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At least 127 records · Page 7Linked to original sources
PubMed1997

An overview of the clinical pharmacokinetics of x-ray contrast media.

Pharmacokinetic studies of contrast media are usually performed as preclinical trials in anaesthetised animals; however, results in humans have also been reported for this type of compounds. This paper reviews the existing data about x-ray contrast media in humans. In some cases, animal data are used in areas where no human data are available. The administration of contrast media is generally made via the intravenous, intra-arterial or intrathecal route. Diagnostic procedures are based on differential distribution to organs and between normal and abnormal tissue. Data are available for iodixanol, iohexol, iopamidol, iopromide, iothalamate and ioxaglate, but the kinetic distribution of all contrast media is similar. With the exception of biliary contrast agents, all compounds display limited plasma protein binding and do not undergo biotransformation. From the pharmacokinetic viewpoint, the main area of interest for these compounds is elimination. The majority of the data were obtained with iopamidol (of which 66 to 72% of the dose is excreted in the urine), iohexol, ioxaglate and iopromide. Some studies were performed in patients with renal impairment: in this case, metabolic clearance was abnormally elevated, suggesting the existence of significant compensatory factors such as hepatic metabolism, enterohepatic circulation and biliary elimination. New compounds, such as iodinated polymers for x-ray perfusion imaging and iopromide- or metrizamide-containing liposomes allowing liver enhancement are discussed.

Animals↗
PubMed1987

Role for intrarenal adenosine in the renal hemodynamic response to contrast media.

The intrarenal injection of contrast media results in a transient fall in renal blood flow (RBF) and a decrease in glomerular filtration rate (GFR). These effects are enhanced by dietary sodium restriction and attenuated by sodium loading. A similar sodium-dependent response of RBF and GFR occurs with the intrarenal injection of adenosine. In view of these similarities, we sought to determine whether endogenous adenosine is involved in the renal hemodynamic response to contrast media. The intrarenal injection of contrast media (meglumine-Na diatrizoate, 76%) in six sodium-depleted, anesthetized dogs resulted in a 17% +/- 4% decrease in RBF and a 31% +/- 5% decrease in GFR. The infusion of the adenosine receptor antagonist, theophylline (5 mumol/min), reduced the decrease in RBF to 6% +/- 2% and in GFR to 12% +/- 3% of control values. During the intrarenal infusion of dipyridamole (24 micrograms/kg/min), a potentiator of adenosine through its action to inhibit the cellular uptake of nucleosides, the hemodynamic response to contrast media was greater; RBF fell 25% +/- 4% and GFR fell 44% +/- 7%. In addition, the urinary excretion of endogenous adenosine increased after the injection of contrast media (388 +/- 79 vs. 830 +/- 231 nmol/min). In summary, the contrast media-induced fall in RBF and GFR was attenuated by theophylline and augmented by dipyridamole, and the administration of contrast media resulted in an increase in the excretion of endogenous adenosine. These results support the hypothesis that endogenous adenosine is involved in the renal hemodynamic response to contrast media.

Adenosine↗
PubMed2006

Recognition and management of contrast media extravasation.

Intravenous contrast agents are frequent adjuncts used in diagnostic imaging. Despite the well-recognized complications of contrast media extravasation, its treatment remains an enigma to many. This article reviews the recognition, prevention and treatment options, with a summary of the contrast media extravasation policy implemented in our department.

Adverse Drug Reaction Reporting Systems↗
PubMed2004

Effects of contrast media on renal function in patients with cirrhosis: a prospective study.

Patients with cirrhosis are frequently submitted to radiological procedures that require the administration of contrast media. Contrast media is a well-known cause of renal failure, particularly in the presence of some predisposing conditions. However, it is not known whether cirrhosis constitutes a risk factor for contrast media-induced renal failure. The aim of this study was to assess the possible nephrotoxicity of contrast media in patients with cirrhosis. In a first protocol, renal function was evaluated with sensitive methods (glomerular filtration rate using iothalamate I 125 clearance and renal plasma flow using iodohippurate I 131 clearance) before and 48 hours after the administration of contrast media in 31 patients with cirrhosis (20 with ascites, 5 with renal failure). Solute-free water clearance, urine sodium, prostaglandins, and markers of tubular damage were also measured. The administration of contrast media was not associated with significant changes in renal function tests, neither in the whole group of patients nor in patients with ascites or renal failure. Urinary prostaglandin E2 and N-acetyl-beta-D-glucosaminidase increased significantly, but sodium and solute-free water excretion remained unchanged. In a second protocol, a different series of 60 patients with cirrhosis and renal failure were examined prospectively. No patient had renal failure due to contrast media. Only in 1 patient with septic shock was contrast media a possible contributing factor. In conclusion, the administration of contrast media is not associated with adverse effects on renal function in patients with cirrhosis. Cirrhosis does not appear to be a risk factor for the development of contrast media-induced nephrotoxicity.

Acetylglucosaminidase↗
PubMed1998

High-resolution functional magnetic resonance imaging of the rat brain: mapping changes in cerebral blood volume using iron oxide contrast media.

Contrast-enhanced magnetic resonance imaging was used to produce high-resolution activation maps reflecting local changes in cerebral blood volume after a simple sensory stimulus. Activation of the forelimb region of the somatosensory cortex was performed in alpha-chloralose-anaesthetized rats with an electrical stimulus (5 V, 3 Hz) delivered through needle electrodes placed subcutaneously on the left forelimb. A gradient echo magnetic resonance imaging sequence, sensitive to changes in the relative amount of deoxyhemoglobin within the cerebral vasculature, produced a 4.05%+/-1.69% increase in signal intensity. This effect was enhanced with an injection of an intravascular iron oxide contrast agent (Combidex, Advanced Magnetics), resulting in a 9.11%+/-1.52% decrease in signal intensity.

Animals↗
PubMedDate not supplied

[Prevention of acute tubular necrosis caused by the administration of non-ionic radiologic contrast media].

Radiographic contrast agents can cause acute renal failure that may be due to acute tubular necrosis (ATN). We prospectively studied 45 patients with risk factors for ATN who were undergoing computed tomography with three nonionic contrast agents (ioversolo, iobitridolo and iodixanolo). Patients were randomly assigned either to receive preventive management (0.45% saline intravenously, before and after administration of the contrast agent; mannitol 20% 250 mL i.v. 60 min before and 60 min after the contrast agent; furosemide 80 mg i.v. 30 min before the contrast agent; dopamine 3 g/Kg/min i.v. after administration of the contrast agent for 24 hours) or to receive placebo. Prophylactic management prevents the reduction in renal function induced by ioversolo, iobitridolo and iodixanolo, three noninonic contrast agents in patients with risk factors for ATN.

Adult↗
PubMed1993

Nonionic contrast media. Procoagulants or clotting innocents?

OBJECTIVES: Compared with ionic contrast media, nonionic contrast media cause fewer adverse reactions, including hemodynamic and electrophysiologic complications, and are better tolerated by patients. However, concern as to whether nonionic agents are associated with more thromboembolic complications has been raised in recent years. This article reviews in-vitro and in-vivo coagulation studies with nonionic contrast media, including the authors' current study using blood samples from percutaneous transluminal coronary angioplasty (PTCA) patients. METHODS: Articles for this review were selected on the basis of providing viewpoints representative of both sides of the clotting controversy involving nonionic contrast media. In addition, articles were selected that, in toto, include the several relevant aspects of thrombosis during PTCA: whole blood clotting, angiography catheters, angiography syringes, rheology, and vascular endothelium. The preliminary work described used platelet adhesion/aggregation to a collagen-coated surface under controlled conditions of heparinized, whole blood flow. Adhesion/aggregation was quantified by digital analysis of real-time images obtained by epifluorescence videomicroscopy. In parallel studies, changes in markers (membrane glycoproteins) of platelet activation were measured using whole blood flow cytometry. RESULTS: Although nonionic contrast media are weaker anticoagulants than ionic contrast media, no convincing evidence demonstrates that they are procoagulant. On the contrary, in-vitro studies suggest that ionic media may weaken the antithrombotic properties of vascular endothelium by direct endothelial injury. Certain clinical trials of PTCA patients substantially challenge the use of nonionics. Yet, Grabowski et al found no evidence of platelet activation by ioxaglate or iohexol in preliminary work. This result was obtained with two of the most sensitive platelet assays available: flowing whole blood aggregometry and whole blood flow cytometry. Attention should be given to the adequacy of heparinization in future clinical studies. CONCLUSIONS: Nonionic contrast media are not procoagulant in vitro in the hands of most research groups. The focus of current controversy, therefore, is whether there is a clinical and in-vivo difference in thrombotic events seen with nonionic versus ionic media during PTCA. Elements in this controversy include platelet activation, blood-foreign surface (catheter and syringe) interaction, rheology, vascular endothelium, and adequacy of heparinization.

Angioplasty, Balloon, Coronary↗
PubMed1997

Intravascular contrast media: can we justify the continued use of ionic contrast agents?

Cost has been the major factor preventing the universal conversion to non-ionic contrast agents. We assessed the costs and potential benefits of making this change in our department. During a 10-month-period the use of all intravascular contrast agents and reaction rates were audited prospectively. One thousand three hundred and ninety-four examinations were included. A local protocol for the use of ionic and non-ionic contrast media was already in place, based on the Royal College of Radiologists Guidelines. For each patient the contrast agent used, risk factors, and presence or absence of a contrast reaction were recorded. Non-ionic contrast agent usage exceeded ionic by a factor of 10. Patients receiving ionic agents intravenously had a reaction rate of 16.8% compared with 2.7% for non-ionic contrast media. The use of ionic contrast media was subsequently suspended and the effect of this on overall costs assessed by retrospectively and prospectively analysing hospital expenditure on contrast agents. No increase in costs was found. The reasons for this are two-fold. Firstly in our institution the protocol in place and the nature of the workload resulted in relatively small volumes of ionic contrast media being used compared with non-ionic agents. Secondly, since our department is a bulk purchaser of non-ionic agents, substantial discounts could be negotiated. The benefits of non-ionic contrast media are well recognized and our experience suggests that cost may no longer be a barrier to conversion to these lower risk agents.

Contrast Media↗
PubMedDate not supplied

ESUR guidelines on contrast media.

Since 1996 the Contrast Media Safety Committee of the European Society of Urogenital Radiology has released 15 guidelines regarding safety in relation to the use of radiographic, ultrasonographic, and magnetic resonance contrast media. The guidelines have been well received by the radiologic community in Europe and all over the world and comprise current standards for good practice at many institutions. The present report is an overview of the work accomplished by the European Society of Urogenital Radiology over the past 8 years. The committee has covered renal and nonrenal adverse events and other aspects of contrast media.

Contrast Media↗
PubMed1987

[Pharmacokinetics and tolerance of roentgen contrast media].

The improved tolerance of nonionic contrast media compared with conventional contrast media is mainly due to their lower osmolality and reduced allergoid potential. Tolerance advantages that have been definitely proven are, for example, low-pain contrast medium injection and superior systemic tolerance; side effects of an allergic pattern occur less often. Animals experiments have established that nonionic contrast media exercise a comparatively lower influence on the cardiovascular system. The haemodynamics of pulmonary circulation are less adversely affected on intravenous bolus injection. Reduced potential risk is to be expected especially in cardiac and bronchopulmonary high-risk patients. The reduced nephrotoxicity of nonionic contrast media was definitely established by clinical studies. Further systematic studies will however be required to provide an answer to the question whether this also entails a reduction in the incidence of renal failures induced by contrast media.

Angiography↗
PubMedDate not supplied

Contrast media for cardiothoracic MR imaging.

Contrast media have been used for the study of disease of the thorax. Most experience has consisted of the use of MR contrast media for improving the delineation of acute myocardial infarction, for demarcating the area of acute myocardial ischemia, and for demonstrating the area of potentially jeopardized myocardium after acute coronary occlusion. Contrast agents demonstrate the ischemic or jeopardized area as a zone of decreased signal intensity to normal myocardium. On the other hand, the magnetic susceptibility agents demonstrate the ischemic or jeopardized area as a zone of increased signal intensity to normal myocardium. Little experience exists concerning the use of MR contrast media for enhancing mediastinal and lung masses. The few reports to date demonstrate that contrast media can improve the conspicuity of thoracic masses. A new nonionic contrast medium, gadodiamide injection, has been shown to considerably increase S/N and C/N of thoracic masses. Further studies are necessary to define the role of MR contrast media in the evaluation of myocardial ischemia and thoracic masses in clinical practice.

Animals↗