Evaluation of the clinical safety of gadodiamide injection, a new nonionic MRI contrast medium for the central nervous system: a European perspective

Investigating the Role of Sulfate Groups for the Binding of Gd3+ Ions to Glycosaminoglycans with NMR Relaxometry

Glycosaminoglycans (GAGs) are highly negatively charged macromolecules with a large cation binding capacity, but their interaction potential with exogeneous Gd³⁺ ions is under‐investigated. These might be released from chelates used as Gadolinium‐based contrast agents (GBCAs) for clinical MR imaging due to transmetallation with endogenous cations like Zn²⁺. Recent studies have quantified how an endogenous GAG sequesters released Gd³⁺ ions and impacts the thermodynamic and kinetic stability of some GBCAs. In this study, we investigate and compare the chelation ability of two important GAGs (heparin and chondroitin sulfate), as well as the homopolysaccharides dextran and dextran sulfate that are used as models for alternative macromolecular chelators. Our combined approach of MRI‐based relaxometry and isothermal titration calorimetry shows that the chelation process of Gd³⁺ into GAGs is not just a long‐range electrostatic interaction as proposed for the Manning model, but presumably a site‐specific binding. Furthermore, our results highlight the crucial role of sulfate groups in this process and indicate that the potential of a specific GAG to engage in this mechanism increases with its degree of sulfation. The transchelation of Gd³⁺ ions from GBCAs to sulfated GAGs should thus be considered as one possible explanation for the observed long‐term deposition of Gd³⁺in vivo and related observations of long‐term signal enhancements on T₁‐weighted MR images.

An NMR relaxometry approach for quantitative investigation of the transchelation of gadolinium ions from GBCAs to a competing macromolecular chelator

Gadolinium-based contrast agents (GBCAs) have been used in clinical Magnetic Resonance Imaging (MRI) for more than 30 years. However, there is increasing evidence that their dissociation in vivo leads to long-term depositions of gadolinium ions in the human body. In vitro experiments provide critical insights into kinetics and thermodynamic equilibria of underlying processes, which give hints towards the in vivo situation. We developed a time-resolved MRI relaxometry-based approach that exploits distinct relaxivities of Gd3+ in different molecular environments. Its applicability to quantify the transmetallation of GBCAs, the binding of Gd3+ to competing chelators, and the combined transchelation process is demonstrated. Exemplarily, the approach is applied to investigate two representative GBCAs in the presence of Zn2+ and heparin, which is used as a model for a macromolecular and physiologically occurring chelator. Opposing indirect impacts of heparin on increasing the kinetic stability but reducing the thermodynamic stability of GBCAs are observed. The relaxivity of resulting Gd-heparin complexes is shown to be essentially increased compared to that of the parent GBCAs so that they might be one explanation for observed long-term MRI signal enhancement in vivo. In forthcoming studies, the presented method could help to identify the most potent Gd-complexing macromolecular species.

A Structured Survey on Adverse Events Occurring Within 24 Hours After Intravenous Exposure to Gadodiamide or Gadoterate Meglumine: A Controlled Prospective Comparison Study

OBJECTIVE

This study compares the incidence of new-onset symptoms within 24 hours after enhanced magnetic resonance imaging (eMRI) with intravenous administration of gadodiamide or gadoterate meglumine compared with a control group undergoing unenhanced MRI (uMRI).

MATERIALS AND METHODS

A prospective cohort study (n = 1088 patients) was designed to assess the incidence of symptoms within 24 hours after administration of gadodiamide or gadoterate meglumine. The participants underwent a structured questionnaire by phone call before and 24 hours after the MRI scan to check for symptoms that were not present before the scan. The questionnaire included a list of active questions aimed to test the prevalence of symptoms that have been proposed in the debated definition of gadolinium deposition disease (GDD) and that we recorded in this study as GDD-like. In particular, the following symptoms and signs were tested: central torso pain, arm or leg pain, bone pain, headache, skin redness (any site of the body), fatigue, and mental confusion.Fisher exact test was used to test differences between groups with significance threshold set at P < 0.05.

RESULTS

Within the 24 hours after the MRI scan, 8.3% of patients reported at least one new-onset symptom in the uMRI group versus 17.4% in the gadodiamide eMRI versus 17.8% in the gadoterate meglumine eMRI group. The difference between the eMRI and the uMRI group was statistically significant (P < 0.001 for gadodiamide and P < 0.001 for gadoterate meglumine). There was not a different incidence of symptoms between the gadodiamide and the gadoterate meglumine eMRI groups. For gadodiamide, fatigue (P < 0.05) and dizziness (P < 0.05) were symptoms significantly more frequent than uMRI group; for gadoterate meglumine, fatigue (P < 0.01), mental confusion (P < 0.01), and diarrhea (P < 0.01) were significantly more frequent than uMRI group.

CONCLUSIONS

We found that the onset of new symptoms within 24 hours after exposure to gadolinium-based contrast agent was more frequent than after uMRI. Among GDD-like symptoms, fatigue and mental confusion were the most frequent symptoms reported after eMRI. The other GDD-like symptoms were not overreported after eMRI versus uMRI. Thus, these results are questioning the term GDD.

Influence of excess ligand on Nephrogenic Systemic Fibrosis associated with nonionic, linear gadolinium-based contrast agents

BACKGROUND

The molecular structure, charge, thermodynamic and kinetic stability are approximately the same for gadodiamide and gadoversetamide, the main substantive difference is that gadodiamide is manufactured with 5% free ligand to form Omniscan® and gadoversetamide with 10% free ligand to form OptiMARK®.

PURPOSE

To determine the relative risk of Nephrogenic Systemic Fibrosis (NSF) between gadodiamide (Omniscan®) and gadoversetamide (OptiMARK®) and to explore the potential contribution of the amount of excess ligand added to their commercial formulations.

MATERIALS AND METHODS

In this retrospective observational study, the number of doses and NSF cases associated with these agents were calculated based on two different approaches: the number of doses was determined based on pharmaceutical companies' information, and the number of unconfounded NSF cases was obtained from the previously published literature based on a legal database. A second analysis estimates the number of doses and NSF cases from the Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS).

RESULTS

Approximately 87 million and 12 million doses of Omniscan® and OptiMARK®, respectively, have been administered worldwide since their original approval for use in the various countries throughout the world. A total of 197 and 8 unconfounded cases of NSF have been reported with Omniscan® and OptiMARK®, rendering an incidence of 2.3/million and 0.7/million for these agents, respectively. The FAERS analysis suggested reported incidences of 13.1/million and 5.0/million.

CONCLUSION

There is an approximately 3-fold greater incidence of NSF from Omniscan® than OptiMARK®. The difference in incidence might reflect the lesser quantity of added free ligand to the formulation of Omniscan®.

The Impact of Excess Ligand on the Retention of Nonionic, Linear Gadolinium-Based Contrast Agents in Patients With Various Levels of Renal Dysfunction: A Review and Simulation Analysis

The role of gadolinium (Gd)-based contrast agents (GBCAs) in the pathophysiology of nephrogenic systemic fibrosis (NSF) is now uncontested. Although the definitive mechanism has not been established, the association with weaker GBCA ligands and with reduced renal clearance supports a hypothesis that Gd release from the GBCAs is a key process in precipitating the disease. Prevention strategies often include the use of more stable GBCA ligands in patients with reduced kidney function, but animal models and some clinical data suggest that better patient outcomes can be achieved when excess ligand is administered with weaker GBCAs; this is particularly significant for OptiMARK, which contains a nonionic, linear ligand similar to gadodiamide, the active ingredient in Omniscan, but contains twice the amount of excess ligand. Here we review evidence regarding the use of OptiMARK over Omniscan for prevention of NSF and perform a pharmacokinetic-based simulation to determine if the presented evidence is consistent with the established kinetics of GBCAs and Gd.

Gadolinium-containing magnetic resonance contrast media: investigation on the possible transchelation of Gd³⁺ to the glycosaminoglycan heparin

Retention of gadolinium (Gd) in biological tissues is considered an important cofactor in the development of nephrogenic systemic fibrosis (NSF). Research on this issue has so far focused on the stability of Gd-based contrast media (GdCM) and a possible release of Gd³⁺ from the complex. No studies have investigated competing chelators that may occur in vivo. We performed proton T(1) -relaxometry in solutions of nine approved GdCM and the macromolecular chelator heparin (250 000 IU per 10 ml) without and with addition of ZnCl₂. For the three linear, nonspecific GdCM complexes, Omniscan®, OptiMARK® and Magnevist®, 2 h of incubation in heparin at 37 °C in the presence of 2.0 mm ZnCl₂ led to an increase in T₁-relaxivity by a factor of 7.7, 5.6 and 5.1, respectively. For the three macrocyclic complexes, Gadovist®, Dotarem® and Prohance®, only a minor increase in T₁-relaxivity by a factor of 1.5, 1.6 and 1.7 was found, respectively. Without addition of ZnCl₂, no difference between the two GdCM groups was observed (factors of 1.4, 1.2, 1.1, 1.3, 1.5 and 1.4, respectively). The increase in T₁-relaxivities observed for linear GdCM complexes may be attributable to partial transchelation with formation of a macromolecular Gd-heparin complex. For comparison, mixing of GdCl₃ and heparin results in a 8.7-fold higher T₁-relaxivity compared with a solution of GdCl₃ in water. Heparin is a glycosaminoglycan (GAG) and as such occurs in the human body as a component of the extracellular matrix. GAGs generally are known to be strong chelators. Gd³⁺ released from chelates of GdCM might be complexed by GAGs in vivo, which would explain their retention in biological tissues. Plasma GAG levels are elevated in end-stage renal disease; hence, our results might contribute to the elucidation of NSF.

Extracellular gadolinium-based contrast media: differences in diagnostic efficacy

Since the introduction of the first gadolinium-based contrast agent (Gd-CA) in 1988 it has become clear that these agents significantly improve the diagnostic efficacy of MRI. Studies on single agents have shown that, in comparison to unenhanced sequences, all agents help to improve the detection and delineation of lesions which can alter diagnosis in up to 40% of patients. Doubling or tripling the standard dose of 0.1 mmol/kg body weight may be beneficial for selected indications (e.g. brain perfusion, equivocal single dose study in MRI for brain metastasis, small vessel MR angiography). A more limited number of studies have compared the various agents. These studies do not show clinically significant differences in diagnostic efficacy between the various extracellular Gd-CA. Agents with higher concentration or protein binding may be relatively better suitable for selected applications (e.g. perfusion MRI). The higher relaxivity agents may be used in somewhat lower doses than the extracellular agents.

Abdominal and iliac arterial stenoses: comparative double-blinded randomized study of diagnostic accuracy of 3D MR angiography with gadodiamide or gadopentetate dimeglumine

PURPOSE

To prospectively evaluate accuracy of gadolinium-enhanced three-dimensional (3D) magnetic resonance (MR) angiography with gadodiamide and gadopentetate dimeglumine (0.1 mmol/kg), with intraarterial DSA as reference standard, for imaging abdominal and iliac arterial stenoses.

MATERIALS AND METHODS

The study was approved by all institutional review boards; informed consent was obtained from each subject before procedures. Two hundred forty-seven subjects were included; 240 received either contrast agent and were available for safety analysis; 222 were available for accuracy analysis. Enhanced 3D MR angiography and DSA were performed; image data were evaluated in a double-blinded randomized study. Stenoses were classified as not relevant (<50% stenosis) or relevant (> or =50%). For detection of main stenosis, accuracy with enhanced 3D MR angiography compared with that with DSA was determined.

RESULTS

The difference in accuracy for imaging with gadodiamide and gadopentetate was 3.6%. Noninferiority was inferred because the lower bound of the exact two-sided 95% confidence interval was -10.1 and was above the noninferiority margin (-15%). Accuracy for detection of the main stenosis was low, 56.4% for gadodiamide and 52.8% for gadopentetate group. Subgroup analysis with exclusion of inferior mesenteric artery and internal iliac arteries and the most false-positive stenosis classifications yielded better results: 76.6% and 71.6%, respectively. Sensitivity, specificity, and negative and positive predictive values did not differ substantially between study groups. In the main analysis, values were 44%, 96%, 35%, and 97% for gadodiamide and 44%, 83%, 30%, and 90% for gadopentetate, respectively. In the subgroup analysis, values were 66%, 95%, 61%, and 96% for gadodiamide and 63%, 86%, 58%, and 88% for gadopentetate, respectively.

CONCLUSION

Noninferiority of gadodiamide versus gadopentetate was verified based on the primary end point, which was accuracy for detection of the main stenosis with enhanced 3D MR angiography compared with DSA.

Efficacy and safety of MR imaging with liver-specific contrast agent: U.S. multicenter phase III study

PURPOSE

To assess prospectively the efficacy and safety of postcontrast magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) compared with that of precontrast MR imaging in patients who are known to have or are suspected of having liver lesions and who are scheduled for hepatic surgery.

MATERIALS AND METHODS

Investigational review board approval and written informed consent were obtained. HIPAA went into effect after data collection. A total of 172 patients were enrolled. After precontrast MR imaging, 169 patients (94 men, 75 women; mean age, 61 years; age range, 19-84 years) received an intravenous bolus of 25 micromol/kg Gd-EOB-DTPA and underwent dynamic gradient-recalled-echo and delayed MR imaging 20 minutes after injection. Arterial and portal phase computed tomography (CT) were performed within 6 weeks of MR imaging. The standard of reference was surgery with intraoperative ultrasonography (US) and biopsy and/or pathologic evaluation of resected liver segments and/or 3-month follow-up of nonresected segments if intraoperative US was not available. Three blinded reviewers and unblinded site investigators identified liver lesions on segment maps. The Wilcoxon signed rank test was used to compare differences in per-patient sensitivity of precontrast and postcontrast MR images. Adverse events were recorded, and patient monitoring and laboratory assay were performed at time of injection and up to 24 hours after contrast material administration.

RESULTS

At MR imaging, 316 lesions were identified in 131 patients. In 77% (P = .012), 72% (P = .15), and 71% (P = .027) of patients for readers 1, 2, and 3, respectively, more lesions were seen at precontrast and postcontrast MR imaging combined than at precontrast MR imaging alone. Sensitivity values for blinded readings were significantly greater at postcontrast MR imaging than at precontrast MR imaging for two of three blinded readers. For all blinded readers, combined precontrast and postcontrast MR images showed no difference in sensitivity compared with helical CT scans. The use of MR imaging, however, yielded fewer patients with at least one false-positive lesion (37%, 31%, and 34% of patients for readers 1, 2, and 3, respectively) than did helical CT (45%, 36%, and 43% of patients for readers 1, 2, and 3, respectively).

CONCLUSION

Compared with precontrast MR imaging, postcontrast MR imaging with Gd-EOB-DTPA demonstrated improved sensitivity for lesion detection in the majority of blinded readers, with no substantial adverse events.

Contrast agents for magnetic resonance imaging: safety update

Magnetic resonance contrast agents, particularly the gadolinium-based agents, are extremely safe and lack the nephrotoxicity associated with iodinated contrast media. Currently, seven gadolinium agents are available in one or more countries of the world, of which only four are available for clinical use in the United States. Minor adverse effects associated with each of these agents occur infrequently and include nausea, headache, and taste perversion. Whereas the gadolinium agents cannot be differentiated on the basis of these mild adverse effects, recent studies have brought to light the issue of chelate stability, and in particular, clinical observations associated with the least stable of these agents. This review briefly discusses the most recent safety issues concerning the gadolinium agents. A brief review of safety issues concerning the non-gadolinium agents is also provided.

Gadobenate dimeglumine-enhanced magnetic resonance imaging of intracranial metastases: effect of dose on lesion detection and delineation

Seventy-four patients with one to eight proven intraaxial metastatic lesions to the brain received a total gadobenate dimeglumine dose of 0.3 mmol/kg of body weight, administered as three sequential bolus injections of 0.1 mmol/kg, at 10-minute intervals over a 20-minute period. Quantitative and qualitative assessments of efficacy were performed after each injection and a full evaluation of safety was conducted. Cumulative dosing produced significant (P < 0.01) dose-related increases in lesion-to-brain (L/B) ratio and lesion signal intensity (SI) enhancement. Two independent, blinded assessors noted additional lesions, compared to unenhanced images in 31% and 33%, 49% and 42%, and 50% and 48% of patients after each cumulative dose, respectively. Significantly more lesions were noted after the first injection, compared to unenhanced images (P = 0.002 and P < 0.001; assessors 1 and 2, respectively), and after a second injection, compared to the first (P < 0.001 and P = 0.039; assessors 1 and 2, respectively). Neither assessor noted significantly more lesions after the third injection. For patients with just one lesion observed on unenhanced T1- and T2-weighted images, additional lesions were noted by assessors 1 and 2 for 27% and 26%, 48% and 35%, and 42% and 41% of patients, respectively, following each injection. Contemporaneously, diagnostic confidence was increased and lesion conspicuity improved over unenhanced magnetic resonance imaging (MRI). For patients with one lesion observed after 0.1 mmol/kg of gadobenate dimeglumine, additional lesions were noted for 24% and 17% of patients (assessors 1 and 2, respectively) following a second 0.1 mmol/kg injection. Only assessor 2 noted additional lesions following the third 0.1 mmol/kg injection. The findings of on-site investigators concurred with those of the two off-site assessors. No safety concerns were apparent.

Safety assessment of gadobenate dimeglumine (MultiHance): extended clinical experience from phase I studies to post-marketing surveillance

Clinical trials completed by September 2000 on gadobenate dimeglumine (Gd-BOPTA; MultiHance) included 2540 adult and pediatric subjects that were administered this agent. For adult patient volunteers, the overall incidence of adverse events (AEs) was 19.8%, although marked study- and indication-related differences were apparent. Events potentially related to Gd-BOPTA administration were reported for 15.1% of adult patients. The vast majority of AEs were non-serious, mild, transient, and self-resolving. Headache, injection site reaction, nausea, taste perversion, and vasodilation were the most common AEs, reported with a frequency of between 1.0% and 2.6%. Serious AEs potentially related to Gd-BOPTA were reported for five (0.2%) patients overall. Controlled studies revealed no differences between Gd-BOPTA and other gadolinium chelates or placebo in the incidence and type of AEs. Similarly, no differences with respect to adult patients and/or comparator were noted in studies on pediatric subjects and subjects with renal or liver insufficiency. Post-marketing surveillance of approximately 100000 doses revealed an overall AE incidence of < 0.03% with serious AEs reported for < 0.005% of patients.

Safety and efficacy of Omniscan (gadodiamide injection) at 0.1 mmol/kg for MRI in infants younger than 6 months of age: phase III open multicenter study

RATIONALE AND OBJECTIVES

To demonstrate that gadodiamide injection is a safe and efficient contrast agent for MRI in infants younger than 6 months of age.

METHODS

The authors designed a phase III multicenter nonrandomized study using a control group. Gadodiamide injection at a dosage of 0.1 mmol/kg body weight was administered to 39 children; 20 received no contrast. The mean age was 10.6 weeks in the contrast group and 9.3 weeks in the control group. MR examinations, blood (serum creatinine, S-ASAT, S-ALAT, S-bilirubin, alkaline phosphatase) and urine (proteins, blood, others) sampling before sedation and after examination, heart rate (electrocardiography) and oxygen saturation (pulse oximetry) during examination, adverse events, and efficacy parameters were analyzed.

RESULTS

In the contrast group, 18 (51.4%) children had 31 abnormal changes in one or more of the safety parameters and vital signs. In the control group there were 16 (80.0%) children with 19 abnormal changes. Gadodiamide injection had no negative influence on the safety parameters. No serious adverse events occurred, and only three clinically relevant adverse events (elevation of S-ALAT and S-ASAT, elevation of bilirubin) in two patients in the contrast group and one event (vomiting) in one patient in the control group were documented. The benefit of the contrast medium was clearly shown for all evaluated parameters.

CONCLUSIONS

Gadodiamide injection is safe, well tolerated, and effective in infants younger than 6 months of age.

Occurrence of adverse reactions to gadolinium-based contrast material and management of patients at increased risk: a survey of the American Society of Neuroradiology Fellowship Directors

RATIONALE AND OBJECTIVES

The authors attempted to determine the frequency and severity of adverse reactions to gadolinium-based magnetic resonance (MR) contrast agents and to identify strategies for management of patients at increased risk.

MATERIALS AND METHODS

American Society of Neuroradiology program directors were surveyed about adverse reactions at their institutions to gadolinium-based contrast agents, the contrast agents responsible, and the management of patients with allergy-like reactions to iodinated or gadolinium-based agents who required MR contrast agent administration.

RESULTS

Fifty-three (50.5%) surveys were received from 105 centers. Of 687,255 gadopentetate dimeglumine injections, 314 (0.046%) nonallergic reactions and 107 (0.016%) mild, 28 (0.004%) moderate, and five (0.001%) severe allergy-like reactions occurred. Of 74,275 gadodiamide injections, 11 (0.015%) nonallergic and 12 (0.016%) mild allergy-like reactions occurred. Of 64,005 gadoteridol administrations, 171 (0.267%) nonallergic reactions and 49 (0.077%) mild, 29 (0.047%) moderate, and 11 (0.017%) severe allergy-like reactions occurred. Twenty-six departments took no precautions for patients with previous allergy-like reactions to iodinated contrast material. Nineteen did not premedicate patients who previously had reactions to gadolinium-based agents before repeat administration of MR contrast agents.

CONCLUSION

Although MR contrast agents are safe, adverse reactions occur. Many centers have not adopted policies for the OFF

Synthesis and Physicochemical Characterization of a New Gadolinium Chelate: The Liver-Specific Magnetic Resonance Imaging Contrast Agent Gd-EOB-DTPA

A convenient synthesis of disodium S-[4-(4-ethoxybenzyl)-3,6,9-tris[(carboxy-kappaO)methyl]-3,6,9-triazaundecandioato)(5-)-kappa(3)N(3)(),N(6)(),N(9)(),kappa(2)O(1)(),O(11)()]gadolinate(2-) (Gd-EOB-DTPA), 1, is reported. This water-soluble complex is presently undergoing phase III clinical trials as a liver-specific contrast agent for magnetic resonance imaging (MRI). The thermodynamic complex stability constant of 1 and the acid dissociation constants of the ligand have been determined as well as the stability constant of the calcium complex Ca-EOB-DTPA (2), which is used as an additive in the pharmaceutical formulation of the contrast agent. The solid-state structure of the ligand S-4-(4-ethoxybenzyl)-3,6,9-tris(carboxylatomethyl)-3,6,9-triazaundecanedioic acid (H(5)EOB-DTPA), 3, has been elucidated in a single crystal X-ray diffraction study. Additionally, HPLC evidence is given that the enantiomerically pure ligand forms two diastereomeric gadolinium complexes in a 65:35 ratio. The kinetics of isomerization of the isolated diastereomers-as dependent on pH and temperature-has been investigated, and thus, the activation energy for the interconversion of these isomers has been estimated to be 75.3 kJ mol(-1). Finally, the structures of the two components of 1 are discussed in terms of four possible diastereomers.