Contrast media toxicity

Visual evoked responses 20 hours after myelography can be delayed, with a correlation with the severity of headache after myelography the delay in visual-evoked response is less marked with iopamidol than with metrizamide. It has been suggested that this technique may be useful in the assessment of myelographic contrast media toxicity (79). 

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. 

In a different way, metallic-core nanoparticles [346-349] (prepared cf. Section 3.10) equipped with biocompatible coats such as L-cysteine or dextrane may be exploited for highly efficient and cell-specific cancer cell targeting, i.e., for improving diagnosis and therapy of human cancer. In a recent proof-of-principle experiment an unexpectedly low toxicity of the L-cysteine-covered cobalt nanoparticles was demonstrated [433] For diagnostic purposes, it is expected to use the advantageous magnetic properties of the metallic-core nanoparticles to obtain a contrast medium for MRI with considerably increased sensitivity, capable to detect micro-metastases in the environment of healthy tissues [434 37]. 

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. 

Although barium ion is highly toxic, the insolubility and inertness of barium sulphate permits its wide use, given by mouth, as an opaque contrast medium to in-... 

Many causes of acute spinal cord infarction (of arterial and venous origin) have been reported (Table 17.2). They include diseases of the aorta and aortic surgery, thromboembolic events and cartilaginous disc embolism, vasculitis, coagulopathy, radiation-induced vasculopathy, toxic effects of contrast medium, epidural anesthesia, periradicu-lar nerve root therapy with crystalline corticoids, decompression illness, shock or cardiac arrest, lumbar artery compression and other etiologies... 

Hearing disturbances attributable to contrast agents are extremely rare. The hearing loss in this patient developed more than 1 hour after the injection of iohexol, without any evidence of other causes. The authors suggested that the hearing disturbance might have been attributable to cochlear impairment caused by a delayed allergic reaction or chemical toxicity of the contrast medium. 

Enzymuria has been reported after the intravascular administration of high-osmolar or low-osmolar contrast media (180). The study suggested that the brush-border enzyme gamma-glutamyl transpeptidase is a better marker for tubular toxicity due to contrast media than alanine aminopeptidase. However, no relation has been established between a reduction in glomerular filtration rate, a rise in serum creatinine (the characteristic features of contrast nephrotoxicity), and the presence of enzymuria. It has been argued that the detection of urinary enzymes is of httle importance to the clinical assessment and management of contrast medium nephrotoxicity (161). 

Prior interleukin-2 therapy can induce atypical contrast medium hypersensitivity in the form of toxic recall reactions of various types (SEDA-17, 537), and these cannot be prevented by glucocorticoid premedication (315). 

Barium sulfate may also be used safely as an X-ray contrast medium as its very low solubility is reflected by low toxicity. Likewise, the solubility of barium sulfate in whole body water is insufficient to cause any toxic effects (Barke 1970). The extent of absorption of barium (determined by renal excretion) following administration of barium sulfate preparations ranged from 18 to 35 jg, which was equivalent to an absorption rate of 0.18-0.26% (Clave et al. 1987). 

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

Soluble barium salts are highly toxic and the use of barium sulfate as a contrast medium for radiography depends entirely on its highly insoluble nature as well as the density of the barium atom. 

Systemic toxic reactions to local anesthetic due to an excessive dose and/or accidental intravenous injection of the drug. Repeated attempts to aspirate the syringe during injection should be made to ascertain that the bevel of the needle is not in a blood vessel. Prior to injection of local anesthetic and/or ethanol near vessels, 2 ml of contrast medium should be injected as a test. If the contrast medium is not seen at the intended site of injection on the CT scan, thereby implying dispersal of contrast medium intravascularly (or even intrathe-cally), the procedure should be discontinued. 

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). 

Strontium is quite common in seawater. Some organisms use strontium sulfate as a skeletal material. Strontium is added to the water in aquariums, as the decorative stony corals need it. Strontium has no function in the human body. (It is the most abundant element in the human body without a known function there.) Nor is barium essential for Hfe indeed it is toxic. The symptoms of barium poisoning are colic, diarrhoea, vomiting and paralysis. The content of barium in food plants is as a rule low (part per million levels) but there is an exception Brazil nuts may contain as much as 1% barium. The metabolism is stimulated by barium, but to such a high degree that the heart begins to beat erratically (ventricular fibrillation). Barium salts are thus toxic to humans, but the use of barium sulfate as an X-ray contrast medium is accepted because of its very low solubility. 

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. 

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