Gadolinium Presence in Rat Skin: Assessment of Histopathologic Changes Associated with Small Fiber Neuropathy.

Background The presence of gadolinium traces in the skin after administration of gadolinium-based contrast agents (GBCAs) raised safety concerns regarding a potential association with small fiber neuropathy (SFN). Purpose To investigate signs of SFN in rat foot pads by quantification of the intraepidermal nerve fiber density (IENFD) after multiple GBCA administrations and to evaluate gadolinium concentration, chemical species, and clearance. Materials and Methods Fifty rats received eight intravenous injections of either gadodiamide, gadobutrol, gadoterate, gadoteridol (8 × 0.6 mmol per kilogram of body weight), or saline (1.2 mL per kilogram of body weight), within 2 weeks and were sacrificed 5 days or 5 weeks after the last injection. IENFD was determined with protein gene product (PGP) 9.5 immunofluorescent staining and blinded and automated image analysis. The gadolinium and GBCA concentrations were measured with inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS, and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI). P values were calculated using linear contrasts of model analysis. Results The IENFD (measured as geometric mean [SD] and in number of nerve fibers per millimeter of epidermis) was not significantly altered after 5 days (saline, 8.4 [1.1]; gadobutrol, 9.7 [1.2]; gadoterate, 9.2 [1.2]; gadoteridol, 9.9 [1.3]; gadodiamide, 10.5 [1.2]) or 5 weeks (saline, 19.7 [1.4]; gadobutrol, 16.4 [1.6]; gadoterate, 14.3 [1.6]; gadoteridol, 22.2 [1.8]; gadodiamide, 17.9 [1.4]). Gadolinium skin concentrations were highest for gadodiamide after 5 days (16.0 nmol/g [1.1]) and 5 weeks (10.6 nmol/g [1.2], -33%). Macrocyclic agents were lower at 5 days (gadoteridol, 2.6 nmol/g [1.2]; gadobutrol, 2.7 nmol/g [1.1]; and gadoterate, 2.3 nmol/g [1.2]) and efficiently cleared after 5 weeks (gadoteridol, -95%; gadobutrol and gadoterate, -96%). The distribution of gadolinium and IENF did not visually overlap. For macrocyclic agents, gadolinium was found in sweat glands and confirmed to be intact chelate. Conclusion There were no signs of SFN in rat foot pads using multiple dosing regimens at two time points after administration of GBCAs. Macrocyclic GBCAs exhibited lower levels of gadolinium in the skin and were effectively eliminated within 5 weeks compared with linear gadodiamide, and intact macrocyclic GBCA was detected in sweat glands. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Clement in this issue.

First-in-human study of eliapixant (BAY 1817080), a highly selective P2X3 receptor antagonist: Tolerability, safety and pharmacokinetics.

AIMS: Neuronal hypersensitisation due to adenosine triphosphate-dependent P2X3 receptor signalling plays a significant role in several disorders including chronic cough and endometriosis. This first-in-human study of eliapixant (BAY 1817080) investigated the tolerability, safety and pharmacokinetics (PK) of single doses of eliapixant, including the effect of food and coadministration with a CYP3A inhibitor on eliapixant relative bioavailability. METHODS: In this randomised, double-blind phase I study (NCT02817100), 88 healthy male subjects received single ascending doses of immediate-release eliapixant (10-800 mg) tablets or placebo under fasted conditions, with food (low-fat continental or high-fat American breakfast) or with itraconazole (fasted state). PK parameters, dose proportionality, adverse events and taste assessments (taste strips; dysgeusia questionnaire) were evaluated. RESULTS: Eliapixant had a long half-life (23.5-58.9 h [fasted state]; 32.8-43.8 h [high-fat breakfast]; 38.9-46.0 h [low-fat breakfast]). Less than dose-proportional increases in maximum plasma concentrations (Cmax ) and area under the concentration-time curve from time 0 to infinity (AUC[0-inf] ) were observed with ascending eliapixant doses. We observed a pronounced food effect with the high-fat breakfast (4.1-fold increased Cmax ; 2.7-fold increased AUC[0-inf] ), a smaller food effect with the low-fat breakfast and a mild-to-moderate effect of itraconazole coadministration on eliapixant (1.1-1.2-fold increased Cmax ; 1.7-fold increased AUC from 0 to 72 h). Eliapixant was well tolerated with minimal impact on taste perception. CONCLUSION: The PK profile, particularly the long half-life, and favourable tolerability with no taste-related adverse events, supports the further development of eliapixant in disorders with underlying P2X3 receptor-mediated neuronal hypersensitisation.

Pharmacokinetics, Safety, and Tolerability of the α2C -Adrenoreceptor Antagonist BAY 1193397 in Healthy Male Subjects.

The α2C -adrenoreceptor antagonist BAY 1193397 is in development for the oral treatment of diabetic foot ulcers. Safety, tolerability, and pharmacokinetics of BAY 1193397 were investigated in 3 randomized, single-center phase 1 studies in healthy male subjects: a first-in-human study (single oral doses of 0.5-50 mg), a relative bioavailability and food effect study (single doses of 1 and 10 mg), and a multiple-dose escalation study (using 2 and 5 mg twice daily and 10 and 20 mg once daily for 9 consecutive days). BAY 1193397 was rapidly absorbed in the fasted state, peak concentrations were reached between 0.6 and 2 hours. The mean terminal half-life was in the range of 17 to 20 hours. Area under the plasma concentration-time curve and maximum concentration appeared to be dose proportional, with a negligible food effect. There were no high-accumulation effects of BAY 1193397 after repeated dosing. BAY 1193397 was safe and well tolerated. At supratherapeutic plasma concentrations, there were slight transient increases in norepinephrine levels, heart rate, and blood pressure that were more pronounced after a single dose compared to steady state and appeared to be maximum concentration dependent. The results of the presented studies support the conduct of subsequent clinical trials with BAY 1193397 in patients with diabetes and compromised microcirculation.

Absorption, distribution, metabolism and excretion of molidustat in healthy participants.

The absorption, distribution, metabolism and excretion of molidustat were investigated in healthy male participants. In study 1, a mass balance study, radiolabelled molidustat 25 mg (3.57 MBq) was administered as an oral solution (n = 4). Following rapid absorption, molidustat-related radioactivity was predominantly distributed in plasma rather than in red blood cells. The total recovery of the administered radioactivity was 97.0%, which was mainly excreted renally (90.7%). Metabolite M-1, produced by N-glucuronidation, was the dominant component in plasma (80.2% of the area under the concentration-time curve for total radioactivity) and was primarily excreted via urine (~85% of dose). Only minor amounts of unchanged molidustat were excreted in urine (~4%) and faeces (~6%). Study 2 investigated the absolute bioavailability and pharmacodynamics of molidustat (part 1, n = 12; part 2, n = 16). Orally administered molidustat immediate release tablets had an absolute bioavailability of 59%. Following intravenous administration (1, 5 and 25 mg), total body clearance of molidustat was 28.7-34.5 L/h and volume of distribution at steady state was 39.3-50.0 L. All doses of molidustat transiently elevated endogenous erythropoietin levels, irrespective of the route of administration. Molidustat was considered safe and well tolerated at the administered doses.

Rogaratinib: A potent and selective pan-FGFR inhibitor with broad antitumor activity in FGFR-overexpressing preclinical cancer models.

Aberrant activation in fibroblast growth factor signaling has been implicated in the development of various cancers, including squamous cell lung cancer, squamous cell head and neck carcinoma, colorectal and bladder cancer. Thus, fibroblast growth factor receptors (FGFRs) present promising targets for novel cancer therapeutics. Here, we evaluated the activity of a novel pan-FGFR inhibitor, rogaratinib, in biochemical, cellular and in vivo efficacy studies in a variety of preclinical cancer models. In vitro kinase activity assays demonstrate that rogaratinib potently and selectively inhibits the activity of FGFRs 1, 2, 3 and 4. In line with this, rogaratinib reduced proliferation in FGFR-addicted cancer cell lines of various cancer types including lung, breast, colon and bladder cancer. FGFR and ERK phosphorylation interruption by rogaratinib treatment in several FGFR-amplified cell lines suggests that the anti-proliferative effects are mediated by FGFR/ERK pathway inhibition. Furthermore, rogaratinib exhibited strong in vivo efficacy in several cell line- and patient-derived xenograft models characterized by FGFR overexpression. The observed efficacy of rogaratinib strongly correlated with FGFR mRNA expression levels. These promising results warrant further development of rogaratinib and clinical trials are currently ongoing (ClinicalTrials.gov Identifiers: NCT01976741, NCT03410693, NCT03473756).

Pharmacokinetics, Safety, and Tolerability of the Novel Chymase Inhibitor BAY 1142524 in Healthy Male Volunteers.

The orally available chymase inhibitor BAY 1142524 is currently being developed as a first-in-class treatment for left-ventricular dysfunction after myocardial infarction. Results from 3 randomized, single-center, phase 1 studies in healthy male volunteers examining the safety, tolerability, and pharmacokinetics of BAY 1142524 are summarized. In this first-in-human study, single oral doses of 1-200 mg were administered in fasted state as liquid service formulation or immediate release (IR) tablets. The relative bioavailability and the effect of a high-fat/high-calorie meal were investigated at the 5-mg dose. In a multiple-dose escalation study, doses of 5-50 mg twice daily and 100 mg once daily were given for 5 consecutive days. BAY 1142524 was safe and well tolerated and had no effects on heart rate or blood pressure compared with placebo. BAY 1142524 was absorbed with peak concentration 1-3 hours after administration for IR tablets; it was eliminated from plasma with a terminal half-life of 6.84-12.0 hours after administration of liquid service formulation or IR tablets. Plasma exposures appeared to be dose-linear, with a negligible food effect. There was only low accumulation of BAY 1142524 after multiple dosing. BAY 1142524 exhibited a pharmacokinetic profile allowing for once-daily dosing. The absence of blood pressure effects after administration of BAY 1142524 supports the combination of this novel anti-remodeling drug with existing standard of care in patients with left-ventricular dysfunction after acute myocardial infarction.

Discovery of Molidustat (BAY†85-3934): A Small-Molecule Oral HIF-Prolyl Hydroxylase (HIF-PH) Inhibitor for the Treatment of Renal Anemia.

Small-molecule inhibitors of hypoxia-inducible factor prolyl hydroxylases (HIF-PHs) are currently under clinical development as novel treatment options for chronic kidney disease (CKD) associated anemia. Inhibition of HIF-PH mimics hypoxia and leads to increased erythropoietin (EPO) expression and subsequently increased erythropoiesis. Herein we describe the discovery, synthesis, structure-activity relationship (SAR), and proposed binding mode of novel 2,4-diheteroaryl-1,2-dihydro-3H-pyrazol-3-ones as orally bioavailable HIF-PH inhibitors for the treatment of anemia. High-throughput screening of our corporate compound library identified BAY-908 as a promising hit. The lead optimization program then resulted in the identification of molidustat (BAY 85-3934), a novel small-molecule oral HIF-PH inhibitor. Molidustat is currently being investigated in clinical phase III trials as molidustat sodium for the treatment of anemia in patients with CKD.

Mass spectrometric characterization of the hypoxia-inducible factor (HIF) stabilizer drug candidate BAY 85-3934 (molidustat) and its glucuronidated metabolite BAY-348, and their implementation into routine doping controls.

The development of new therapeutics potentially exhibiting performance-enhancing properties implicates the risk of their misuse by athletes in amateur and elite sports. Such drugs necessitate preventive anti-doping research for consideration in sports drug testing programmes. Hypoxia-inducible factor (HIF) stabilizers represent an emerging class of therapeutics that allows for increasing erythropoiesis in patients. BAY 85-3934 is a novel HIF stabilizer, which is currently undergoing phase-2 clinical trials. Consequently, the comprehensive characterization of BAY 85-3934 and human urinary metabolites as well as the implementation of these analytes into routine doping controls is of great importance. The mass spectrometric behaviour of the HIF stabilizer drug candidate BAY 85-3934 and a glucuronidated metabolite (BAY-348) were characterized by electrospray ionization-(tandem) mass spectrometry (ESI-MS(/MS)) and multiple-stage mass spectrometry (MSn ). Subsequently, two different laboratories established different analytical approaches (one each) enabling urine sample analyses by employing either direct urine injection or solid-phase extraction. The methods were cross-validated for the metabolite BAY-348 that is expected to represent an appropriate target analyte for human urine analysis. Two test methods allowing for the detection of BAY-348 in human urine were applied and cross-validated concerning the validation parameters specificity, linearity, lower limit of detection (LLOD; 1-5 ng/mL), ion suppression/enhancement (up to 78%), intra- and inter-day precision (3-21%), recovery (29-48%), and carryover. By means of ten spiked test urine samples sent blinded to one of the participating laboratories, the fitness-for-purpose of both assays was provided as all specimens were correctly identified applying both testing methods. As no post-administration study samples were available, analyses of authentic urine specimens remain desirable. Copyright © 2016 John Wiley & Sons, Ltd.

Determination of nifurtimox in dog plasma by stable-isotope dilution LC-MS/MS.

BACKGROUND: Nifurtimox is a 5-nitrofuran derived antiprotozoal drug used to treat diseases caused by trypanosomes including Chagas' disease and sleeping sickness (African trypanosomiasis). Available methods for the determination of nifurtimox in plasma are tedious and of low sensitivity. For the first time, an isotope dilution HPLC/MS/MS method for the sensitive quantitation of nifurtimox down to 10.0 µg/l in plasma is described. RESULTS: Protein precipitation was used for sample preparation. Samples were analyzed on a standard triple quadrupole tandem mass spectrometer. The validated concentration range covers 10.0 µg/l (LLOQ) to 5000 µg/l. Interassay accuracy and precision (%CV) ranged from 98.4 to 101%, and 2.61 to 10.1%, respectively. CONCLUSION: The method consists of very simple sample preparation and provides unmatched sensitivity, high reproducibility and robustness enabling analysis of large sample numbers. Method performance met current guidelines on bioanalytical method validation.

Mimicking hypoxia to treat anemia: HIF-stabilizer BAY 85-3934 (Molidustat) stimulates erythropoietin production without hypertensive effects.

Oxygen sensing by hypoxia-inducible factor prolyl hydroxylases (HIF-PHs) is the dominant regulatory mechanism of erythropoietin (EPO) expression. In chronic kidney disease (CKD), impaired EPO expression causes anemia, which can be treated by supplementation with recombinant human EPO (rhEPO). However, treatment can result in rhEPO levels greatly exceeding the normal physiological range for endogenous EPO, and there is evidence that this contributes to hypertension in patients with CKD. Mimicking hypoxia by inhibiting HIF-PHs, thereby stabilizing HIF, is a novel treatment concept for restoring endogenous EPO production. HIF stabilization by oral administration of the HIF-PH inhibitor BAY 85-3934 (molidustat) resulted in dose-dependent production of EPO in healthy Wistar rats and cynomolgus monkeys. In repeat oral dosing of BAY 85-3934, hemoglobin levels were increased compared with animals that received vehicle, while endogenous EPO remained within the normal physiological range. BAY 85-3934 therapy was also effective in the treatment of renal anemia in rats with impaired kidney function and, unlike treatment with rhEPO, resulted in normalization of hypertensive blood pressure in a rat model of CKD. Notably, unlike treatment with the antihypertensive enalapril, the blood pressure normalization was achieved without a compensatory activation of the renin-angiotensin system. Thus, BAY 85-3934 may provide an approach to the treatment of anemia in patients with CKD, without the increased risk of adverse cardiovascular effects seen for patients treated with rhEPO. Clinical studies are ongoing to investigate the effects of BAY 85-3934 therapy in patients with renal anemia.

Penetration of moxifloxacin into rat mandibular bone and soft tissue.

OBJECTIVE: Based on its in vitro activity and spectrum of activity, the new 8-methoxyquinolone antibiotic moxifloxacin (MXF) seems suited for the antibiotic therapy of odontogenic infections. Penetration into the relevant tissue is another prerequisite for clinical efficacy. For this reason, the levels of MXF in plasma, soft tissue, and mandibular bone were determined in an animal model with Wistar rats. MATERIAL AND METHODS: Samples of 49 rats were analyzed. Tissue samples were homogenized and proteins were precipitated. The pharmacokinetic evaluation was conducted based on non-compartmental analysis. RESULTS: The concentration-time courses of tissues show a more plateau-shaped curve compared to plasma. Calculated AUC (area under the curve) ratios tissue:plasma were M. masseter:plasma = 2.64 and mandibles:plasma = 1.13. CONCLUSIONS: Administration of antibiotics is considered an important part of therapy during and/or after surgical procedures in the maxillofacial area. Because of the good penetration into bone and muscle tissues demonstrated in Wistar rats, MXF might be an option for clinical application in this indication.

Effects of enteral feeding on the oral bioavailability of moxifloxacin in healthy volunteers.

BACKGROUND AND OBJECTIVE: Moxifloxacin is a new generation fluoroquinolone antimicrobial agent used worldwide. In clinical practice in intensive care units, moxifloxacin may be frequently administered through a nasogastric feeding tube. In the absence of an oral liquid formulation and since the multivalent cations contained in enteral feeds may potentially impair absorption of moxifloxacin administered via this route, we studied the effect of concomitant enteral feeding on the pharmacokinetics and tolerability of moxifloxacin administered as a crushed tablet through the nasogastric tube. PARTICIPANTS AND METHODS: This was a single-centre, open-label, randomised, controlled, nonblinded, three-way crossover study. Twelve young healthy volunteers (nine females and three males) aged 20-42 years were included in the study. Each participant received three separate treatment regimens in a randomised fashion: an intact moxifloxacin 400 mg tablet (regimen A, reference treatment), a crushed moxifloxacin 400 mg tablet as a suspension through a nasogastric tube with water (regimen B) and a crushed moxifloxacin 400 mg tablet as a suspension through a nasogastric tube with enteral feeding (regimen C). A washout period of 1-week followed each treatment. Concentrations of moxifloxacin in serum were measured by a validated high-performance liquid chromatography method. Pharmacokinetic parameters were calculated by noncompartmental methods. Additionally, the primary parameters indicative for changes in absorption (area under the serum concentration-time curve from time zero to infinity [AUC(infinity)] and peak serum concentration [C(max)]), were tested for bioequivalence, assuming log-normally distributed data using ANOVA. RESULTS: All moxifloxacin treatment regimens were well tolerated. The AUC(infinity) was slightly, but not statistically significantly, decreased in treatments with regimens B and C. AUC(infinity) (geometric means 39.6 [regimen A] vs 36.1 [regimen B] vs 36.1 mg.h/L [regimen C] and point estimates 91% for B : A and C : A) indicated bioequivalence of the treatments. Bioequivalence criteria of AUC(infinity) and C(max) were met upon retrospective statistical analysis. Likewise C(max) after moxifloxacin administration through nasogastric tube with water (regimen B) and with tube feed (regimen C) were slightly decreased (geometric means 3.20 [regimen A] vs 3.05 [regimen B] vs 2.83 mg/L [regimen C]; point estimates 88% for B : A, and 95% for C : A). They were within the range seen in other studies conducted with oral administration of the drug. No statistically significant differences were observed in time to reach C(max) (t(max); median 1.75 [regimen A] vs 1.00 [regimen B] vs 1.75 hours [regimen C]). Thus, the rate of absorption of moxifloxacin was not affected by administration through a nasogastric tube. This route of ingestion seems to be associated with a slight loss of bioavailability independent of the carrier medium used (water vs enteral feed); no clinically relevant interaction with the multivalent cations contained in the enteral feed was observed, indicating that moxifloxacin and enteral nutrition can be administered concomitantly. CONCLUSION: There was no clinically relevant effect of enteral feeding on the pharmacokinetics of oral moxifloxacin in healthy volunteers. This result has to be evaluated in patients, particularly those from the intensive care unit, who are characterised by severe infectious and/or concomitant diseases that might influence absorption of moxifloxacin.