Pharmacokinetics, safety, and tolerability of gadoversetamide injection (OptiMARK) in subjects with central nervous system or liver pathology and varying degrees of renal function

[ESUR recommendations on the use of contrast media: Practice survey, review and commentary by CJN, FIRN and SFNDT]

Contrast media administration is classically considered to cause or worsen kidney failure. Recent data may moderate this assertion. The European Society of Urogenital Radiology recently published guidelines re-evaluating the precautions before administering contrast media. The present work evaluates the practice of French nephrologists, and provides a commentary on these recommendations based on an updated review of the literature. We conducted survey among French nephrologists, using an electronic questionnaire distributed by the Société Francophone de Néphrologie, Dialyse et Transplantation, the French Intensive care Renal Network and the Club des Jeunes Néphrologues. 266 responses were collected. The European Society of Urogenital Radiology guidelines are poorly known among the panel of nephrologists. Their practices differ from the guidelines by the more frequent and earlier implementation of measures to prevent renal failure post contrast media. In accordance with the guidelines, hydration is prescribed as a first-line preventive measure, mainly with saline and bicarbonate. Inhibitors of the renin-angiotensin-aldosterone system are frequently discontinued before an injection of contrast media, contrary to what is recommended. In conclusion, the European Society of Urogenital Radiology guidelines, which the working group endorses, but which are still too little known and applied in clinical nephrology in France, prompt nephrologists to lift some of the restrictions on the use of PCI as well as on the continuation of ARS inhibitors before injecting PCI.

Kidney and contrast media: Common viewpoint of the French Nephrology societies (SFNDT, FIRN, CJN) and the French Radiological Society (SFR) following ESUR guidelines

Contrast medium administration is classically considered to cause or worsen kidney failure, but recent data may moderate this assertion. The European Society of Urogenital Radiology recently published guidelines re-evaluating the precautions before administering contrast media. Kidney injury does not constitute a contra-indication to the administration of iodinated contrast medium, as long as the benefit-risk ratio justifies it. Intravenous hydration with 0.9% NaCl or 1.4% sodium bicarbonate is the only validated measure for the prevention of post-iodine contrast nephropathy. This is necessary for intravenous or intra-arterial administration of iodinated contrast agent without first renal pass when the glomerular filtration rate is less than 30mL/min/1.73m², for intra-arterial administration of iodinated contrast agent with first renal passage when the glomerular filtration rate is less than 45mL/min/1.73m², or in patients with acute renal failure. The use of iodinated contrast medium should allow the carrying out of relevant examinations based on an analysis of the benefit-risk ratio and the implementation of measures to prevent toxicity when necessary.

Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers

Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compounds, and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathological changes in the local environment. This comprehensive review describes the state of the art of clinically approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chemical exchange saturation transfer, and direct detection and the types of molecules that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathology either by direct biochemical targeting or by the design of responsive or activatable contrast agents.

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®.

[Non-iodinated contrast media nephrotoxicity]

The development of interventional radiology techniques regularly exposes patients to the potential renal toxocity of iodinated contrast media. Faced with this risk of nephrotoxicity, gadolinium-based contrast agents have long been considered as a safe alternative to iodinated contrast media, especially in sensitive or at risk patients. However, these gadolinium-based contrast agents are not devoid of nephrotoxicity and present another risk, a complication related to renal failure, the nephrogenic systemic fibrosis. European and US recommendations from health agencies have recently come closer, defining groups of patients at risk of nephrogenic systemic fibrosis according to their level of renal function and the type of gadolinium-based contrast agent used. What are the real renal risks for these products? How to evaluate the benefit-risk balance of the patient to choose a radiological examination in an informative, effective and safe way? This article focuses on the description of the risks of gadolinium-based contrast agents, reviews existing recommendations and best practices to guide the choice of clinicians.

Historical Perspective of Imaging Contrast Agents

Contrast agents were introduced early in the history of medical imaging. Iodine-based intravascular agents became the radiographic compounds of choice and refinements of their chemical structures led to the highly tolerated low-osmolarity agents in use today. Gadolinium became the most popular compound for MR imaging; however, recognition of nephrogenic systemic fibrosis and in vivo dechelation intensified research on their safety profile. Ultrasonography contrast media evolved from manual injections of air through agitated saline solutions to microbubbles with different gases. Research has concentrated on bubble stabilization and development of small but sufficiently echogenic particles.

Gadolinium-based contrast agents in pediatric magnetic resonance imaging

Gadolinium-based contrast agents can increase the accuracy and expediency of an MRI examination. However the benefits of a contrast-enhanced scan must be carefully weighed against the well-documented risks associated with administration of exogenous contrast media. The purpose of this review is to discuss commercially available gadolinium-based contrast agents (GBCAs) in the context of pediatric radiology. We discuss the chemistry, regulatory status, safety and clinical applications, with particular emphasis on imaging of the blood vessels, heart, hepatobiliary tree and central nervous system. We also discuss non-GBCA MRI contrast agents that are less frequently used or not commercially available.

In silico evaluation of gadofosveset pharmacokinetics in different population groups using the Simcyp® simulator platform

Purpose

Gadofosveset is a Gd-based contrast agent used for magnetic resonance imaging (MRI). Gadolinium kinetic distribution models are implemented in T1-weighted dynamic contrast-enhanced perfusion MRI for characterization of lesion sites in the body. Physiology changes in a disease state potentially can influence the pharmacokinetics of drugs and to this respect modify the distribution properties of contrast agents. This work focuses on the in silico modelling of pharmacokinetic properties of gadofosveset in different population groups through the application of physiologically-based pharmacokinetic models (PBPK) embedded in Simcyp® population pharmacokinetics platform.

Methods

Physicochemical and pharmacokinetic properties of gadofosveset were introduced into Simcyp® simulator platform and a min-PBPK model was applied. In silico clinical trials were generated simulating the administration of the recommended dose for the contrast agent (i.v., 30 mg/kg) in population cohorts of healthy volunteers, obese, renal and liver impairment, and in a generated virtual oncology population. Results were evaluated regarding basic pharmacokinetic parameters of Cmax, AUC and systemic CL and differences were assessed through ANOVA and estimation of ratio of geometric mean between healthy volunteers and the other population groups.

Results

Simcyp® predicted a mean Cmax = 551.60 mg/l, a mean AUC = 4079.12 mg/L*h and a mean systemic CL = 0.56 L/h for the virtual population of healthy volunteers. Obese population showed a modulation in Cmax and CL, attributed to increased administered dose. In renal and liver impairment cohorts a significant modulation in Cmax, AUC and CL of gadofosveset is predicted. Oncology population exhibited statistical significant differences regarding AUC when compared with healthy volunteers.

Conclusions

This work employed Simcyp® population pharmacokinetics platform in order to compute gadofosveset’s pharmacokinetic profiles through PBPK models and in silico clinical trials and evaluate possible differences between population groups. The approach showed promising results that could provide new insights regarding administration of contrast agents in special population cohorts. In silico pharmacokinetics could further be used for evaluating of possible toxicity, interpretation of MRI PK image maps and development of novel contrast agents.

Pharmacokinetics of gadobenate dimeglumine in children 2 to 5 years of age undergoing MRI of the central nervous system

PURPOSE

To determine the pharmacokinetic profile of gadobenate dimeglumine in children aged between 2 and 5 years.

MATERIALS AND METHODS

Fifteen children scheduled to undergo contrast-enhanced MRI for suspected disease of the central nervous system received a single intravenous injection of 0.1 mmol/kg gadobenate dimeglumine. Children were stratified into three age groups: 2 to <3 years, 3 to <4 years, and 4 to 5 (i.e., <6 years). Serial blood and urine samples collected at prespecified time-points before and after contrast administration were analyzed for gadolinium concentrations. Pharmacokinetic parameters were calculated using noncompartmental and compartmental techniques.

RESULTS

Mean values of 65.7 μg/mL for highest blood gadolinium concentration, 0.2 L/h/kg for blood clearance, 0.32 L/kg for steady-state volume of distribution, and 1.2 h for terminal elimination half-life were determined across all age groups combined. On average, more than 80% of the dose was eliminated in the urine during the first 24 h after administration. All pharmacokinetic parameters were similar between age groups and no effects of gender were noted. No adverse events considered related to gadobenate dimeglumine administration were reported.

CONCLUSION

In terms of pharmacokinetic profile no dosage adjustment from the approved adult gadobenate dimeglumine dose of 0.1 mmol/kg bodyweight is necessary in children aged between 2 and 5 years.

Safety and adverse effects during 24 hours after contrast-enhanced MRI with gadobenate dimeglumine (MultiHance) in children

BACKGROUND

Gadolinium-based MR contrast agents have long been considered safe for routine diagnostic imaging. However, the advent of nephrogenic systemic fibrosis (NSF) among certain patients with severe renal insufficiency has brought the issue of safety into question. Nowhere is safety of greater concern than among children who frequently require multiple contrast-enhanced MRI examinations over an extended period of time.

OBJECTIVE

To retrospectively evaluate the safety of gadobenate dimeglumine for contrast-enhanced (CE) MRI across a range of indications.

MATERIALS AND METHODS

Two hundred pediatric inpatients (age: 4 days to 15 years) underwent CE MRI as part of clinical routine. The children received a gadobenate dimeglumine dose of either 0.05 mmol/kg body weight (liver, abdominal imaging, musculoskeletal imaging, brain and other rare indications) or 0.1 mmol/kg bodyweight (cardiovascular imaging, MR-urography). Young (< 8 years) children with congenital heart disease were intubated and underwent MRA evaluation with controlled ventilation. Monitoring for adverse events was performed for at least 24 h after each gadobenate dimeglumine injection. Depending on clinical necessity, laboratory measurements and, in some cases, vital sign and ECG determinations were made before and after contrast injection. Safety was evaluated by age group, indication and dose administered.

RESULTS

No clinically adverse events were reported among children who had one MRI scan only or among children who had several examinations. There were no changes in creatinine or bilirubin levels even in very young children.

CONCLUSIONS

No adverse events were recorded during the first 24 h following administration of gadobenate dimeglumine in 200 children.

Nephrogenic systemic fibrosis and gadolinium-based contrast agents

The strong association between nephrogenic systemic fibrosis (NSF) and exposure to gadolinium-based contrast agents (GBCAs) has greatly affected the care of patients with kidney disease. NSF has been reported in patients with ESRD, CKD, and acute kidney injury (AKI). The majority of cases have occurred in patients with ESRD, but about 20% have been reported in patients with AKI or CKD stages 4 and 5. There is also a risk difference among GBCAs, with the Food and Drug Administration contraindicating 3 linear agents in patients at risk. Given the significant morbidity and mortality of NSF, it is imperative to identify individuals at risk. Although there are no data to support a role for hemodialysis (HD) in reducing the risk for NSF after administration of GBCAs, immediate HD is still recommended within 2 hours. Patients maintained on peritoneal dialysis seem to be at high risk and immediate HD is also recommended. However, this is not the current recommendation for CKD stages 4 and 5, especially with suspected lower risk of noncontraindicated agents. Individualized assessment is important and especially in those patients close to dialysis initiation. Instituting policies is important to address the imaging needs of patients with CKD and AKI while ensuring a balance between benefits and risks.

Biodistribution of gadolinium-based contrast agents, including gadolinium deposition

The biodistribution of approved gadolinium (Gd)-based contrast agents (GBCAs) is reviewed. After intravenous injection GBCAs distribute in the blood and the extracellular space and transiently through the excretory organs. Preclinical animal studies and the available clinical literature indicate that all these compounds are excreted intact. Elimination tends to be rapid and, for the most part, complete. In renally insufficient patients the plasma elimination half-life increases substantially from hours to days depending on renal function. In patients with impaired renal function and nephrogenic systemic fibrosis (NSF), the agents gadodiamide, gadoversetamide, and gadopentetate dimeglumine have been shown to result in Gd deposition in the skin and internal organs. In these cases, it is likely that the Gd is no longer present as the GBCA, but this has still not been definitively shown. In preclinical models very small amounts of Gd are retained in the bone and liver, and the amount retained correlates with the kinetic and thermodynamic stability of the GBCA with respect to Gd release in vitro. The pattern of residual Gd deposition in NSF subjects may be different than that observed in preclinical rodent models. GBCAs are designed to be used via intravenous administration. Altering the route of administration and/or the formulation of the GBCA can dramatically alter the biodistribution of the GBCA and can increase the likelihood of Gd deposition. J. Magn. Reson. Imaging 2009;30:1259-1267. (c) 2009 Wiley-Liss, Inc.

[Gadolinium-enhanced thoracic CTA: retrospective analysis of image quality and tolerability in 45 patients evaluated prior to the description of nephrogenic systemic fibrosis]

PURPOSE

To assess the accuracy and torerability of gadolinium-enhanced thoracic CTA using a 64 MDCT compared to a 16 MDCT. Because this study was started prior to the description of NSF, particular attention was paid to long-term follow-up of the patient population.

MATERIALS AND METHODS

The study protocol was approved by the ethics committee of our institution and informed consent was obtained from all patients. Fourteen patients (Group 1) (9 males and 5 females; mean age: 64.3 years) with contraindication to the administration of iodinated contrast material underwent thoracic CTA (collimation: 32 x 2 x 0.6 mm; pitch: 1.2) with gadolinium administration (0.5 mml/ml) at 0.4 mmol/kg injected at 6 ml/sec with evaluation of clinical and biological tolerability of the gadolinium based contrast agent. Results from this patient population were compared to results from a population of 31 patients (21 males; 10 females; mean age: 63.2 years) (Group 2) imaged on a 16 MDCT. All patients were folloowed-up for a mean time of 22.6 months.

RESULTS

Using a mean contrast volume (standard deviation) that was not significantly different (Group 1: 54.8+/-11 ml; Group 2: 53.4+/-6.9 ml) (p=0.94), patients in Group 1 underwent complete thoracic CTA whereas patients in Group 2 underwent CTA of only the middle third of the thoracic region. All CTA examinations were diagnostic for Group 1 and Group 2 patients; however, evaluation of subsegmental vessels was possible in a significantly larger proportion of patients in Group 1 (10/14; 72%) compared to Group 2 (6/31; 19%) (p=0.003). Mean attenuation values within pulmonary arterial branches were similar for Groups 1 and 2 (central arteries: 194.5+/-51.3 HU vs 180.6+/-53.8 HU; p=0.38) (lobar arteries: 208.5+/-52.5 HU vs 189.9+/-60.1 HU; p=0.33) (segmental arteries: 220.4+/-50.4 HU vs 201.5+/-54.7 HU; p=0.42). Transient alteration of renal function was recorded in one patient from Group 1 with severe pre-existing chronic renal failure. No change in renal function was observed for Group 2 patients. No case of NSF was reported in patients with pre-existing renal failure at the time of enrollment.

CONCLUSION

The use of gadolinium-based contrast agent for thoracic CTA using a 64 MDCT provides diagnostic quality examinations in all patients with improved image quality compared to a 16 MDCT. No complication other than transient alteration of renal function was observed. Because the likelihood of developing NSF may vary with the type of gadolinium-based contrast agent used, the least toxic agent should be used.

Safety of gadoversetamide in patients with acute and chronic myocardial infarction

PURPOSE

To assess the safety data from two large, multicenter, phase 2 trials on the use of gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO) as a contrast agent in delayed hyperenhancement magnetic resonance imaging (DE-MRI) in patients with acute and chronic myocardial infarction (MI).

MATERIALS AND METHODS

The study population from both trials comprised 577 patients who were randomly assigned to one of four dose groups (0.05, 0.1, 0.2, or 0.3 mmol/kg) before undergoing DE-MRI. Safety evaluations included physical and electrocardiographic (ECG) examinations. Vital signs, laboratory values, adverse events (AE), and serious adverse events (SAE) were monitored before and after contrast administration.

RESULTS

Of the 577 patients who received gadoversetamide, 124 (21.5%) reported a total of 164 AEs; most were mild (139 AEs; 84.8%) or moderate (25 AEs; 15.2%). ECG-related changes were the most frequent AE. Site investigators judged only eight AEs as likely related to gadoversetamide and only two of the eight as clinically relevant. Further evaluation suggested neither AE was related to gadoversetamide. Two SAEs were reported, but none was judged related to gadoversetamide by the site investigators.

CONCLUSION

Gadoversetamide is safe for use in patients with acute or chronic MI up to a dose of 0.3 mmol/kg.

MRI safety update 2008: part 1, MRI contrast agents and nephrogenic systemic fibrosis

OBJECTIVE

This article is the first part of a two-part series on MRI safety. In this article, part 1, the topic of MRI contrast agents and nephrogenic systemic fibrosis (NSF) is addressed.

CONCLUSION

To prevent incidents and accidents associated with MRI, it is necessary to regularly revisit the safety topics that directly impact patient management especially with respect to the subjects that are "new" (e.g., MRI contrast agents and NSF), those that should be reassessed because of recent changes, topics that deserve emphasis because of controversy or confusion, and information that should be considered in light of new findings.

Pharmacokinetics of gadoversetamide injection, a gadolinium-based contrast agent, in pediatric patients

OBJECTIVE

The pharmacokinetics of gadoversetamide were examined in pediatric patients scheduled to undergo contrast-enhanced MRI of the central nervous system.

MATERIALS AND METHODS

One hundred patients received an intravenous injection of gadoversetamide at a dose of 0.1 mmol/kg for a contrast-enhanced MRI procedure. A subpopulation of 30 patients were enrolled to evaluate the pharmacokinetics of gadoversetamide in patients 2-11 and 12-18 years of age. Serial blood and urine samples were collected before and after the administration of gadoversetamide.

RESULTS

The terminal half-life, initial concentration and area under the curve assessments for gadoversetamide showed no significant (P>.05) differences between the age groups or the sexes. Although no sex-related differences occurred in the volume of distribution or clearance, significant (P<.05) age-related differences were found, but once corrected for body mass or surface area the differences were no longer significant.

CONCLUSIONS

The pharmacokinetic behavior of gadoversetamide was not significantly altered by differences in age or sex in pediatric patients from 2 to 18 years of age. Although significant differences in volumes of distribution, and clearance occurred between the age groups, these differences appeared to depend on body size rather than on age in pediatric patients between 2 and 18 years of age.

Gadolinium-based contrast agents and their potential role in the pathogenesis of nephrogenic systemic fibrosis: the role of excess ligand

PURPOSE

To investigate the role of excess ligand present in gadolinium (Gd) -based contrast agents in the development of nephrogenic systemic fibrosis (NSF). Using a dosing regimen to simulate the exposure seen in patients with severe renal impairment, we investigated the effect of excess ligand on Gd-deposition and the depletion of endogenous ions.

MATERIALS AND METHODS

Gadodiamide and gadoversetamide were formulated with 0%, 5%, and 10% excess ligand. Forty-two, healthy, male Hannover Wistar rats received daily intravenous injections of each formulation over a period of 20 days. At the end of the study, histopathological analysis of the skin was performed and the concentrations of Gd, Zn, and Cu were measured in several tissues. The levels of Zn in the urine were also measured.

RESULTS

The most severe skin lesions were observed after injection of formulations containing 0% free ligand and in those animals with the highest Gd concentrations in the skin. There were no significant reductions in the levels of Zn or Cu observed in the skin; however, the levels of Zn in the urine were elevated following administration of formulations with the highest amount of excess ligand.

CONCLUSION

Our findings suggest that there is an inverse correlation between the amount of excess ligand present in Gd-containing contrast agents and the amount of Gd in the tissue, and further underline the importance of the inherent stability of these agents in the development of NSF.

The impact of NSF on the care of patients with kidney disease

The association of nephrogenic systemic fibrosis (NSF) with the use of gadolinium-based magnetic resonance contrast agents (GBMCAs) has greatly affected the care of patients with kidney disease. Nephrogenic systemic fibrosis has been reported in patients with end-stage renal disease, chronic kidney disease (CKD) and acute kidney injury. The majority of cases have occurred in patients with end-stage renal disease, but cases of NSF have been reported in CKD patients with glomerular filtration rates less than 30 mL/min/1.73 m(2). Odds ratios have ranged between 8.97 and 32.5 among patients exposed to GBMCAs. Given the significant morbidity, disability, and mortality associated with NSF, it is imperative to properly and preemptively identify those patients at risk. Patients with end-stage renal disease seem to be at highest risk, particularly those maintained on peritoneal dialysis (PD). Although there are no data to support a role for hemodialysis in reducing the risk for NSF after the administration of GBMCAs, hemodialysis is recommended within 2 to 3 hours. Patients maintained on PD and those with CKD present a challenge, as they do not typically have vascular access for hemodialysis, yet the clearance of GBMCAs is very low, and it may be prudent to consider hemodialysis especially for PD patients. Gadolinium-based magnetic resonance contrast agents are removed by dialysis, with estimates that about 99% of a dose is removed after 3 to 4 sessions of hemodialysis. The elimination half-life averaged 9 hours in patients with stage 4 CKD (glomerular filtration rate <30 mL/min/1.73 m(2)) compared with 1.5 hours in those with normal glomerular filtration rates. This prolonged elimination and longer exposure may be important factors in predisposing to NSF.

What nephrologists need to know about gadolinium

Gadolinium chelates are commonly used to improve tissue contrast in MRI. Until recently the use of gadolinium was thought to be risk-free compared with alternative contrast agents. Recent studies, however, have raised serious concerns regarding the safety of gadolinium chelates. Although safe in patients with normal kidney function, administration of these agents in people with renal dysfunction can result in up to three clinical problems that the nephrologist should be familiar with. The first is nephrogenic systemic fibrosis (NSF), which was initially observed in 1997. Although manifesting primarily in skin, NSF can also cause systemic fibrosis, leading to disabling contractures and even death. Gadodiamide is the agent that has been most frequently associated with NSF, but other chelates might also pose a risk. The second clinical problem is that gadolinium chelates cause acute kidney injury, especially at high doses required for angiography. The third problem is that several laboratory artifacts are associated with gadolinium administration, with pseudohypocalcemia being the most important. The risk of a patient experiencing all three of these complications increases as renal function declines. In light of these problems, nephrologists need to re-evaluate the risks and benefits of gadolinium administration in patients with chronic kidney disease stage 3 or greater, as well as in those with acute kidney injury.

Tissue characterization of myocardial infarction using T1rho: influence of contrast dose and time of imaging after contrast administration

PURPOSE

To determine whether contrast between acutely infarcted and normal myocardia in T1-rho-weighted cine TFE (T1rho-TFE) and delayed-enhancement (DE) images (measured using a metric percent enhancement (PE)) varied with the dose or time of imaging after contrast administration.

MATERIALS AND METHODS

Eighteen patients with acute myocardial infarction (AMI) were randomly divided into three groups according to the dose of gadoversetamide (0.1, 0.2, or 0.3 mmol/kg) administered. After contrast administration, T1rho-TFE images were acquired at five and 40 minutes, and DE images were acquired at 10 and 30 minutes.

RESULTS

For T1rho-TFE imaging the PE values at 40 minutes were 70+/-14, 98+/-14, and 105+/-41 at 0.1, 0.2, and 0.3 mmol/kg dose levels, which were significantly greater than the corresponding PEs at five minutes after contrast administration (44+/-12, 71+/-14, and 36+/-13). For DE and T1rho-TFE imaging the dose of contrast agent did not significantly affect the PE. However, with DE the PE tended to increase with the dose. At all dose levels, irreversible injury was more conspicuous in T1rho-TFE images acquired at 40 minutes than at five minutes after contrast.

CONCLUSION

In T1rho-TFE, acute infarction was more conspicuous in images acquired at a later time point, and the PE did not vary with the contrast dose.

Multi–Detector Row CT Angiography of Pulmonary Circulation with Gadolinium-based Contrast Agents: Prospective Evaluation in 60 Patients

PURPOSE

To prospectively evaluate gadolinium dose safety and effectiveness for 16-detector pulmonary computed tomographic (CT) angiography.

MATERIALS AND METHODS

Ethics committee approval and informed consent were obtained. Sixty patients with contraindications to iodine underwent CT of the pulmonary circulation with 0.5 mmol/L gadolinium chelate given at either 0.3 (n = 29, group A) or 0.4 (n = 31, group B) mmol/kg; clinical and biologic tolerances were evaluated. Enhancement of central and segmental pulmonary arteries was measured (poor enhancement, <100 HU; good, 100-150 HU; excellent, >150 HU). Subsegmental artery enhancement was assessed as similar or inferior to that of segmental arteries. Confidence in analysis of the pulmonary arterial bed was graded according to arterial enhancement: Grades 1-3, diagnostic images; grade 4, nondiagnostic. The main effectiveness parameter for comparison between groups A and B was diagnostic value of CT angiograms. Nonparametric statistics were used to analyze results.

RESULTS

The mean (+/- standard deviation) contrast material volume was 50.09 mL +/- 8.45 (all patients: range, 30-64 mL; group A: 46.54 mL +/- 8.59; group B: 53.42 mL +/- 6.92). Diagnostic images were obtained in 55 (92%) patients, and confident analysis of pulmonary arteries to the subsegmental level was achieved in 26 (grade 1, 44%) and to the segmental level, in 21 (grade 2, 35%). Mean attenuation was higher in group B than in group A in central (180.61 HU +/- 53.85 vs 148.14 HU +/- 52.61; P = .04) and segmental (201.59 HU +/- 54.70 vs 164.73 HU +/- 59.26; P = .03) arteries. Number of diagnostic CT angiograms was higher (P = .02) in group B (n = 31 [100%]) than in group A (n = 24 [83%]). In both groups, mean enhancement of pulmonary arteries was significantly higher at 80 or 100 kV than at 120 kV. Renal function was impaired in two group A patients.

CONCLUSION

Gadolinium chelates may be used as an alternative CT contrast agent in patients who cannot receive iodine.

Safety and Effectiveness of Gadolinium-enhanced Multi–Detector Row Spiral CT Angiography of the Chest: Preliminary Results in 37 Patients with Contraindications to Iodinated Contrast Agents

PURPOSE

To prospectively evaluate the safety and effectiveness of gadolinium-enhanced multi-detector row spiral computed tomographic (CT) angiography of the pulmonary circulation by using two gadolinium doses in patients with contraindications to iodinated contrast agents.

MATERIALS AND METHODS

Study was approved by the Ethics Committee, and written informed consent was obtained. Thirty-seven patients (20 men, 17 women) with contraindications to iodinated contrast agents (allergic reactions, n = 27; impaired renal function, n = 10) underwent CT angiography of the pulmonary circulation in search of acute pulmonary embolism (n = 28) or for management of tumoral disease (n = 9). CT angiography was performed (a) with four-detector row (n = 19) or 16-detector row (n = 18) scanners; (b) at randomly assigned gadolinium doses of either 0.3 mmol per kilogram of body weight (n = 19) or 0.4 mmol/kg (n = 18); and (c) with a systematic evaluation of clinical and biologic tolerance of gadolinium. Comparison of percentages between group 1 and group 2 scans was performed with the chi2 or the Fisher exact test. An unpaired Wilcoxon rank sum test was used for numeric variables. P < .05 was considered to indicate a significant difference.

RESULTS

The mean (+/- standard deviation) volume of gadopentetate dimeglumine administered in the overall study group was 48 mL +/- 9.6 (range, 29-65 mL). The level of maximal enhancement in the pulmonary arteries was significantly higher in group 2 than in group 1 (215.8 HU +/- 95 vs 141.3 HU +/- 44) (P = .02) and was maintained throughout the entire region of interest in a greater number of examinations in group 2 than in group 1 (n = 16 [89%] vs n = 2 [10.5%]) (P < .0001). The number of diagnostic CT angiograms was significantly higher in group 2 than in group 1 (n = 17 [94%] vs n = 13 [68%]) (P = .007). Significant but transient reduction of creatinine clearance was observed in one patient with preexisting moderate chronic renal failure (0.3 mmol/kg gadolinium dose).

CONCLUSION

High-quality gadolinium-enhanced CT angiograms require the use of 16-detector row CT technology; the doses administered did not alter the renal function except transiently in one patient.

Measurement of Serum Calcium Concentration after Administration of Gadoversetamide in Dogs

PURPOSE

To measure serum calcium concentration with three different analytic methods after administration of gadoversetamide and three other gadolinium chelates in dogs.

MATERIALS AND METHODS

Six dogs were injected with 0.1-, 0.3-, 1.0-, and 3.0-mmol/kg doses of gadoversetamide; 1.0-mmol/kg doses of gadodiamide, gadopentetate, and gadoteridol; and a 6-mL/kg dose of saline. Baseline blood samples were collected before injection; 5, 15, 30, and 60 minutes after each treatment; and 2, 4, 6, 12, and 24 hours after each treatment. Serum calcium levels were measured with inductively coupled plasma mass spectrometry, an arzenazo III dye assay, and an orthocresolphalthalin (OCP) complexone system. Analysis of variance coupled with the Dunnett procedure was used to compare serum calcium concentrations at different time points after injection with baseline values.

RESULTS

Administration of gadoversetamide caused no decrease in serum calcium levels, as measured with inductively coupled plasma mass spectrometry or arzenazo III analytic techniques. In contrast, OCP assays showed a significant (P <.05) decrease in serum calcium values after administration of gadoversetamide. The decrease in serum calcium values peaked immediately after injection, and serum calcium values quickly returned to baseline. Injection of gadodiamide caused a significant (P <.05) decrease in the value of serum calcium when analyzed with the OCP technique but not when analyzed with inductively coupled plasma mass spectrometry or arzenazo III assays. In contrast, administration of gadopentetate or gadoteridol produced no significant change in serum calcium values, regardless of analytic method.

CONCLUSION

Gadoversetamide and gadodiamide caused a transient artifact in measurement of serum calcium levels with an OCP assay but not with an arzenazo III technique or inductively coupled plasma mass spectrometry. The presence of gadopentetate or gadoteridol in the blood did not affect measurement of serum calcium levels.

Pharmacokinetics and safety of the MRI contrast agent gadoversetamide injection (OptiMARK) in healthy pediatric subjects

RATIONALE AND OBJECTIVE

This clinical trial examined the pharmacokinetics of gadoversetamide, a magnetic resonance imaging contrast agent, in normal pediatric subjects.

MATERIALS AND METHODS

Seventeen healthy pediatric subjects received a single intravenous injection of gadoversetamide (0.1 mmol/kg, 0.2 mL/kg). Sixteen subjects that were evaluable for pharmacokinetic analysis fell into 2 stratified age groups: 2 years to <5 years and 5 years to <18 years of age. Serum samples were analyzed for total gadolinium as a measure of gadoversetamide concentration.

RESULTS

Statistical analysis demonstrated significant (P < 0.05) age-related trends in the mean elimination half-life (t 1/2) of gadolinium with the older group having a slightly longer t 1/2 (1.39 hours) than the younger group (1.19 hours). No age-related changes occurred in volume of distribution or total body clearance, when normalized to body weight or body surface area.

CONCLUSIONS

Based on this preliminary pharmacokinetic assessment, no adjustment from the approved adult gadoversetamide dose of 0.1 mmol/kg should be necessary for children aged 2 or older.

Safety assessment of gadoversetamide (OptiMARK®) administered by power injector

PURPOSE

To evaluate the safety of OptiMARK (gadoversetamide injection) administered via power injector.

MATERIALS AND METHODS

The study population included 144 healthy volunteers aged 18 years or older randomly assigned to one of seven treatment groups (N = 20/group). The safety assessment was based on changes in physical examination, vital signs, electrocardiograms (ECGs), standard clinical laboratory tests, and adverse events (AEs) through a 24-hour postinjection period.

RESULTS

OptiMARK caused no serious AEs or unexpected changes in physical examinations or laboratory parameters. The changes observed in vital signs and ECG intervals did not vary with changes in injection rate and were not significantly (P < 0.05) different from those elicited by saline administration at the same rates.

CONCLUSION

This study demonstrated the safety of OptiMARK when administered via a power injector at rates of 2, 4, and 6 mL/second.

Low-dose gadobenate dimeglumine versus standard dose gadopentetate dimeglumine for contrast-enhanced magnetic resonance imaging of the liver: an intra-individual crossover comparison

RATIONALE AND OBJECTIVES

Gadobenate dimeglumine (Gd-BOPTA) has a two-fold higher T1 relaxivity compared with gadopentetate dimeglumine (Gd-DTPA) and can be used for both dynamic and delayed liver MRI. This intraindividual, crossover study was conducted to compare 0.05 mmol/kg Gd-BOPTA with 0.1 mmol/kg Gd-DTPA for liver MRI.

MATERIALS AND METHODS

Forty-one patients underwent two identical MR examinations separated by >or= 72 hours. Precontrast T1-FLASH-2D and T2-TSE sequences and postcontrast T1-FLASH-2D sequences were acquired during the dynamic and delayed (1-2 hours) phases after each contrast injection. Images were evaluated on-site by two independent, blinded off-site readers in terms of confidence for lesion detection, lesion number, character and diagnosis, enhancement pattern, lesion-to-liver contrast, and benefit of dynamic and delayed scans. Additional on-site evaluation was performed of the overall diagnostic value of each agent.

RESULTS

Superior diagnostic confidence was noted by on-site investigators and off-site assessors 1 and 2 for 6, 4 and 2 patients with Gd-BOPTA, and for 3, 1 and 2 patients with Gd-DTPA, respectively. No consistent differences were noted for other parameters on dynamic phase images whereas greater lesion-to-liver contrast was noted for more patients on delayed images after Gd-BOPTA. More correct diagnoses of histologically confirmed lesions (n = 26) were made with the complete Gd-BOPTA image set than with the complete Gd-DTPA set (reader 1: 68% vs. 59%; reader 2: 78% vs. 68%). The overall diagnostic value was considered superior after Gd-BOPTA in seven patients and after Gd-DTPA in one patient.

CONCLUSION

The additional diagnostic information on delayed imaging, combined with the possibility to use a lower overall dose to obtain similar diagnostic information on dynamic imaging, offers a distinct clinical advantage for Gd-BOPTA for liver MRI.

Pharmacokinetics and safety of gadobenate dimeglumine (multihance) in subjects with impaired liver function

RATIONALE AND OBJECTIVES

To characterize the pharmacokinetics of gadolinium and to evaluate the safety of gadobenate dimeglumine (Gd-BOPTA) compared with placebo, in subjects with impaired liver function.

METHODS

Volunteer adult subjects with hepatic impairment (Child-Pugh classification B or C) received, randomly and in double-blind fashion, either 0.1 mmol/kg gadobenate dimeglumine (n = 11) or placebo (n = 5) by intravenous injection. Blood and urine gadolinium concentrations were determined by ICP-AES and data were analyzed by compartmental and noncompartmental modeling. A full safety evaluation was performed. No magnetic resonance imaging was performed.

RESULTS

A bi-exponential model fit the gadolinium blood concentration-time data for 10 of 11 subjects administered Gd-BOPTA. The mean (CV%) distribution and elimination half-lives for these subjects were 0.18 (71.9) and 2.18 (44.2) hours, respectively. Non-parametric analysis of all 11 subjects revealed a mean (CV%) area under the curve [0-inf] of 138 (41.9) microg(Gd).h/mL. Mean (CV%) values for blood clearance, steady-state volume of distribution, and renal clearance were 172 (36.0) mL/minute, 22.9 (16.7) L, and 142 (49.0) mL/minute, respectively. A mean (CV%) of approximately 80% (24.5) of the administered dose was excreted in urine during 60 to 72 hours. No safety concerns were apparent.

CONCLUSION

Hepatic impairment did not modify the pharmacokinetics of gadobenate dimeglumine compared with values reported elsewhere for healthy subjects. The contrast agent was well tolerated and safe with an overall incidence of adverse events comparable to that of placebo.

Double-blind, efficacy evaluation of gadobenate dimeglumine, a gadolinium chelate with enhanced relaxivity, in malignant lesions of the brain

BACKGROUND AND PURPOSE

The diagnostic efficacy of gadobenate dimeglumine (Gd BOPTA) was compared with that of gadodiamide (Gd DTPA-BMA) in patients with primary malignant tumors or metastases of the brain.

METHODS

A subset of patients was evaluated from the 410 enrolled in the United States in phase III central nervous system clinical trials with gadobenate dimeglumine. From these trials, there were 82 patients with intraaxial malignant neoplasms of the brain, the focus of the current study. Patients were randomized to one of three incremental dosing regimens. Imaging with gadodiamide at doses of 0.1 and 0.3 mmol/kg was compared with gadobenate dimeglumine at doses of 0.05 and 0.15 mmol/kg and at doses of 0.1 and 0.2 mmol/kg. The on-site physician, patient, and all off-site reviewers were blinded to the agent injected and the administered dose. Scans were obtained before contrast administration and within 5 minutes after administration of each dose. The two contrast injections in any one patient were separated by 15 minutes. An independent laboratory performed signal intensity measurements. The magnetic resonance (MR) films were evaluated for level of diagnostic information, number of lesions detected, and confidence in MR imaging diagnosis by two independent board-certified neuroradiologists unaffiliated with any study site.

RESULTS

The lesion-to-brain signal intensity ratio after a dose of 0.1 mmol/kg gadobenate dimeglumine was higher than that after a dose of 0.1 mmol/kg gadodiamide, with this result statistically significant (P = 0.02). After the second dose of contrast, results were comparable in all three groups. The level of diagnostic information contained on the MR films increased significantly for all three groups from pre- to postcontrast for both the first and second administered doses. In between-group comparisons, the level of diagnostic information was similar after the first contrast dose for all three dosing regimens. This was also true after the second contrast dose. For all three groups, the number of lesions detected increased significantly postdose (whether first or second). Confidence in MR diagnosis increased from predose to postdose for all three groups, with no statistically significant difference between groups.

CONCLUSION

Gadobenate dimeglumine, used at slightly lower doses, is comparable to gadodiamide in terms of efficacy in imaging of malignant intraaxial brain lesions. As with other gadolinium chelates, higher doses (0.15 and 0.2 mmol/kg) of gadobenate dimeglumine offer greater diagnostic information.

The OptiMARK clinical development program: summary of safety data

PURPOSE

To describe and summarize the safety data from the OptiMARK clinical development program.

MATERIALS AND METHODS

In the 18 clinical studies comprising the clinical program, doses ranging from 0.1 to 0.7 mmol/kg were administered to healthy adult volunteers, patients with hepatic or renal impairment, and patients with confirmed or highly suspected central nervous system (CNS), liver, breast, vascular, bone, or soft tissue pathologies. A total of 2038 injections of OptiMARK, Magnevist, or placebo were administered to 1684 subjects. Safety assessments were performed at appropriate intervals during all Phase 1, 2, and 3 studies.

RESULTS

Of the 1684 subjects exposed to a study drug or placebo in the clinical development program, 646 subjects experienced 1293 adverse events. Thirty-one percent of the OptiMARK injections were associated with an adverse event. In comparison, 35% of Magnevist injections and 48% of placebo injections were associated with at least one adverse event.

CONCLUSIONS

OptiMARK was safe and well-tolerated with a safety profile similar to that of Magnevist.

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.

Renal tolerance of a neutral gadolinium chelate (gadobutrol) in patients with chronic renal failure: results of a randomized study

PURPOSE

To assess the renal tolerance of 1.0 mol/L gadobutrol as an electrically neutral contrast agent at magnetic resonance (MR) imaging in patients with impaired renal function.

MATERIALS AND METHODS

Twenty-one patients with impaired renal function were enrolled in this prospective randomized study and classified into two subgroups according to their creatinine clearance: group 1 (n = 12), less than 80 mL/min (<1.33 mL/sec) and greater than 30 mL/min (>0.50 mL/sec); group 2 (n = 9), less than 30 mL/min (<0.50 mL/sec) and not requiring dialysis. Gadobutrol (1.0 mol/L) was injected intravenously at randomly assigned doses of either 0.1 or 0.3 mmol per kilogram of body weight. Changes in vital signs, clinical chemistry, and urinalysis results, including creatinine clearance, were monitored before, at 6 hours, and then every 24 hours until 72 hours (group 1) or 120 hours (group 2) after intravenous injection of gadobutrol. Hematologic results were checked every other day.

RESULTS

No serious adverse event occurred, and no clinically relevant changes in vital signs, hematologic results, clinical chemistry, or urinalysis results were detected in the observation period. Markers for glomerular filtration (creatinine, cystatin C, beta2-microglobulin, creatinine clearance) and tubular function (N-acetyl-beta-D-glucosaminidase, alpha1-microglobulin) were unaffected by gadobutrol in both groups.

CONCLUSION

Gadobutrol did not affect renal function and, therefore, proved to be a safe MR contrast agent in patients with impaired renal function. Even in patients with marginal excretory function (creatinine clearance, <30 mL/min [<0.50 mL/sec]), prehydration or treatment with diuretics or hemodialysis are not required after the administration of gadobutrol.

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA)

RATIONALE AND OBJECTIVES

The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system.

METHODS

Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques.

RESULTS

No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation.

CONCLUSIONS

Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.