Radiographic contrast media

Comprehensive Study of Drug-Induced Pruritus Based on Adverse Drug Reaction Report Database

Drug-induced pruritus triggers a desire to scratch, thereby diminishing one's quality of life. Certain instances of this phenomenon follow complex mechanisms of action that diverge from histamine-mediated pathways, known contributors to pruritus. However, investigations into the relationship between drugs and pruritus are limited. In this study, data mining techniques were employed to comprehensively analyze the characteristics of drugs linked to pruritus, using the FDA's Adverse Event Reporting System (FAERS) data. Reports linked to pruritus demonstrated noteworthy differences in gender, age, and weight when compared with non-pruritus cases. Among the leading candidates for drugs prompting pruritus were ophthalmic drugs, systemic antibacterials, contrast media, dermatological antifungals, and dermatological preparations. A principal component analysis showed that the second principal component served as an indicator for distinguishing between onsets at mucous membranes or the skin's surface. Additionally, the third principal component functioned as an indicator for categorizing administration methods as either invasive or noninvasive. Furthermore, a hierarchical cluster analysis conducted on these obtained principal components revealed the potential for classifying drugs based on the site of pruritus onset and the method of drug administration. These findings contribute to the development of targeted prevention and treatment strategies for avoiding pruritus in clinical practice.

Validation of Practical Pathway in Patients With Anaphylaxis to Low Osmolar Contrast Media: A Retrospective Cohort Study

BACKGROUND

An optimal strategy for choosing safe alternative low osmolar contrast media (LOCM) has not yet been established in patients with a history of LOCM-induced anaphylaxis.

OBJECTIVES

To validate the practical pathway in patients with anaphylaxis to LOCMs and to compare 2 different doses of challenge testing with skin test-negative LOCM.

METHODS

A retrospective cohort study was performed in patients with LOCM-induced anaphylaxis. Patients were challenged with intravenous LOCMs showing negativity in the skin test according to 2 different protocols: low-dose and high-dose (maximum dose 10 and 30 mL, respectively). Challenge-negative LOCMs were selected for use during computed tomography scans, and patients received intravenous pretreatment with 4 mg chlorpheniramine and 40 mg methylprednisolone.

RESULTS

Of the 110 challenge tests, there were 4 (3.6%) positive challenges. Among 106 enhanced computed tomography scans performed using challenge-negative LOCMs, breakthrough reactions occurred in 8 (7.6%). Breakthrough reaction rates were not statistically different between the 2 protocols (8.9% and 6.0% in the low-dose challenge and the high-dose challenge, respectively). Compared with the low-dose protocol, the number needed to test of the high-dose challenge test decreased 2.5-fold. Moreover, none of the patients in the high-dose challenge group incurred severe reactions during computed tomography scans with challenge-negative LOCM, whereas 80% of reactions were severe in the low-dose challenge group.

CONCLUSIONS

We validated a pathway consisting of a battery of skin testing to LOCMs and challenge with skin test-negative LOCM in patients with LOCM-induced anaphylaxis.

Evaluation of N-(6-[18F]Fluoropyridin-3-yl)glycine PET renography to detect renal function progression in a rat model of diabetic nephropathy

OBJECTIVE

Given the limitation of biomarkers to predict the renal function progression in diabetic nephropathy, N-(6-[¹⁸F]Fluoropyridin-3-yl)glycine (6-[¹⁸F]FPyGly) was used to evaluate renal function progression in a rat model of diabetic nephropathy.

METHODS

Twenty male Sprague-Dawley rats were randomly divided into four groups, including the healthy control group (HC group), diabetic nephropathy group (DNM group), routine diet treated diabetic nephropathy group (RDNM group), and high fat/high sucrose -diet-fed diabetic nephropathy group (HDNM group). All renal function parameters were determined from animal PET renograms. P and T_max represent the curve peak counts and the time to the curve peak counts of 6-[¹⁸F]FPyGly in kidneys after injection, C_1/2 and the 15 min/Peak ratio represent the time from peak to 1/2 peak in the clearance phase, and the ratio of the curve counts at 15 min to the curve peak counts.

RESULTS

P, T_max, C_1/2, and 15 min/peak ratio of each rat were significantly correlated with S-Cr, BUN. There were significant differences in T_max, P, serum creatinine (SCr), and blood urea nitrogen (BUN) levels between HC and DNM groups. P and the 15 min/Peak ratio were significantly different among DNM, RDNM, and HDNM groups, while T_max and C_1/2 were only significantly different between DNM and RDNM or HDNM groups. There only was a significant difference in BUN between the DNM and HDNM groups.

CONCLUSION

The renal function parameters P, T_max, C_1/2 and 15 min/peak value obtained by dynamic renal imaging based on 6-[¹⁸F]FPyGly could reflect changes of renal function in rats, which had a good correlation with SCr and BUN, and showed more efficient in the diagnosis of diabetic nephropathy and renal function classification than SCr and BUN.

Contrast Media Adverse Drug Reactions in Highly Polluted Environment

Iodinated- (ICM) and gadolinium-based (GCM) contrast media are used in radiology imaging techniques, such as computer tomography (CT) and magnetic resonance (MR), respectively. The paper aims to analyze the adverse drug reactions of ICM and GCM on different sites of the body in a highly polluted environment. We analyzed the pharmacovigilance in contrast media on the basis of reports submitted to the Regional Center for Monitoring of Adverse Drug Reactions (ADR) at the Department of Clinical Pharmacology in Wrocław. Safety profiles were compared between different ICM and GCM and at the system organ level using the proportional reporting ratio (PRR). We analyzed 124 reports of adverse reactions related to contrast agents between 2006 and 2021. Our findings revealed that ADR combinations occurred more frequently after the use of iodinated contrast agents (72.08%) than gadolinium contrast agents (27.92%). Iomeprol and Iopromide were identified as the most frequently reported media. Each medium presented a different safety profile. Skin disorders are the most common adverse drug reactions among patients using both iodine- and gadolinium-based contrast media. Gadolinium-based contrast agents are characterized by similar organ toxicity. Conversely, iodine-based contrast agents are more diverse—some of which show tissue specificity, such as Iodixanol for the gastrointestinal system or Iohexol for the respiratory tract. This study shows relatively high occurrence of respiratory tract related ADRs in Wrocław. We also prove that it is possible to choose the most optimal contrast agent for patients with specific organ site problems to omit the possible complications.

Clinical safety evaluation of contrast agents based on real-world evidence

WHAT IS KNOWN AND OBJECTIVE

This study was aimed at comparing the adverse drug reactions (ADRs) arising from the use of iodinated contrast medium (ICM) and gadolinium-based contrast media (GBCM), and to provide a basis for the clinical selection of contrast media.

METHODS

Retrospective data for ADR cases occurring from the use of ICM or GBCM during enhanced scanning in computed tomography and magnetic resonance imaging were collected between June/2013 and May/2020 from Wenling Hospital of Traditional Chinese Medicine. Chi-square tests were performed based on the characteristics of patients and the classification of contrast medium. Bonferroni correction was applied to the statistical analyses with multiple comparisons of proportions.

RESULTS

Among 27,328 patients who were subjected to enhanced CT scanning, 207 cases (0.76%) showed ICM-related ADRs. Among 16,381 patients who were subjected to enhanced MRI scanning, 25 cases (0.15%) showed ADRs related to GBCM. The incidence of ADR induced by GBCM was significantly lower than ICM-induced ADR (p < 0.01). There were no significant differences in the incidence among different types of ICM, including ioversol and iodixanol, as well as iodixanol from different manufacturers (p > 0.05). Interestingly, the ADR incidence of ICM seemed to be associated with gender, with a significantly higher incidence in females than in male patients, and it was also associated with the age, with a lower occurrence in older (>44 years) compared to younger patients.

WHAT IS NEW AND CONCLUSION

With respect to ADR incidence, the safety profile of ICM of different types and different manufacturers was found to be similar in clinical use, warranting no need of specifically choosing imported or more expensive products. While choosing contrast medium type for clinical use, attention should be paid to certain populations, especially to younger and female patients when the patients are about to undergo a contrast-enhanced examination.

The Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) is Protective in Inflammation and Oxidative Stress-Induced Damage in the Kidney

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide with a widespread distribution throughout the entire body including the urinary system. PACAP exerts protective actions in different injury models related to several organ systems. Its protective effect is mainly based on its antiapoptotic, anti-inflammatory and antioxidant effects. The present review aims to summarize the effects of PACAP in pathologies associated with inflammation and oxidative stress-induced damage in the kidney. Both in vitro and in vivo data are available proving its protective actions against oxidative stress, hypoxia, renal ischemia/reperfusion, diabetic nephropathy, myeloma kidney injury, amyloidosis and different types of drug-induced nephropathies. Data showing the nephroprotection by PACAP emphasize the potential of PACAP’s therapeutic use in various renal pathologies.

Radiocontrast Agent Diatrizoic Acid Induces Mitophagy and Oxidative Stress via Calcium Dysregulation

Contrast-induced acute kidney injury (CI-AKI) is the third most common cause of hospital associated kidney damage. Potential mechanisms of CI-AKI may involve diminished renal hemodynamics, inflammatory responses, and direct cytotoxicity. The hypothesis for this study is that diatrizoic acid (DA) induces direct cytotoxicity to human proximal tubule (HK-2) cells via calcium dysregulation, mitochondrial dysfunction, and oxidative stress. HK-2 cells were exposed to 0–30 mg I/mL DA or vehicle for 2–24 h. Conversion of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and trypan blue exclusion indicated a decrease in mitochondrial and cell viability within 2 and 24 h, respectively. Mitochondrial dysfunction was apparent within 8 h post exposure to 15 mg I/mL DA as shown by Seahorse XF cell mito and Glycolysis Stress tests. Mitophagy was increased at 8 h by 15 mg I/mL DA as confirmed by elevated LC3BII/I expression ratio. HK-2 cells pretreated with calcium level modulators BAPTA-AM, EGTA, or 2-aminophenyl borinate abrogated DA-induced mitochondrial damage. DA increased oxidative stress biomarkers of protein carbonylation and 4-hydroxynonenol (4HNE) adduct formation. Caspase 3 and 12 activation was induced by DA compared to vehicle at 24 h. These studies indicate that clinically relevant concentrations of DA impair HK-2 cells by dysregulating calcium, inducing mitochondrial turnover and oxidative stress, and activating apoptosis.

The molecular mechanism of contrast-induced nephropathy (CIN) and its link to in vitro studies on iodinated contrast media (CM)

Iodinated contrast media (iodinated CM) have increased ability to absorb x-rays and to visualize structures that normally are impossible to observe in a radiological examination. The use of iodinated CM may destory renal function, commonly known as contrast-induced nephropathy (CIN), which can result in acute renal failure (ARF). This review article mainly focuses on the following areas: (1) classifications of iodinated CM: ionic or non-ionic, high-osmolarity contrast media (HOCM), low-osmolarity contrast media (LOCM) and iso-osmolarity contrast media (IOCM); (2) an introduction to the physical and chemical properties of the non-ionic iodinated CM; (3) the management of anaphylactic reaction by iodinated CM; (4) a suggested single injection of adult doses and maximum dose for non-ionic iodinated CM; (5) the molecular mechanism of contrast-induced nephropathy (CIN); (6) In vitro studies on iodinated CM. Based on above information, this review article provide an insight for understanding the drug safety of iodinated CM.

Skeletal muscle analyses: agreement between non-contrast and contrast CT scan measurements of skeletal muscle area and mean muscle attenuation

Low skeletal muscle area (SMA) and muscle radiation attenuation (MRA) have been associated with poor prognosis in various patient populations. Both non-contrast and contrast CT scans are used to determine SMA and MRA. The effect of the use of a contrast agent on SMA and MRA is unknown. Therefore, we investigated agreement between these two scan options. SMA and MRA of 41 healthy individuals were analysed on a paired non-contrast and contrast single CT scan, and agreement between paired scan results was assessed with use of Bland-Altman plots, intraclass correlation coefficients (ICCs), standard error of measurements (SEM) and smallest detectable differences at a 95% confidence level (SDD₉₅ ). Analyses were stratified by tube voltage. Difference in SMA between non-contrast and contrast scans made with a different tube voltage was 7·0 ± 7·5 cm² ; for scans made with the same tube voltage this was 2·3 ± 1·7 cm² . Agreement was excellent for both methods: ICC: 0·952, SEM: 7·2 cm² , SDD₉₅ : 19·9 cm² and ICC: 0·997, SEM: 2·0 cm² , SDD₉₅ : 5·6 cm² , respectively. MRA of scans made with a different tube voltage differed 1·3 ± 11·3 HU, and agreement was poor (ICC: 0·207, SEM: 7·9 HU, SDD₉₅ : 21·8 HU). For scans made with the same tube voltage the difference was 6·7 ± 3·2 HU, and agreement was good (ICC: 0·682, SEM: 5·3 HU, SDD₉₅ : 14·6 HU). In conclusion, SMA and MRA can be slightly influenced by the use of contrast agent. To minimise measurement error, image acquisition parameters of the scans should be similar.

How to Manage (Treat) Immediate-type Adverse Reactions to GBCA

Acute nonrenal adverse reactions to gadolinium-based contrast agents are infrequent and occur often unexpectedly. Most reactions are self-limiting and do not require treatment. The remaining adverse reactions are either moderate or severe and they require medical treatment. Prompt and effective treatment is very important and requires knowledge, training, and preparation.

Myelography Iodinated Contrast Media. 2. Conformational Versatility of Iopamidol in the Solid State

The phenomenon of polymorphism is of great relevance in pharmaceutics, since different polymorphs have different physicochemical properties, e.g., solubility, hence, bioavailability. Coupling diffractometric and spectroscopic experiments with thermodynamic analysis and computational work opens to a methodological approach which provides information on both structure and dynamics in the solid as well as in solution. The present work reports on the conformational changes in crystalline iopamidol, which is characterized by atropisomerism, a phenomenon that influences both the solution properties and the distinct crystal phases. The conformation of iopamidol is discussed for three different crystal phases. In the anhydrous and monohydrate crystal forms, iopamidol molecules display a syn conformation of the long branches stemming out from the triiodobenzene ring, while in the pentahydrate phase the anti conformation is found. IR and Raman spectroscopic studies carried out on the three crystal forms, jointly with quantum chemical computations, revealed that the markedly different spectral features can be specifically attributed to the different molecular conformations. Our results on the conformational versatility of iopamidol in different crystalline phases, linking structural and spectroscopic evidence for the solution state and the solid forms, provide a definite protocol for grasping the signals that can be taken as conformational markers. This is the first step for understanding the crystallization mechanism occurring in supersaturated solution of iopamidol molecules.

Myelography iodinated contrast media. I. Unraveling the atropisomerism properties in solution

The present work reports a thorough conformational analysis of iodinated contrast media: iomeprol, iopamidol (the world's most utilized contrast agent), and iopromide. Its main aim is the understanding of the complex structural features of these atropisomeric molecules, characterized by the presence of many conformers with hindered rotations, and of the role of atropisomerism in the physicochemical properties of their aqueous solutions. The problem was tackled by using an extensive analysis of (13)C NMR data on the solutions of whole molecules and of simple precursors in addition to FT-IR investigation and molecular simulations. This analysis demonstrated that out of the many possible atropisomers, only a few are significantly populated, and their relative population is provided. The conformational analysis also indicated that the presence of a sterically hindered amidic bond, allowing a significant population of cis forms (E in iopromide and exo in iomeprol), may be the basis for an increased thermodynamic solubility of concentrated solutions of iomeprol.

Adverse reactions to iodinated contrast media

The use of iodinated contrast agents for angiography dates back to the 1920s. With over 75 million contrast-requiring procedures performed annually worldwide, it is important to understand the risk factors, pathogenesis, diagnosis, prevention, and treatment of adverse reactions caused by iodinated contrast media (ICM). As contrast media have evolved from ionic, high-osmolality to nonionic, low-osmolality formulations the risk of reactions has decreased over time; however, no pretreatment protocol has been shown to eliminate all repeat reactions. Clinical alertness and early recognition of adverse reactions is of paramount importance and key for appropriate management of these patients. In this article, we review the most recent literature regarding adverse reactions to ICM and provide an insight into the pathogenesis, clinical presentation, pretreatment, and management of contrast-related reactions.

Pituitary adenylate cyclase-activating polypeptide prevents contrast-induced nephropathy in a novel mouse model

We determined whether pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) prevents contrast-induced nephropathy using human renal proximal tubule epithelial (HK-2) cells and homozygous endothelial nitric oxide synthase-deficient (eNOS(-/-)) mice as a novel in vivo model. Cultured HK-2 cells were pretreated with 10(-9)-10(-6) mol/L PACAP or vasoactive intestinal peptide (VIP) for 1 h, and then exposed to ionic (Urografin) or nonionic (iohexol) contrast media at 50 mg iodine/mL for 24 h. Male eNOS(-/-) mice received Urografin (1.85 g iodine/kg) intravenously after water deprivation for 24 h, and PACAP38 (10 μg) intraperitoneally 1 h before and 12 h after Urografin injection. Urografin and iohexol increased lactate dehydrogenase and kidney injury molecule 1 in the culture medium, induced apoptosis, and inhibited cell proliferation in HK-2 cell cultures. PACAP38 and VIP reduced these changes in a dose-dependent manner. PACAP38 was more potent than VIP. In eNOS(-/-) mice, Urografin raised serum creatinine and cystatin C levels, caused renal tubule damage, induced apoptosis, and promoted neutrophil influx. Urografin also increased kidney protein levels of proinflammatory cytokines, and kidney mRNA levels of proinflammatory cytokines, kidney injury biomarkers, and enzymes responsible for reactive oxygen and nitrogen species. PACAP38 significantly reduced these Urografin-induced changes in eNOS(-/-) mice. This study shows that both Urografin and iohexol are toxic to HK-2 cells, but Urografin is more toxic than iohexol. Urografin causes acute kidney injury in eNOS(-/-) mice. PACAP38 protects HK-2 cells and mouse kidneys from contrast media and is a potential therapeutic agent for contrast-induced nephropathy.

Heme oxygenase-1 counteracts contrast media-induced endothelial cell dysfunction

Endothelial cell (EC) dysfunction is involved in the pathogenesis of contrast-induced acute kidney injury, which is a major adverse event following coronary angiography. In this study, we evaluated the effect of contrast media (CM) on human EC proliferation, migration, and inflammation, and determined if heme oxygenase-1 (HO-1) influences the biological actions of CM. We found that three distinct CM, including high-osmolar (diatrizoate), low-osmolar (iopamidol), and iso-osmolar (iodixanol), stimulated the expression of HO-1 protein and mRNA. The induction of HO-1 was associated with an increase in NF-E2-related factor-2 (Nrf2) activity and reactive oxygen species (ROS). CM also stimulated HO-1 promoter activity and this was prevented by mutating the antioxidant responsive element or by overexpressing dominant-negative Nrf2. In addition, the CM-mediated induction of HO-1 and activation of Nrf2 was abolished by acetylcysteine. Finally, CM inhibited the proliferation and migration of ECs and stimulated the expression of intercellular adhesion molecule-1 and the adhesion of monocytes on ECs. Inhibition or silencing of HO-1 exacerbated the anti-proliferative and inflammatory actions of CM but had no effect on the anti-migratory effect. Thus, induction of HO-1 via the ROS-Nrf2 pathway counteracts the anti-proliferative and inflammatory actions of CM. Therapeutic approaches targeting HO-1 may provide a novel approach in preventing CM-induced endothelial and organ dysfunction.

Prevention of Contrast-Induced Nephropathy (CIN) in Interventional Radiology Practice

Contrast-induced nephropathy (CIN) is a widely recognized and clinically significant problem in patients undergoing an increasing number of minimally invasive procedures that require contrast administration. Contrast-induced nephropathy is the third most common cause of hospital-acquired renal failure and has significant prognostic implications on patient outcomes. Interventional practitioners are faced with challenging decisions regarding prophylaxis and patient management. The major risk factor for developing CIN is preexisting renal dysfunction, particularly in association with diabetes. Patients are considered to be at risk when estimated glomerular filtration rate (eGFR) or estimated creatinine clearance (eC(Cr)) is less than 60. The cornerstone of prevention of CIN is appropriate risk stratification, intravenous hydration with normal saline or sodium bicarbonate, appropriate withholding of nephrotoxic medications, use of low or iso-osmolar contrast media, and various intraprocedural methods for iodinated contrast dose reduction. Although N-acetylcysteine administration is popular, it remains unproven. Practitioners must be familiar with prevention strategies and diagnosis of CIN to minimize its clinical impact.

Clinical pharmacology, uses, and adverse reactions of iodinated contrast agents: a primer for the non-radiologist

Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging modalities. Physicians in almost all specialties will either administer these agents or care for patients who have received these drugs. Different iodinated contrast agents vary greatly in their properties, uses, and toxic effects. Therefore, clinicians should be at least superficially familiar with the clinical pharmacology, administration, risks, and adverse effects associated with iodinated contrast agents. This primer offers the non-radiologist physician the opportunity to gain insight into the use of this class of drugs.

Imaging-related medications: a class overview

Imaging-related medications (contrast agents) are commonly utilized to improve visualization of radiographic, computed tomography (CT), and magnetic resonance (MR) images. While traditional medications are used specifically for their pharmacological actions, the ideal imaging agent provides enhanced contrast with little biological interaction. The radiopaque agents, barium sulfate and iodinated contrast agents, confer "contrast" to x-ray films by their physical ability to directly absorb x-rays. Gadolinium-based MR agents enhance visualization of tissues when exposed to a magnetic field. Ferrous-ferric oxide-based paramagnetic agents provide negative contrast for MR liver studies. This article provides an overview of clinically relevant information for the imaging-related medications commonly in use. It reviews the safety improvements in new generations of drugs; risk factors and precautions for the reduction of severe adverse reactions (i.e., extravasation, contrast-induced nephropathy, metformin-induced lactic acidosis, and nephrogenic fibrosing dermopathy/nephrogenic systemic fibrosis); and the significance of diligent patient screening before contrast exposure and appropriate monitoring after exposure.

Multidetector computed tomography urography for diagnosing upper urinary tract urothelial tumour

OBJECTIVE

To evaluate multidetector computed tomography urography (MDCTU) for diagnosing upper urinary tract (UUT) urothelial tumour by comparison with retrograde ureteropyelography (RUP).

PATIENTS AND METHODS

MDCTU and RUP were used in a selected series of adult patients presenting with haematuria. Entry criteria were based on findings on intravenous urography and were chosen to ensure a high prevalence of UUT urothelial tumour to allow a valid retrospective comparison of the diagnostic techniques. MDCTU and RUP studies were scored for the presence and absence of UUT urothelial tumour by two radiologists, retrospectively and independently, and while unaware of the demographic and clinical information. The reference standards were the histopathology and clinical follow-up.

RESULTS

MDCTU and RUP were used in 106 patients over a 24-month period. RUP was attempted in 151 of 212 UUTs; the corresponding MDCTU for each UUT was reviewed. MDCTU was a true-positive (TP) for urothelial tumour in 31, true-negative (TN) in 111, false-positive (FP) in eight and false-negative (FN) in one UUT, giving a sensitivity of 0.97, a specificity of 0.93, a positive predictive value (PPV) of 0.79 and a negative PV (NPV) of 0.99. RUP was technically successful and diagnostic in 96% of the UUTs (143/151). For diagnosing urothelial tumour, RUP was TP in 26, TN in 112, FP in four and FN in one UUT, giving a sensitivity of 0.97, specificity of 0.93, a PPV of 0.79 and NPV of 0.99.

CONCLUSION

This study validates quantitatively the use of MDCTU for diagnosing UUT urothelial tumour.

Review article: Acute serious and fatal reactions to contrast media: our current understanding

Serious or fatal reactions to a contrast medium (CM) are unpredictable but fortunately rare. History of serious reaction to CM, bronchial asthma or multiple allergies increases the incidence of serious reactions by a factor of 5. Serious or fatal reaction to CM could be due to direct effect on basophils and mast cells or IgE mediated (type 1 hypersensitivity reaction). Activation of the kinin system leading to the formation of bradykinin could also be involved. Complement activation is unlikely to be a primary factor in initiating a serious reaction to CM. Avoiding CM administration in patients at high risk of serious reaction is advisable, but if the administration is deemed essential all precautions should be implemented and measures to treat serious reactions should be readily available. Oxygen supplementation, intravenous administration of physiological fluids and intramuscular injection of 0.5 ml adrenalin (1:1000) should be considered in the first line management of acute anaphylaxis. The ability to assess and treat serious CM reaction effectively is an essential skill that the radiologist should have and maintain.

Effects of radiographic contrast media on pulmonary vascular resistance of normoxic and chronically hypoxic pulmonary hypertensive rats

Intravascular radiographic contrast media (RCM) can be associated with significant morbidity in patients with pulmonary hypertension (PH). This study investigated the direct effect of the four main classes of RCM (high osmolar ionic monomer "diatrizoate"; low osmolar ionic dimer "ioxaglate"; low osmolar non-ionic monomer "iopromide"; and iso-osmolar non-ionic dimer "iotrolan") in ex vivo isolated rat lungs perfused with blood at 20 ml min(-1) under basal conditions (air + 5% CO2 ventilation, pulmonary artery pressure (Ppa) 16-20 mmHg) and when Ppa was raised by hypoxic vasoconstriction in normal rats (2-3% O2+5% CO2 ventilation, Ppa increased by 4-14 mmHg). The effects of low osmolar RCM (ioxaglate, iopromide and iotrolan) were also studied in rats with PH induced by chronic hypoxia (3 weeks 10% O2, Ppa 26-36 mmHg). Increasing volumes (0.05 ml, 0.1 ml, 0.3 ml, and 0.5 ml) of RCM, mannitol (osmolar and pH control) or normal saline (volume control) were added to the 10 ml blood reservoir (n=4-9 per group). In normal rats, RCM caused a dose-dependent slow rise in Ppa. The maximum rise in mean+/-SEM Ppa at the cumulative dose of 0.95 ml was ioxaglate 13.8+/-1.6 mmHg>iotrolan 7.3+/-1.7 mmHg=diatrizoate 9.8+/-2.2 mmHg>iopromide 3.0+/-0.8 mmHg (p<0.05). The rise in Ppa induced by ioxaglate and iotrolan was significantly greater than in the mannitol and saline controls (p<0.05). Pre-treatment with endothelin receptor A/B blockade (SB209670) did not abolish the rise in Ppa induced by diatrizoate (0.95 ml) in the normal rat (3.8+/-1.3 mmHg diatrizoate alone and 3.4+/-1.1 mmHg in the presence of 40 microM SB209670, n=5 per group). When Ppa was raised by acute hypoxia, ioxaglate and diatrizoate (0.5 ml) caused a fall in Ppa (percentage fall -53+/-23 and -118+/-10, respectively, p<0.001) while iotrolan and iopromide caused a small further rise in Ppa, which was significant with iotrolan at a dose of 0.3 ml (percentage rise in pressure 14.2+/-2.3, p<0.05). In chronic pulmonary hypertensive rats, RCM (0.95 ml) caused an overall slow progressive rise in Ppa (iopromide 6.8+/-1.7 mmHg< ioxaglate 11.6+/-2.5 mmHg=iotrolan 12.7+/-1.1 mmHg). However, ioxaglate initially induced an acute fall of Ppa (maximum fall 4.22+/-0.9 mmHg, p<0.05) for almost 20 min. In summary, iopromide induced the least change in Ppa of normal and pulmonary hypertensive rats. The pathophysiology of the effects of RCM on the pulmonary circulation remains uncertain.

Effects of radiographic contrast media on proliferation and apoptosis of human vascular endothelial cells

The aim of the study was to determine the effects of radiographic contrast media (RCM) on proliferation and apoptosis of human vascular endothelial cells. Human umbilical vein endothelial cells (HUVECs) were exposed for either 1 min or 15 min to RCM (diatrizoate, ioxaglate, iopromide, iotrolan) at an iodine concentration of 250 mgl ml-1. Controls were complete growth medium (CGM) and saturated mannitol (osmotic control). [3H]thymidine incorporation was used to determine cell proliferation 24 h after exposure. Apoptosis was determined at 1 h and 6 h by terminal uridine nick end labelling (TUNEL), time lapse video microscopy (TLVM) and DNA electrophoresis. Mean proliferation rates (%) (+/- SEM) (p-values compared with the CGM control) at 1 min and 15 min, respectively, were: diatrizoate: 31.9 (10.6), 5.8 (1.5) (p < 0.001); ioxaglate: 48.4 (10.9), 20.4 (4.5) (p < 0.001); iopromide: 63.4 (8.7), 58.2 (10.2) (p < 0.05); iotrolan: 84.7 (7.3), 72.8 (12.4) (p = ns); saturated mannitol 50.5 (9.6), 45.9 (10.0) (p < 0.001). Mean apoptotic indices (%) (+/- SEM) at 1 h and 6 h following 1 min exposure, respectively, were: CGM: 0.25 (0.13), 0.23 (0.08); diatrizoate: 2.18 (0.19), 2.69 (0.34) (p < 0.001); ioxaglate: 1.90 (0.23), 1.69 (0.02) (p < 0.05); iopromide: 0.59 (0.04), 0.33 (0.02) (p = ns); iotrolan: 0.30 (0.07), 0.27 (0.1) (p = ns); saturated mannitol 2.11 (0.24), 1.4 (0.1) (p < 0.05). After 15 min exposure, apoptosis rates at both 1 h and 6 h, respectively, were: iotrolan: 0.29 (0.17), 0.51 (0.16) (p = ns); diatrizoate: 3.19 (0.81), 11.66 (1.75) (p < 0.001); ioxaglate: 1.88 (0.14), 2.87 (0.20) (p < 0.05); iopromide: 1.06 (0.11), 1.52 (0.15) (p < 0.05); saturated mannitol 1.62 (0.09), 4.63 (0.74) (p < 0.05). TLVM and DNA electrophoresis confirmed the occurence of apoptosis after exposure to RCM. In conclusion, saturated mannitol and all tested RCM, with the exception of iotrolan, (diatrizoate > ioxaglate > iopromide) reduced proliferation and increased apoptosis of HUVECs. The effects were more pronounced with ionic RCM and seem to depend on osmolality as well as the chemical structure of these agents. Endothelial injury and apoptosis may be responsible for some of the side effects associated with intravascular use of RCM.