Non-clinical assessment of safety and gadolinium deposition after cumulative administration of gadobenate dimeglumine (MultiHance®) to neonatal and juvenile rats

Preclinical Safety Assessment of Gadopiclenol: A High-Relaxivity Macrocyclic Gadolinium-Based MRI Contrast Agent

OBJECTIVE

Gadopiclenol is a new high-relaxivity macrocyclic gadolinium-based contrast agent for magnetic resonance imaging of the central nervous system and other body regions. The product has been approved by US Food and Drug Administration and is currently being evaluated by European Medicines Agency. For risk assessment of the single diagnostic use in humans, the safety profile of gadopiclenol was evaluated with a series of preclinical studies.

MATERIALS AND METHODS

With exception of dose-ranging studies, all safety pharmacology and toxicology studies were performed in compliance with Good Laboratory Practice principles. Safety pharmacology studies were conducted to assess potential effects on cardiovascular (in vitro and in dogs), respiratory (in rats and guinea pigs), neurological (in rats), and renal endpoints (in rats). Toxicology studies were also performed to investigate acute toxicity (in rats and mice), extended single-dose (in rats and dogs) and repeated-dose toxicity (in rats and dogs), reproductive (in rats), developmental (in rats and rabbits) and juvenile toxicity (in rats), as well as genotoxicity (in vitro and in rats), local tolerance (in rabbits), potential immediate hypersensitivity (in guinea pigs), and potential tissue retention of gadolinium (in rats).

RESULTS

Safety pharmacology studies conducted at high intravenous (IV) doses showed a satisfactory tolerance of gadopiclenol in the main body systems. After either single or repeated IV dosing (14 and 28 days) in rats and dogs, gadopiclenol was well tolerated even at high doses. The no-observed-adverse-effect level values (ie, the highest experimental dose without adverse effects) representing between 8 times in rats and 44 times in dogs (based on the exposure), the exposure achieved in humans at the intended diagnostic dose, provide a high safety margin. No or only minor and reversible effects on body weight, food consumption, clinical signs, clinical pathology parameters, or histology were observed at the highest doses. The main histological finding consists in renal tubular vacuolations (exacerbated after repeated exposure), which supports a well-known finding for this class of compounds that has no physiological consequence on kidney function. Reproductive toxicity studies showed no evidence of effects on reproductive performance, fertility, perinatal and postnatal development in rats, or reproductive development in rats or rabbits. The safety profile of gadopiclenol in juvenile rats was satisfactory like in adults. Gadopiclenol was not genotoxic in vitro in the Ames test, a mouse lymphoma assay, and a rat in vivo micronucleus test. There were no signs of local intolerance at the injection site after IV and intra-arterial administration in rabbits. However, because of minor signs of intolerance after perivenous administration, misadministration must be avoided. Gadopiclenol exhibited no signs of potential to induce immediate hypersensitivity in guinea pigs.

CONCLUSIONS

High safety margins were observed between the single diagnostic dose of 0.05 mmol/kg in humans and the doses showing effects in animal studies. Gadopiclenol is, therefore, well tolerated in various species (mice, rats, dogs, rabbits, and guinea pigs). All observed preclinical data support the clinical approval.

Evaluation of gadolinium-based contrast agents in juvenile CD-1 mice including behavioral evaluations

INTRODUCTION

Seven gadolinium-based contrast agents (GBCAs), four linear and three macrocyclic, were evaluated for potential effects on development, including behavior of juvenile CD-1 mice.

METHODS

The GBCAs were administered via intravenous injection once daily on postnatal day (PND) 9, 12, 15, 18, and 21 (PND 1 was the day of delivery) at doses up to twice the human equivalent clinical dose (i.e., 0.63 mmol Gd/kg for gadoxetate disodium and 2.5 mmol Gd/kg for the other GBCAs). Mice were bled for evaluation of exposure (plasma) to gadolinium (Gd) on PND 9, 12, and 70. At scheduled euthanasia, the liver, spleen, brain, skin (dorsal surface), bone (left femur), and kidneys were excised from up to six mice/sex/group on PND 10, 22, or 70 for the determination of Gd levels and histopathological analysis. All mice were monitored for toxicity, growth and survival, sexual maturation, and behavior.

CONCLUSION

Gd was quantifiable in the brain tissues with levels declining over time. There was no long-term effect on the growth and development for mice exposed to any of the GBCAs. There was no impact on neurodevelopment as assessed by brain histology and validated neurobehavioral tests, including a functional observational battery, motor activity, and learning and memory as evaluated in the Morris water maze. For all GBCAs, the highest dose tested represented the no-observable-adverse-effect level in juvenile mice.

Evaluation of gadolinium-based contrast agents in pregnant CD-1 mice and subsequent in utero exposure of the developing offspring, including behavioral evaluations

INTRODUCTION

The offspring of CD-1 mice exposed during pregnancy to one of seven gadolinium-based contrast agents (GBCAs) were evaluated for potential effects on postnatal development and behavior. The GBCAs, comprising four linear (gadopentetate dimeglumine, gadodiamide, gadobenate dimeglumine, and gadoxetate disodium) and three macrocyclic (gadoterate meglumine, gadoteridol, and gadobutrol), were administered via intravenous injection once daily from Gestation Day 6 through 17 following confirmed mating (Day 0) at doses of at least twice the human equivalent recommended clinical dose (i.e., 0.63 mmol Gd/kg for gadoxetate disodium and 2.5 mmol Gd/kg for the other GBCAs). All dams were allowed to deliver naturally. F0 generation females were monitored for maternal toxicity and gadolinium (Gd) levels in blood and brain. Offspring were evaluated for Gd levels in blood and brain at birth and on Day 70 postpartum. F1 generation mice were evaluated for survival and growth preweaning. Selected pups/litter were evaluated postweaning for sexual maturation, growth, and behavior. Gd was quantifiable in the brain of the F1 offspring on PND 1, with levels declining over time. There was no long-term effect of any GBCA on the growth and development of any offspring. There was no impact on neurodevelopment, as assessed by brain histology and validated neurobehavioral tests, including a battery of functional observational tests, motor activity, and learning and memory as evaluated in the Morris water maze.

CONCLUSION

At the end of the postweaning period, the highest dose tested was considered the no-observable-adverse-effect level (NOAEL) in the F0 and F1 offspring for all tested GBCAs.

Skin Toxicity After Exposure to Gadolinium-Based Contrast Agents in Normal Renal Function, Using Clinical Approved Doses: Current Status of Preclinical and Clinical Studies

OBJECTIVES

The aim of this study was to summarize the current preclinical and clinical evidence on the association between exposure to gadolinium (Gd) compounds and skin toxicity in a setting similar to clinical practice.

MATERIALS AND METHODS

A search of MEDLINE and PubMed references from January 2000 to December 2022 was performed using keywords related to gadolinium deposition and its effects on the skin, such as "gadolinium," "gadolinium-based contrast agents," "skin," "deposition," and "toxicity." In addition, cross-referencing was added when appropriate. For preclinical in vitro studies, we included all the studies that analyzed the response of human dermal fibroblasts to exposure to various gadolinium compounds. For preclinical animal studies and clinical studies, we included only those that analyzed animals or patients with preserved renal function (estimated glomerular filtration rate >30 mL/min/1.73 m 2 ), using a dosage of gadolinium-based contrast agents (GBCAs) similar to that commonly applied (0.1 mmol/kg).

RESULTS

Forty studies were selected. Preclinical findings suggest that Gd compounds can produce profibrotic responses in the skin in vitro, through the activation and proliferation of dermal fibroblasts and promoting their myofibroblast differentiation. Gadolinium influences the process of collagen production and the collagen content of skin, by increasing the levels of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1. Preclinical animal studies show that Gd can deposit in the skin with higher concentrations when linear GBCAs are applied. However, these deposits decrease over time and are not associated with obvious macroscopic or histological modifications. The clinical relevance of GBCAs in inducing small fiber neuropathy remains to be determined. Clinical studies show that Gd is detectable in the skin and hair of subjects with normal renal function in higher concentrations after intravenous administration of linear compared with macrocyclic GBCA. However, these deposits decrease over time and are not associated with cutaneous or histological modifications. Also, subclinical dermal involvement related to linear GBCA exposure may be detectable on brain MRI. There is no conclusive evidence to support a causal relationship between GBCA administration at the clinical dose and cutaneous manifestations in patients with normal renal function.

CONCLUSIONS

Gadolinium can produce profibrotic responses in the skin, especially acting on fibroblasts, as shown by preclinical in vitro studies. Gadolinium deposits are detectable in the skin even in subjects with normal renal function with higher concentrations when linear GBCAs are used, as confirmed by both preclinical animal and human studies. There is no proof to date of a cause-effect relationship between GBCA administration at clinical doses and cutaneous consequences in patients with normal renal function. Multiple factors, yet to be determined, should be considered for sporadic patients with normal renal function who develop clinical skin manifestations temporally related to GBCA administration.

Gadolinium: pharmacokinetics and toxicity in humans and laboratory animals following contrast agent administration

Gadolinium-based contrast agents (GBCAs) have transformed magnetic resonance imaging (MRI) by facilitating the use of contrast-enhanced MRI to allow vital clinical diagnosis in a plethora of disease that would otherwise remain undetected. Although over 500 million doses have been administered worldwide, scientific research has documented the retention of gadolinium in tissues, long after exposure, and the discovery of a GBCA-associated disease termed nephrogenic systemic fibrosis, found in patients with impaired renal function. An understanding of the pharmacokinetics in humans and animals alike are pivotal to the understanding of the distribution and excretion of gadolinium and GBCAs, and ultimately their potential retention. This has been well studied in humans and more so in animals, and recently there has been a particular focus on potential toxicities associated with multiple GBCA administration. The purpose of this review is to highlight what is currently known in the literature regarding the pharmacokinetics of gadolinium in humans and animals, and any toxicity associated with GBCA use.

MR Imaging Safety Considerations of Gadolinium-Based Contrast Agents: Gadolinium Retention and Nephrogenic Systemic Fibrosis

Gadolinium (Gd)-based contrast agents (GBCAs) have revolutionized of MR imaging, enabling physicians to obtain life-saving medical information that often cannot be obtained with unenhanced MR imaging or other imaging modalities. Since regulatory approval in 1988, more than 450 million intravenous GBCA doses have been administered worldwide, with an extremely favorable pharmacologic safety profile. Recent evidence has demonstrated, however, that a small fraction of Gd is retained in human tissues. No direct correlation between Gd retention and clinical effects has been confirmed; however, a subset of patients have attributed various symptoms to GBCA exposure. This review details current knowledge regarding GBCA safety.

Repeat and single dose administration of gadodiamide to rats to investigate concentration and location of gadolinium and the cell ultrastructure

Gadolinium based contrast agents (GBCA) are used to image patients using magnetic resonance (MR) imaging. In recent years, there has been controversy around gadolinium retention after GBCA administration. We sought to evaluate the potential toxicity of gadolinium in the rat brain up to 1-year after repeated gadodiamide dosing and tissue retention kinetics after a single administration. Histopathological and ultrastructural transmission electron microscopy (TEM) analysis revealed no findings in rats administered a cumulative dose of 12 mmol/kg. TEM-energy dispersive X-ray spectroscopy (TEM-EDS) localization of gadolinium in the deep cerebellar nuclei showed ~ 100 nm electron-dense foci in the basal lamina of the vasculature. Laser ablation-ICP-MS (LA-ICP-MS) showed diffuse gadolinium throughout the brain but concentrated in perivascular foci of the DCN and globus pallidus with no observable tissue injury or ultrastructural changes. A single dose of gadodiamide (0.6 mmol/kg) resulted in rapid cerebrospinal fluid (CSF) and blood clearance. Twenty-weeks post administration gadolinium concentrations in brain regions was reduced by 16-72-fold and in the kidney (210-fold), testes (194-fold) skin (44-fold), liver (42-fold), femur (6-fold) and lung (64-fold). Our findings suggest that gadolinium does not lead to histopathological or ultrastructural changes in the brain and demonstrate in detail the kinetics of a human equivalent dose over time in a pre-clinical model.

Dose-Lowering in Contrast-Enhanced MRI of the Central Nervous System: A Retrospective, Parallel-Group Comparison Using Gadobenate Dimeglumine

Background

Concerns over gadolinium (Gd) retention encourage the use of lower Gd doses. However, lower Gd doses may compromise imaging performance. Higher relaxivity gadobenate may be suited to reduced dose protocols.

Purpose

To compare 0.05 mmol/kg and 0.1 mmol/kg gadobenate in patients undergoing enhanced MRI of the central nervous system (CNS).

Study Type

Retrospective, multicenter.

Population

Three hundred and fifty‐two patients receiving 0.05 (n = 181) or 0.1 (n = 171) mmol/kg gadobenate.

Field Strength/Sequences

1.5 T and 3.0 T/precontrast and postcontrast T1‐weighted spin echo/fast spin echo (SE/FSE) and/or gradient echo/fast field echo (GRE/FFE); precontrast T2‐weighted FSE and T2‐FLAIR.

Assessment

Images of patients with extra‐axial lesions at 1.5 T or any CNS lesion at 3.0 T were reviewed by three blinded, independent neuroradiologists for qualitative (lesion border delineation, internal morphology visualization, contrast enhancement; scores from 1 = poor to 4 = excellent) and quantitative (lesion‐to‐brain ratio [LBR], contrast‐to‐noise ratio [CNR]; SI measurements at regions‐of‐interest on lesion and normal parenchyma) enhancement measures. Noninferiority of 0.05 mmol/kg gadobenate was determined for each qualitative endpoint if the lower limit of the 95% confidence interval (CI) for the difference in precontrast + postcontrast means was above a noninferiority margin of −0.4.

Statistical Tests

Student's t‐test for comparison of mean qualitative endpoint scores, Wilcoxon signed rank test for comparison of LBR and CNR values; Wilcoxon rank sum test for comparison of SI changes. Tests were significant for P < 0.05.

Results

The mean change from precontrast to precontrast + postcontrast was significant for all endpoints. Readers 1, 2, and 3 evaluated 304, 225, and 249 lesions for 0.05 mmol/kg gadobenate, and 382, 309, and 298 lesions for 0.1 mmol/kg gadobenate. The lower limit of the 95% CI was above −0.4 for all comparisons. Significantly, higher LBR and CNR was observed with the higher dose.

Data Conclusion

0.05 mmol/kg gadobenate was noninferior to 0.1 mmol/kg gadobenate for lesion visualization.

Evidence Level

2

Technical Efficacy

Stage 3

Comprehensive phenotyping revealed transient startle response reduction and histopathological gadolinium localization to perineuronal nets after gadodiamide administration in rats

Gadolinium based contrast agents (GBCAs) are widely used in clinical MRI since the mid-1980s. Recently, concerns have been raised that trace amounts of Gadolinium (Gd), detected in brains even long time after GBCA application, may cause yet unrecognized clinical consequences. We therefore assessed the behavioral phenotype, neuro-histopathology, and Gd localization after repeated administration of linear (gadodiamide) or macrocyclic (gadobutrol) GBCA in rats. While most behavioral tests revealed no difference between treatment groups, we observed a transient and reversible decrease of the startle reflex after gadodiamide application. Residual Gd in the lateral cerebellar nucleus was neither associated with a general gene expression pathway deregulation nor with neuronal cell loss, but in gadodiamide-treated rats Gd was associated with the perineuronal net protein aggrecan and segregated to high molecular weight fractions. Our behavioral finding together with Gd distribution and speciation support a substance class difference for Gd presence in the brain after GBCA application.

Detection of gadolinium deposition in cortical bone with ultrashort echo time T1 mapping: an ex vivo study in a rabbit model

OBJECTIVES

To investigate the capacity of ultrashort echo time (UTE) T₁ mapping to non-invasively assess gadolinium deposition in cortical bone after gadolinium-based contrast agent (GBCA) administration.

METHODS

Twenty-eight New Zealand rabbits (male, 3.0-3.5 kg) were randomly allocated into control, macrocyclic, high-dose macrocyclic, and linear GBCA groups (n = 7 for each group), and respectively given daily doses of 0.9 ml/kg bodyweight saline, 0.3 mmol/kg bodyweight gadobutrol, 0.9 mmol/kg bodyweight gadobutrol, and 0.3 mmol/kg bodyweight gadopentetate dimeglumine for five consecutive days per week over a period of 4 weeks. After a subsequent 4 weeks of recovery, the rabbits were sacrificed and their tibiae harvested. T₁ value of cortical bone was measured using a combination of UTE actual flip angle imaging and variable repetition time on a 7T animal scanner. Gadolinium concentration in cortical bone was measured using inductively coupled plasma mass spectrometry (ICP-MS). Pearson's correlation between R₁ value (R₁ = 1/T₁) and gadolinium concentration in cortical bone was assessed.

RESULTS

Bone T₁ values were significantly lower in the lower-dose macrocyclic (329.2 ± 21.0 ms, p < 0.05), higher-dose macrocyclic (316.8 ± 21.7 ms, p < 0.01), and linear (296.8 ± 24.1 ms, p < 0.001) GBCA groups compared with the control group (356.3 ± 19.4 ms). Gadolinium concentrations measured by ICP-MS in the control, lower-dose macrocyclic, higher-dose macrocyclic, and linear GBCA groups were 0.04 ± 0.02 μg/g, 2.60 ± 0.48 μg/g, 4.95 ± 1.17 μg/g, and 13.62 ± 1.55 μg/g, respectively. There was a strong positive correlation between R₁ values and gadolinium concentrations in cortical bone (r = 0.73, p < 0.001).

CONCLUSIONS

These results suggest that UTE T₁ mapping has the potential to provide a non-invasive assessment of gadolinium deposition in cortical bone following GBCA administration.

KEY POINTS

• Changes in T₁ value related to gadolinium deposition were found in bone after both linear and macrocyclic GBCA administrations. • R₁ relaxometry correlates strongly with gadolinium concentration in cortical bone. • UTE T₁ mapping provides a potential tool for non-invasively monitoring gadolinium deposition in cortical bone.

Safety and Diagnostic Efficacy of Gadobenate Dimeglumine in MRI of the Brain and Spine of Neonates and Infants

BACKGROUND AND PURPOSE

Contrast-enhanced MR imaging provides essential information for pediatric imaging applications. We evaluated gadobenate dimeglumine for contrast-enhanced MR imaging of infants younger than 2 years of age.

MATERIALS AND METHODS

Ninety children younger than 2 years of age (including 55 children younger than 1 year) who underwent enhanced MR imaging of the CNS with gadobenate dimeglumine at 0.1 mmol/kg body weight ± 25% by volume were retrospectively enrolled at 2 imaging centers. Safety data were assessed for adverse events and, when available, vital signs and electrocardiogram and clinical laboratory values obtained from 48 hours before until 48 hours after the MR imaging examination. The efficacy of gadobenate dimeglumine-enhanced MR imaging was evaluated prospectively by 3 blinded, unaffiliated readers in terms of the accuracy of combined pre- and postcontrast images relative to precontrast images alone for differentiation of tumor from non-neoplastic disease and the correct diagnosis of specific disease. Differences were tested using the McNemar test. A possible effect of dose on diagnostic accuracy was assessed using the Fisher exact test.

RESULTS

Nine nonserious adverse events were reported for 8 (8.8%) patients. Five adverse events occurred in patients 12 months of age or older. All events occurred at least 24 hours after gadobenate dimeglumine administration, and in each case, the investigating radiologist considered that there was no reasonable possibility of a relationship to gadobenate dimeglumine. No clinically meaningful changes in vital signs, electrocardiogram results, or laboratory parameters were reported. Accurate differentiation of tumor from non-neoplastic disease and exact matching of each specific MR imaging-determined diagnosis with the on-site final diagnosis were achieved in significantly more patients by each reader following evaluation of combined pre- and postcontrast images relative to precontrast images alone (91.0%-94.4% versus 75.3%-87.6%, P < .04, and 66.3%-73.0% versus 52.8%-58.4%, P < .02, respectively). No significant differences (P > .133) in diagnostic accuracy were noted between patients receiving ≤0.08 mmol/kg of gadobenate dimeglumine and patients receiving >0.08 mmol/kg of gadobenate dimeglumine.

CONCLUSIONS

Gadobenate dimeglumine is safe and effective for pediatric MR imaging.

Does Gadoterate Meglumine Cause Gadolinium Retention in the Brain of Children? A Case-Control Study

BACKGROUND

Accumulation of macrocyclic gadolinium agents in children's brains remain to be determined.

PURPOSE

To demonstrate whether there is an intracranial macrocyclic gadolinium deposition after multiple contrast-enhanced MRI with gadoterate meglumine in a pediatric population.

STUDY TYPE

Retrospective case-control.

POPULATION

In all, 45 children (age range: 5-17 years; mean, 13.7 ± 3.4 years) for the study group and 45 healthy children (age range: 5-17 years; mean, 13.7 ± 3.4 years) for the control group.

FIELD STRENGTH/SEQUENCE

T₁ - and T₂ -weighted axial images on a 1.5T scanner.

ASSESSMENT

Children with at least three enhanced brain MRIs and an age- and sex-matched control group with an unenhanced brain MRIs were compared in terms of T₁ signal intensity (SI). All patients in the study group received gadoterate meglumine intravenously (0.1 mmol/kg). SI measurements were made by drawing six regions of interest (ROIs): dentate nuclei (DN), pons, globus pallidi (GP), frontal white matter (FWM), thalamus (T), clivus, and cerebrospinal fluid (CSF) for both groups on unenhanced T₁ -weighted images.

STATISTICAL TESTS

Student's t-test was used for comparison of SI. The Pearson correlation was calculated for the correlation between the SI and the number of gadolinium administrations.

RESULTS

A significant difference was detected between two groups for DN/CSF, pons/CSF, GP/CSF, thalamus/CSF, and FWM/CSF (P < 0.001, P < 0.001, P = 0.002, P = 0.002, P = 0.024, respectively). There was no significant difference between the two groups for clivus/CSF (P = 0.15). A good correlation between the number of gadoterate meglumine administrations and the SI for DN/CSF, pons/CSF, GP/CSF, and T/CSF (r = 0.80, r = 0.73, r = 0.91, and r = 0.90, respectively) was found.

DATA CONCLUSION

A significant T₁ SI increase reflecting gadolinium retention in the brain was detected for children with at least three gadoterate meglumine administrations in this series. The number of administrations correlated well with the increased SI.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:1471-1477.

Staging of liver fibrosis using Gd-EOB-DTPA and Gd-BOPTA enhanced magnetic resonance imaging

The severity of cirrhosis is closely related to its clinical treatment. Therefore, it is important to stage liver fibrosis accurately. Although liver biopsy can accurately stage the degree of cirrhosis, it has certain limitations in clinical application because of its invasive nature. Magnetic resonance imaging (MRI) has been used in the diagnosis of liver diseases. In recent years, two new contrast agents, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) and gadobenate dimeglumine (Gd-BOPTA), have been successfully used for noninvasive liver imaging. They can be used for liver fibrosis staging and assessment of liver function. Cirrhotic patients with different liver function levels have a statistical difference in the liver parenchyma enhancement after giving contrast agents. This article briefly summarizes the progress of Gd-EOB-DTPA and Gd-BOPTA enhanced MRI in staging liver fibrosis stage.

Gadolinium Deposition in Brain: Current Scientific Evidence and Future Perspectives

In the past 4 years, many publications described a concentration-dependent deposition of gadolinium in the brain both in adults and children, seen as high signal intensities in the globus pallidus and dentate nucleus on unenhanced T1-weighted images. Postmortem human or animal studies have validated gadolinium deposition in these T1-hyperintensity areas, raising new concerns on the safety of gadolinium-based contrast agents (GBCAs). Residual gadolinium is deposited not only in brain, but also in extracranial tissues such as liver, skin, and bone. This review summarizes the current evidence on gadolinium deposition in the human and animal bodies, evaluates the effects of different types of GBCAs on the gadolinium deposition, introduces the possible entrance or clearance mechanism of the gadolinium and potential side effects that may be related to the gadolinium deposition on human or animals, and puts forward some suggestions for further research.

The inhibitory effect of gadoxetate disodium on hepatic transporters: a study using indocyanine green

OBJECTIVES

To assess the inhibitory effect of gadoxetate disodium on the transporter system using indocyanine green (ICG).

MATERIALS AND METHODS

Groups of six female B6 Albino mice were injected with the test agent (0.62 mmol/kg gadoxetate disodium) or phosphate-buffered saline (control) 10 min before injection of ICG. Identical fluorescence images were subsequently obtained to create time-efficiency curves of liver parenchymal uptake. The study was performed on hypothermic and normothermic mice. The logarithms of the absorption rate constants (logKa values) and of the elimination rate constants (logKe values) were calculated for each experimental condition, and between-group differences were compared using Student's t-test.

RESULTS

The logKe values of the test group were lower than those of the control group at both temperatures (-6.52 vs. -5.87 under hypothermic conditions and -4.54 vs. -4.14 under normothermic conditions), and both differences were statistically significant (p = 0.037, 0.015 respectively). In terms of the logKa values, although the difference did not reach statistical significance (p = 0.052), the test group had lower values than the control group under hypothermic conditions (-0.771 vs. -0.376). In normothermic mice, the logKa values for the test and control groups were 0.037 and 0.277 respectively, thus not significantly different (p = 0.404).

CONCLUSIONS

Gadoxetate disodium inhibited ICG excretion. Thus, gadoxetate disodium inhibited the ATP-binding cassette sub-family C member 2 transporter.

KEY POINTS

• Gadoxetate disodium inhibited ICG excretion. • Gadoxetate disodium tended to inhibit hepatic ICG uptake. • Drug-drug interactions of gadoxetate disodium need further investigation.