which role the dense barium atom is X-ray opaque and is used to outline the structure of a hollow organ in the body. 

Barium carbonate can be manufactured from mined heavy spar. From this carbonate a very pure barium sulfate can be prepared. It is called hlancfix and is used as a white pigment in photographic paper and in high-quality paper for maps and playing-cards. Art paper is also made in this way. Barium sulfate is used as an effective contrast medium for X-ray examinations in medicine. The compound has a very low solubility in water and is therefore not poisonous (although barium ions are rather toxic). 

Observational studies Polyvinyl alcohol fibers and films are used in medicine and pharmacology because of their ability to swell, absorb toxic products, decompose necrotic masses, and reduce blood loss [78 ]. A mixture of polyvinyl alcohol with ketoprofen has been used to reduce pelvic pain after uterine artery embolization [79 ] in a randomized prospective study in 80 patients, 40 of whom received ketoprofen mixed with polyvinyl alcohol particles and 40 polyvinyl alcohol alone. During embolization, only five patients recorded a pain score of 1-2. One had an allergic reaction to the contrast medium 13 of the patients who received pol)rvinyl alcohol alone reported severe or very severe pain, compared with none of those who received ketoprofen plus poljrvinyl alcohol. 

Fig.25.8a-c. Left renal fracture in an 11-year-old girl. No associated intra-abdominal or bone lesion was found by CT (a). Delayed scan (b) showed opacification oftheurinomaby the contrast medium. In spite of this severe leak, the urinary excretory system remained patent. Six months later, followup ultrasound showed the fracture between two normalsized segments (c). Excellent function of the left kidney was shown by nuclear medicine studies (not shown)... 

Fig. 10.1a,b. Non-complicated hepatocellular adenoma, a On CT scan during the arterial phase after contrast medium administration the neoplasm becomes homogeneously hyperdense (asterisk) compared to the surrounding liver parenchyma, b Nuclear medicine shows absent uptake of technetium (Tc)-99m sulfur colloid, and the lesion is seen as cold defect ... 

Naturally occurring peptides are substrates of enzymes and ligands of receptors. Many peptides serve as neurotransmitters and hormones. Because they control a variety of physiological processes, they are also implicated in different diseases. For several reasons peptides are usually unsuitable as drugs, so many efforts in medicinal chemistry aim at the development of peptidomimetics with improved properties. In contrast with proteins most peptides of small to medium size - 30 to... 

The substrates of acetylation, schematized in Fig. 13.25, are mainly amines of medium basicity. Very few basic amines (primary or secondary) of medicinal interest have been reported to form N-acetylated metabolites (reaction 1), and when they did, the yields were low. In contrast, a large variety of primary aromatic amines are N-acetylated (reaction 2). Thus, several dmgs such as sulfonamides and para-aminosalicylic acid (30) (PAS Fig. 13.26) are acetylated to large extents, not to mention various carcinogenic amines such as benzidine. 

The main requirement imposed on all polymer biomaterials applied in medicine is a combination of their desired physicochemical and physicomechanical characteristics with biocompatibility. Depending on particular applications, the biocompatibility of polymers can include various requirements, which can sometimes be contradictory to each other. Thns, in the case of artificial vessels, drainages, intraocular lenses, biosensors, or catheters, the interaction of the polymer with a biological medium should be minimized for the rehable operation of the corresponding device after implantation. In contrast, in the majority of orthopedic applications, the active interaction and fusion of an implant with a tissne is required. General requirements imposed on all medical polymers consist in non-toxicity and stability. 

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