A translational model-based approach to inform the choice of the dose in phase 1 oncology trials: the case study of erdafitinib.

PURPOSE: Erdafitinib (JNJ-42756493, BALVERSA) is a tyrosine kinase inhibitor indicated for the treatment of advanced urothelial carcinoma. In this work, a translational model-based approach to inform the choice of the doses in phase 1 trials is illustrated. METHODS: A pharmacokinetic (PK) model was developed to describe the time course of erdafitinib plasma concentrations in mice and rats. Data from multiple xenograft studies in mice and rats were analyzed using the Simeoni tumor growth inhibition (TGI) model. The model parameters were used to derive a range of erdafitinib exposures that might inform the choice of the doses in oncology phase 1 trials. Conversion of exposures to doses was based on preliminary PK assessments from the first-in human (FIH) study. RESULTS: A one-compartment PK disposition model, with linear absorption and dose-dependent clearance, adequately described the PK data in both mice and rats via an allometric scaling approach. The TGI model was able to describe tumor growth dynamics, providing quantitative measurements of erdafitinib antitumor potency in mice and rats. Based on these estimates, ranges of efficacious unbound concentration were identified for erdafitinib in mice (0.642-5.364 µg/L) and rats (0.782-2.565 µg/L). Based on the FIH data, it was possible to transpose exposures into doses and doses of above 4 mg/day provided erdafitinib exposures associated with significant TGI in animals. The findings were in agreement with the results of the FIH trial, in which the first hints of clinical activities were observed at 6 mg. CONCLUSION: The successful modeling exercise of erdafitinib preclinical data showed how translational PK-PD modeling might be a tool to help to inform the choice of the doses in FIH studies.

HPLC-UV determination of erdafitinib in mouse plasma and its application to pharmacokinetic studies.

Erdafitinib is a recently approved fibroblast growth factor receptor (FGFR) inhibitor. It is the first treatment targeting susceptible FGFR genetic alterations for patients with metastatic bladder cancer. A simple validated HPLC-UV method was developed for the determination of erdafitinib in mouse plasma. Erdafitinib and internal standard (rivaroxaban) were efficiently separated on Eclipse plus C18 column (4.6 × 100 mm, 3.5 µm). The mobile phase consisted of acetonitrile and 0.01 M ammonium acetate aqueous solution, adjusted to pH 4.4 with acetic acid (26:74, v/v) and it was eluted isocratically at a flow rate of 1.2 mL/min. The UV detection was at 292 nm and the total run time for each sample was 11 min. The method linearity was validated over the range of 0.05-2.00 µg/mL (r2 ≥ 0.9992) and the lower limit of quantification (LLOQ) was 0.05 µg/mL. The within-run and between-run accuracies were 98.56 and 99.24%, respectively while the CV of the method precision did not exceed 6.52%. Plasma samples were extracted using a solid phase extraction procedure and the extraction recoveries were 97.90 ± 4.58%. The method was optimized for the sensitive determination of the studied drug in mouse plasma and was successfully applied to its pharmacokinetic studies.

A Thorough QT Study of the Combination Glecaprevir + Pibrentasvir on Cardiac Repolarization in Healthy Subjects.

PURPOSE: Fixed-dose combination glecaprevir (GLE) 300 mg + pibrentasvir (PIB) 120 mg is an orally administered once daily antiviral regimen approved for the treatment of hepatitis C virus (HCV) infection. The objective of this study was to evaluate the potential for cardiac repolarization following GLE + PIB administration in healthy adults. METHODS: This placebo- and active-controlled, randomized, single-dose, 4-period, 4-sequence crossover study enrolled 48 healthy subjects. The doses of GLE 400 mg + PIB 120 mg were selected to provide exposures comparable to those with the doses that are therapeutic in the HCV-infected population, GLE 300 mg + PIB 120 mg. The doses of GLE 600 mg + PIB 240 mg were selected to provide supratherapeutic exposures without exceeding the exposures of the GLE + PIB maximal tolerated doses. Moxifloxacin 400 mg (active control/open label) was used for confirming the sensitivity of the ECG assay in detecting QTc prolongation. Time-matched plasma concentrations and triplicate ECGs were obtained on treatment days -1 and 1. The primary end point was time-matched, placebo-corrected, baseline-adjusted Fridericia-corrected QT interval (ΔΔQTcF). Pharmacokinetic-pharmacodynamic analyses characterized the relationship between GLE and PIB plasma concentrations and ΔΔQTcF using a linear regression model and linear mixed-effects model. Findings from categorical analyses of ECG-interval data were also summarized. Tolerability was evaluated through adverse-events monitoring, physical examination including vital sign measurements, ECGs, and laboratory tests. FINDINGS: A total of 48 subjects (22 women [46%], 26 men [54%]), were enrolled in the study, and 47 subjects completed all 4 periods. None of the subjects had a change from baseline in QTcF interval of >30 msec or an absolute QTcF interval of >450 msec. Peak ΔΔQTcF values observed at 5 h postdose (Tmax) were 2.9 msec (upper 95% confidence limit, 4.9 msec) with the therapeutic dose and 3.1 msec (upper 95% confidence limit, 5.1 msec) with the supratherapeutic dose, with both upper 95% confidence limits well below the 10-msec threshold. Assay sensitivity was confirmed by peak ΔΔQTcF in the positive control (12.8 ms at 2 h postdose). No statistically significant GLE or PIB concentration-dependent effects on ΔΔQTcF were observed. Headache and skin irritation from ECG electrodes were the most commonly reported AEs. No clinically significant vital sign measurements, ECG findings, or laboratory measurements were observed. There were no patterns of T- and U-wave morphologic abnormalities. IMPLICATIONS: The fixed-dose combination regimen of GLE/PIB does not prolong the QTc interval. ClinicalTrials.gov identifier.

Disposition of cyadox in domesticated cats following oral, intramuscular, and intravenous administration.

Cyadox (CYX) is a synthetic antibacterial agent of quinoxaline with much lower toxic effects. A safety criterion of CYX for clinical use was established by studying the pharmacokinetics and metabolism of CYX after oral (PO), intramuscular (IM), and intravenous (IV) administration. CYX was administered in six domesticated cats (three males and three females) by PO (40 mg/kg.b.w.), IM (10 mg/kg.b.w.), and IV (10 mg/kg.b.w.) routes in a crossover pattern. Highly sensitive liquid chromatography with ultraviolet detection (HPLC-UV) method was developed for detection of CYX and its metabolites present in plasma, urine, and feces. The bioavailability of CYX after PO and IM routes was 4.37% and 84.4%. The area under curves (AUC), mean resident time (MRT), and clearance (CL) of CYX and its metabolites revealed that CYX quickly metabolized into its metabolites. The total recovery of CYX and its main metabolites was >60% after each route. PO delivery suggesting first pass effect in cats that might make this route suitable for intestinal infection and IM injection could be better choice for systemic infections. Less ability of glucuronidation did not show any impact on CYX metabolism. The findings of present study provide detailed information for evaluation of CYX.

Accuracy of liver stiffness measurement and controlled attenuation parameter using FibroScan® M/XL probes to diagnose liver fibrosis and steatosis in patients with nonalcoholic fatty liver disease: a multicenter prospective study.

BACKGROUND: Few studies have evaluated both liver fibrosis and steatosis in patients with nonalcoholic fatty liver disease (NAFLD) using both FibroScan® M and XL probes. This study was performed to investigate the accuracy of both FibroScan® probes to diagnose liver fibrosis and steatosis in patients with NAFLD. METHODS: We prospectively enrolled 137 consecutive patients with clinically suspected NAFLD in our joint-research facilities. Liver biopsies, liver stiffness measurements (LSMs), and controlled attenuation parameter (CAP) measurements were performed, and 122 patients with NAFLD diagnosed pathologically by central pathologists were included in the final analysis. RESULTS: Reliable LSM results were obtained in 85.2% (M) and 89.3% (XL) of patients, and CAP was reliable in 90.2% (M) and 90.2% (XL). The median LSM was significantly lower with the XL than M probe, and CAP was significantly higher with the XL than M probe. The optimal cut-off values for diagnosing the fibrosis stage were lower for LSM with the XL than M probe (stage ≥ 2, 6.7 vs. 7.0; stage ≥ 3, 8.2 vs. 10.8; stage 4, 14.3 vs. 16.8, respectively), whereas those of CAP were higher for the XL than M probe (score of ≥ 2, 273 vs. 267; score of 3, 302 vs. 286, respectively). There were no significant differences in accuracy of the LSM and CAP between the probes. CONCLUSIONS: Liver fibrosis and steatosis could be equally evaluated with FibroScan® M and XL probes in patients with NAFLD. There was no significant difference in diagnostic accuracy between the two probes using probe-specific cut-off values.

Effect of Fluconazole and Itraconazole on the Pharmacokinetics of Erdafitinib in Healthy Adults: A Randomized, Open-Label, Drug-Drug Interaction Study.

BACKGROUND AND OBJECTIVES: Erdafitinib, an oral selective pan-fibroblast growth factor receptor (FGFR) kinase inhibitor, is primarily metabolized by cytochrome P450 (CYP) 2C9 and 3A4. The aim of this phase 1 study was to assess the pharmacokinetics and safety of erdafitinib in healthy participants when coadministered with fluconazole (moderate CYP2C9 and CYP3A inhibitor), and itraconazole (a strong CYP3A4 and P-glycoprotein inhibitor). The effect of CYP2C9 genotype variants (*1/*1, *1/*2, *1/*3) on the pharmacokinetics of erdafitinib was also investigated. METHODS: In this open-label, parallel-group, single-center study, eligible healthy adults were randomized by CYP2C9 genotype to receive Treatment A (single oral dose of erdafitinib 4 mg) on day 1, Treatment B (fluconazole 400 mg/day orally) on days 1-11, or Treatment C (itraconazole 200 mg/day orally) on days 1-11. Healthy adults randomized to Treatment B and C received a single oral 4-mg dose of erdafitinib on day 5. The pharmacokinetic parameters, including mean maximum plasma concentration (Cmax), area under the curve (AUC) from time 0 to 168 h (AUC168h), AUC from time 0 to the last quantifiable concentration (AUClast), and AUC from time 0 to infinity (AUC∞) were calculated from individual plasma concentration-time data using standard non-compartmental methods. RESULTS: Coadministration of erdafitinib with fluconazole increased Cmax of erdafitinib by approximately 21%, AUC168h by 38%, AUClast by 49%, and AUC∞ by 48% while coadministration with itraconazole resulted in no change in erdafitinib Cmax and increased AUC168h by 20%, AUClast by 33% and AUC∞ by 34%. Erdafitinib exposure was comparable between participants with CYP2C9 *1/*2 or *1/*3 and with wild-type CYP2C9 genotype. The ratio of total amount of erdafitinib excreted in the urine (inhibited to non-inhibited) was 1.09, the ratio of total amount of excreted metabolite M6 was 1.21, and the ratio of the metabolite to parent ratio in the urine was 1.11, when coadministration of erdafitinib with itraconazole was compared with single-dose erdafitinib. Treatment-emergent adverse events (TEAEs) were generally Grade 1 or 2 in severity; the most commonly reported TEAE was headache. No safety concerns were identified with single-dose erdafitinib when administered alone and in combination with fluconazole or itraconazole in healthy adults. CONCLUSION: Coadministration of fluconazole or itraconazole or other moderate/strong CYP2C9 or CYP3A4 inhibitors may increase exposure to erdafitinib in healthy adults and thus may warrant erdafitinib dose reduction or use of alternative concomitant medications with no or minimal CYP2C9 or CYP3A4 inhibition potential. TRIAL REGISTRATION: ClinicalTrials.gov identifier number: NCT03135106.

Population Pharmacokinetics of Total and Free Erdafitinib in Adult Healthy Volunteers and Cancer Patients: Analysis of Phase 1 and Phase 2 Studies.

A population pharmacokinetic (PK) model was developed using data pooled from 6 clinical studies (3 in healthy volunteers and 3 in cancer patients) to characterize total and free plasma concentrations of erdafitinib following single- and multiple-dose administration, to understand clinically relevant covariates, and to quantify the inter- and intraindividual variability in erdafitinib PK. An open, linear, 3-compartment disposition model with first-order absorption and a lag time was used to describe the PK profile of total and free erdafitinib plasma concentrations. The PK of erdafitinib were linear and time independent. After oral administration, erdafitinib was rapidly absorbed, with a time to maximum concentration between 2 and 4 hours. In patients, erdafitinib total apparent oral clearance was 0.200 L/h (median free fraction = 0.24%), and the effective terminal half-life of total drug was 76.4 hours. Interindividual variability in PK parameters was moderate for oral clearance and central volume of distribution, and large for absorption rate and peripheral volume of distribution. Sex and renal function were significant covariates on free oral clearance, while weight, sex, and α1 -acid-glycoprotein were significant on oral central volume of distribution. Age, race, and mild hepatic impairment were not significant covariates of erdafitinib exposure. Given that the magnitude of the covariate effects were within 25% of reference values and that the recommended dosing regimen of erdafitinib comprises individual dose up-titrations and reductions based on presence or absence of toxicities, the clinical relevance of the investigated covariates is expected to be limited, and no dose adjustments are warranted.

Effect of Plasma Protein Binding on the Pharmacokinetics of Erdafitinib: Results of an Integrated Cross-Study Analysis.

Erdafitinib, a potent oral fibroblast growth factor receptor inhibitor, is a low extraction ratio drug highly bound to alpha-1-acid glycoprotein (AGP) with free fraction (fu ) varying across populations. This analysis aimed to characterize the impact of plasma protein binding on erdafitinib pharmacokinetics (PK). Plasma protein-binding data (fu , AGP, albumin) and PK parameters were pooled from 6 phase 1 studies in healthy participants and 1 first-in-human study in patients with cancer. Binding kinetics were characterized using a nonlinear mixed-effects model. Mean (coefficient of variation, CV%) fu was 0.510% (39.4%) for healthy participants and 0.316% (64.0%) for patients, with a 2.1-fold higher AGP and 10% lower albumin. Linear binding of erdafitinib to AGP and albumin was observed, with >1000-fold higher binding constant for AGP than albumin (17.6 vs 0.017 µM-1 ). The fu decreased with increasing AGP in a nonlinear relationship. Despite its abundance in plasma relative to AGP, albumin contributed to <4% of the overall binding of erdafitinib (1.8% in patients; 4.0% in healthy participants). The AGP-binding constant was 68.0% lower in predose (spiked) versus postdose (ex vivo) samples. Total oral clearance was generally proportional to the fu and higher in healthy participants than in patients, consistent with the differences in AGP. Correcting for fu accounted for the majority of the relationship between oral clearance and fu as expected with a low extraction ratio drug. Characterizing free erdafitinib concentrations is critical to accounting for differences in fu and to further investigating its clinical relevance.

The pharmacogenetics of OATP1B1 variants and their impact on the pharmacokinetics and efficacy of elbasvir/grazoprevir.

Aim: To evaluate the effect of SLCO1B1 genetic variants on grazoprevir pharmacokinetics and efficacy. Methods: A retrospective analysis of 1578 hepatitis C virus-infected participants from ten Phase II/III clinical trials. Results: Relative to noncarriers of the risk allele, geometric mean ratios (95% CI) of grazoprevir area under curve (AUC)0-24 were: rs4149056 (risk allele C), one copy, 1.13 (1.06-1.21), two copies, 1.43 (1.16-1.77); and rs11045819 (risk allele A), one copy, 0.93 (0.87-1.00); two copies, 0.78 (0.61-1.00). The rs2306283 variant was not associated with grazoprevir exposure. None of the SLCO1B1 variants were associated with sustained virologic response. Conclusion: Genetic variants in SLCO1B1 were associated with modest changes in grazoprevir pharmacokinetics, but not with meaningful differences in efficacy.

Pharmacokinetics of elbasvir and grazoprevir in subjects with end-stage renal disease or severe renal impairment.

PURPOSE: To describe the phase 1 and population pharmacokinetic investigations that support dosing recommendations for elbasvir/grazoprevir (EBR/GZR) in hepatitis C virus-infected people with advanced chronic kidney disease. METHODS: This was an open-label, two-part, multiple-dose trial (MK-5172 PN050; NCT01937975) in 24 non-HCV-infected participants with end-stage renal disease (ESRD) or severe renal impairment who received once-daily EBR 50 mg and GZR 100 mg for 10 days. Population pharmacokinetic analyses from the phase 3 C-SURFER study (PN052, NCT02092350) were also conducted. RESULTS: When comparing haemodialysis (HD) and non-HD days in participants with ESRD, geometric mean ratios (GMRs) (90% confidence intervals [CIs]) for EBR and GZR AUC0-24 were 1.14 (1.08-1.21) and 0.97 (0.87-1.09). When comparing ESRD and healthy participants, GMRs (90% CIs) for EBR and GZR AUC0-24 were 0.99 (0.75-1.30) and 0.83 (0.56-1.22) on HD days, and 0.86 (0.65-1.14) and 0.85 (0.58-1.25) on non-HD days. GMRs (90% CIs) for AUC0-24 in participants with severe renal impairment relative to healthy controls were 1.65 (1.09-2.49) for GZR and 1.86 (1.38-2.51) for EBR. In population modelling of data from C-SURFER, absolute geometric means of steady-state EBR AUC0-24 were 2.78 and 3.07 µM*h (HD and non-HD recipients) and GZR AUC0-24 were 1.80 and 2.34 µM*h (HD and non-HD recipients). CONCLUSIONS: EBR/GZR represents an important treatment option for HCV infection in people with severe renal impairment and those with ESRD. No dosage adjustment of EBR/GZR is required in people with any degree of renal impairment, including those receiving dialysis.

A Phase 1 Study to Evaluate the Effect of Crushing, Cutting Into Half, or Grinding of Glecaprevir/Pibrentasvir Tablets on Exposures in Healthy Subjects.

Glecaprevir (GLE) and pibrentasvir (PIB) are direct-acting antivirals coformulated as a combination tablet for once-daily treatment of chronic hepatitis C virus infection. The objective of this study was to evaluate the effect of different methods of tablet manipulations-cutting in half, grinding into powder, or crushing-on the bioavailability of GLE and PIB relative to whole film-coated bilayer tablets. This was a phase 1, single-dose, open-label, randomized, 5-period, nonfasting crossover study in 25 healthy adult male and female subjects. Intensive pharmacokinetic measurements were carried out up to 48 h after dosing on day 1 of each period. Safety and tolerability was assessed throughout the study. Compared with the reference whole tablets, cutting into half had minimal impact on GLE and PIB exposures (≤15% difference), whereas grinding or crushing the tablets resulted in lower exposures (27% to 61%) for GLE and higher exposures (21% to 83%) for PIB. These results provide guidance on appropriate administration of GLE/PIB in patients who have difficulty swallowing whole tablets.

A phase I dose-escalation study of the safety and pharmacokinetics of a tablet formulation of voxtalisib, a phosphoinositide 3-kinase inhibitor, in patients with solid tumors.

Background Voxtalisib, a PI3K/mTOR inhibitor, has shown antitumor activity in capsule formulation in patients with solid tumors. This Phase I study assessed safety and pharmacokinetics of voxtalisib administered as immediate-release tablets in patients with solid tumors (NCT01596270). Methods A "3 + 3" dose escalation design was used. Adverse events (AEs), pharmacokinetics (PK), food effect and tumor response were evaluated. Results Thirty-two patients received voxtalisib doses ranging from 50 mg to 70 mg once daily (QD) and 17 patients received voxtalisib doses ranging from 30 mg to 50 mg twice daily (BID), for two 28-day cycles. Dose-limiting toxicities (DLTs) were Grade 3 fatigue (two patients at 70 mg QD, one patient at 40 mg BID) and Grade 3 rash (two patients at 50 mg BID). The maximum tolerated dose (MTD) was 60 mg for QD and 40 mg for BID regimens. Common treatment-emergent AEs were diarrhea (41%), nausea (37%) and fatigue (33%). Voxtalisib appeared to follow linear PK, with a general increase in plasma exposure with dose and no significant accumulation. Administration with food caused a slight decrease in exposure; however, given the high variability observed in the exposure parameters, this should be interpreted with caution. Best response was stable disease in 29% and 50% of patients (QD and BID regimens, respectively). Conclusions The safety profile of voxtalisib tablets at the MTD in patients with solid tumors was consistent with that observed with voxtalisib capsules. Given the limited activity observed across multiple clinical trials, no further trials of voxtalisib are planned.

Efficacy and safety of glecaprevir/pibrentasvir in Japanese patients with chronic genotype 1 hepatitis C virus infection with and without cirrhosis.

BACKGROUND: The once-daily, all oral, RBV-free, pangenotypic direct-acting anti-viral regimen consisting of co-formulated NS3/4A protease inhibitor glecaprevir and NS5A inhibitor pibrentasvir (G/P), demonstrated high rates of sustained virologic response (SVR) in phase 2 and 3 studies outside Japan. METHODS: CERTAIN-1 is a phase 3, open-label, multicenter study assessing the safety and efficacy of G/P (300/120 mg) once daily in Japanese patients with chronic HCV GT1 infection. Patients without cirrhosis received 8 weeks of G/P or 12 weeks of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r, 25/150/100 mg); patients with cirrhosis received G/P for 12 weeks. The primary efficacy endpoint was non-inferiority of G/P compared to OBV/PTV/r by assessing SVR at post-treatment week 12 (SVR12) among non-cirrhotic patients without the NS5A Y93H polymorphism. RESULTS: SVR12 was achieved by 128/129 (99.2%; one patient lost to follow-up) non-cirrhotic patients in the 8-week G/P Arm (including 23/23 patients with the NS5A Y93H polymorphism) and 52/52 (100%) patients in the 12-week OBV/PTV/r Arm. No patients from the G/P Arm prematurely discontinued the study drug or experienced a treatment-emergent serious adverse event (TESAE). Three patients from the OBV/PTV/r Arm experienced five TESAEs and one of these patients discontinued the study drug due to TESAEs. All 38 (100%) patients with compensated cirrhosis achieved SVR12; in this group, no TESAEs were reported and one patient discontinued treatment due to an AE. CONCLUSIONS: CERTAIN-1 study results demonstrate high efficacy and favorable tolerability of G/P in GT1-infected Japanese patients including those with the NS5A Y93H polymorphism, with no virologic failures observed.

Effects of Renal Impairment and Hemodialysis on the Pharmacokinetics and Safety of the Glecaprevir and Pibrentasvir Combination in Hepatitis C Virus-Negative Subjects.

Hepatitis C virus (HCV) infection is an independent risk factor for developing chronic renal impairment and end-stage renal disease. Limited treatment options are available for HCV genotype 2, 3, 5, and 6 infections in patients with an estimated glomerular filtration rate (eGFR) of <30 ml/min. Glecaprevir and pibrentasvir are active against all six major HCV genotypes, are primarily excreted in the bile, and have minimal renal elimination. Therefore, combined treatment with these direct-acting antivirals may be useful for patients with HCV infection and chronic kidney disease. A phase 1, multicenter, open-label study evaluated the effects of renal impairment on the pharmacokinetics and safety of glecaprevir-pibrentasvir. In substudy 1, 38 subjects with stage 2 to 5 chronic kidney disease who were not on dialysis or who had normal renal function received single doses of the combination of 300 mg glecaprevir and 120 mg pibrentasvir. In substudy 2, 8 subjects requiring hemodialysis received single doses of the combination of 300 mg glecaprevir and 120 mg pibrentasvir under dialysis and nondialysis conditions. Regression analyses demonstrated increased glecaprevir and pibrentasvir plasma exposures, as determined by the area under the curve, with decreasing renal function, up to 56% and 46%, respectively, in subjects with an eGFR of <15 ml/min/1.73 m2 In dialysis-dependent subjects, glecaprevir and pibrentasvir exposures were similar (≤18% difference) when study drugs were administered before hemodialysis or on a nondialysis day. Adverse events were mostly mild, with the most common being self-limited fatigue (3 subjects). The study findings support the clinical evaluation of glecaprevir-pibrentasvir without dose adjustment in HCV-infected subjects with renal impairment. (This study has been registered at ClinicalTrials.gov under registration number NCT02442258.).

Liquid chromatography-electrospray ionization-tandem mass spectrometry method for quantitative estimation of new imiqualine leads with potent anticancer activities in rat and mouse plasma. Application to a pharmacokinetic study in mice.

Imidazoquinoxaline derivatives (imiqualines) are a new series of anticancer compounds. Two lead compounds (EAPB0203 and EAPB0503) with remarkable in vitro and in vivo activity on melanoma and T-cell lymphomas have been previously identified. The modulation of the chemical structure of the most active compound, EAPB0503, has led to the synthesis of two compounds, EAPB02302 and EAPB02303, 7 and 40 times more active than EAPB0503 against A375 human melanoma cancer cell line, respectively. The aim of this study was to develop and validate a sensitive and accurate liquid chromatography-electrospray ionization-tandem mass spectrometry method to simultaneously quantify EAPB02303 and its potential active metabolite, EAPB02302, in rat and mouse plasma. Analytes were detected in multiple reaction monitoring acquisition mode using an electrospray ionization detector in positive ion mode. Following a liquid-liquid extraction with ethyl acetate, analytes and internal standard were separated by HPLC reversed-phase on a C18 RP18 Nucleoshell column (2.7µm, 4.6×100mm). The method was validated according to FDA and EMA Bioanalytical Method Validation guidelines. The robustness of the method was assessed by introducing small variations in nine nominal analytical parameters. Statistical interpretation was performed by mean of the Student's t-test. Standard curves were generated via unweighted quadratic regression of calibrators (EAPB02303: 1.95-1000ng/mL, EAPB02302: 7.81-1000ng/mL in rat plasma; EAPB02303: 0.98-1000ng/mL, EAPB02302: 1.95-1000ng/mL in mouse plasma). From the analysis of QC samples, intra- and inter-assay precision and accuracy studies demonstrated %R.S.Ds. <12.5% and percent deviation from nominal concentration <7%. Matrix effects (mean matrix factors from 91.8-108.5% in rat plasma; and from 90.4-102.4% in mouse plasma) and stability assays (recoveries >87%) were acceptable and in accordance with the guidelines. No quantifiable carryover effect was observed. The LLOQs were 1.95ng/mL for EAPB02303 and 7.81ng/mL for EAPB02302 in rat plasma, and 0.98ng/mL and 1.95ng/mL for the two compounds in mouse plasma, respectively. This method was successfully implemented to support a mouse pharmacokinetic study following a single intraperitoneal administration of EAPB02303 in male C57Bl/6 mice. The obtained pharmacokinetic parameters of EAPB02303 would be useful to optimize the dosing and the rhythm of administration for subsequent preclinical in vivo activity studies.

Pharmacokinetic Interactions and Safety of Coadministration of Glecaprevir and Pibrentasvir in Healthy Volunteers.

BACKGROUND AND OBJECTIVE: Glecaprevir and pibrentasvir are pangenotypic direct-acting antiviral agents for the treatment of chronic hepatitis C virus infection. The aim of the present study was to evaluate the drug-drug interaction and safety of glecaprevir and pibrentasvir coadministration in healthy volunteers. METHODS: In this open-label, randomized, multiple-dose, Phase 1 study in 72 subjects, glecaprevir (100-1200 mg once daily) and pibrentasvir (40-200 mg once daily) were administered alone for 7 days and then in combination for another 7 days. Intensive blood sampling was performed on Days 1, 7, 8, and 14, and pharmacokinetic interactions were assessed using a repeated measures analysis of glecaprevir and pibrentasvir maximum plasma concentration (C max) and area under the curve (AUC). RESULTS: Coadministration of glecaprevir 400 mg increased pibrentasvir 120 and 40 mg steady-state C max and AUC values to 2.9-6.3-fold, and coadministration of glecaprevir 700 mg increased pibrentasvir 160 mg steady-state C max and AUC24 values to up to sevenfold of the values when pibrentasvir was administered alone. Glecaprevir C max and AUC values during coadministration were less than 1.5-fold of the values when glecaprevir was administered alone. The combination of glecaprevir and pibrentasvir at doses up to 400 mg was well tolerated by the healthy subjects in this study. High glecaprevir exposures at 700 and 1200 mg were associated with grade 2/3 elevations in alanine aminotransferase, aspartate aminotransferase, and/or bilirubin. CONCLUSIONS: Coadministration of pibrentasvir 120 mg with glecaprevir doses up to 400 mg resulted in increases in pibrentasvir exposures without significant changes in glecaprevir exposures in the absence of any clinically significant laboratory abnormalities.

Plasma pharmacokinetics of quinocetone in ducks after oral and intravenous administration.

Quinocetone (QCT), an antimicrobial growth promoter, is widely used in food-producing animals. However, information about pharmacokinetics (PK) of QCT in ducks still remains unavailable up to now. In this study, QCT and its major metabolites (1-desoxyquinocetone, di-desoxyquinocetone and 3-methyl-quinoxaline-2-carboxylic) in ducks were studied using a simple and sensitive UHPLC-MS/MS assay. Twenty ducks were divided into two groups. (n = 10/group). One group received QCT by oral administration at dose of 40 mg/kg while another group received QCT intravenously at 10 mg/kg. Plasma samples were collected at various time points from 0 to 96 hr. QCT and its major metabolites in duck plasma samples were extracted by 1 ml acetonitrile and detected by UHPLC-MS/MS, with the gradient mobile phase that consisted of 0.1% formic acid in water (A) and acetonitrile (B). A noncompartment analysis was used to calculate the PK parameters. The results showed that following oral dosing, the peak plasma concentration (Cmax ) of QCT was 32.14 ng/ml and the area under the curve (AUCINF_obs) was 233.63 (h ng)/ ml. Following intravenous dosing, the Cmax , AUCINF_obs and Vss_obs were 96.70 ng/ml, 152.34 (h ng)/ ml and 807.00 L/kg, respectively. These data indicated that the QCT was less absorbed in vivo following oral administration, with low bioavailability (38.43%). QCT and its major metabolites such as 1-desoxyquinocetone and 3-methyl-quinoxaline-2-carboxylic were detected at individual time points in individual ducks, while the di-desoxyquinocetone was not detected in all time points in all ducks. This study enriches basic scientific data about pharmacokinetics of QCT in ducks after oral and intravenous administration and will be beneficial for clinical application in ducks.

No Pharmacokinetic Interaction Between the Hepatitis C Virus Inhibitors Elbasvir/Grazoprevir and Famotidine or Pantoprazole.

Use of agents to suppress gastric acid secretion is common among patients with hepatitis C virus (HCV) infection. The aims of this open-label, three-period, fixed-sequence study were to evaluate the effect of famotidine and pantoprazole on the pharmacokinetics and safety of elbasvir/grazoprevir fixed-dose combination (FDC) in 16 healthy subjects. Elbasvir and grazoprevir each exhibited similar pharmacokinetics following single-dose administration of elbasvir/grazoprevir with or without famotidine or pantoprazole. Geometric mean ratios (GMRs) of grazoprevir AUC(0,∞), Cmax , and C24 (elbasvir/grazoprevir + famotidine or elbasvir/grazoprevir + pantoprazole vs. elbasvir/grazoprevir) ranged from 0.89-1.17. Similarly, GMRs of elbasvir AUC(0,∞), Cmax , and C24 (elbasvir/grazoprevir + famotidine or elbasvir/grazoprevir + pantoprazole vs. elbasvir/grazoprevir) ranged from 1.02-1.11. These results indicate that gastric acid-reducing agents do not modify the pharmacokinetics of elbasvir or grazoprevir in a clinically relevant manner and may be coadministered with elbasvir/grazoprevir in HCV-infected patients without restriction.

The combination of elbasvir and grazoprevir for the treatment of chronic HCV infection in Japanese patients: a randomized phase II/III study.

BACKGROUND: Elbasvir (EBR) in combination with grazoprevir (GZR) has demonstrated efficacy in patients with hepatitis C virus (HCV) infections in trials primarily conducted in the USA and Europe. We investigated the safety and efficacy of EBR in combination with GZR in Japanese patients with chronic HCV infection, with or without cirrhosis. METHODS: The study was conducted in two parts. In part 1, noncirrhotic patients were randomized 1:1 to receive EBR (50 mg) in combination with GZR (50 or 100 mg) once daily for 12 weeks. In part 2, noncirrhotic patients were randomized 3:1 to receive immediate or deferred treatment with EBR (50 mg) and GZR (100 mg, determined in part 1) for 12 weeks; cirrhotic patients received open-label immediate treatment. The primary efficacy end point was the rate of sustained virologic response 12 weeks after completion of the study treatment. RESULTS: In part 1, 63 patients were randomized to receive EBR in combination with GZR at a dose of 50 mg (n = 31) or 100 mg (n = 32). The SVR12 rates were 100% with GZR at a dose of 50 mg and 96.8% with GZR at a dose of 100 mg. Tolerability was similar in both arms. In part 2, 301 noncirrhotic patients were randomized to receive immediate treatment (n = 227) or deferred treatment (n = 74), and 35 cirrhotic patients were enrolled. The SVR12 rates were 96.5% and 97.1% after immediate treatment in noncirrhotic and cirrhotic patients respectively. Safety was generally similar between immediate and deferred treatment. CONCLUSION: Treatment with EBR in combination with GZR for 12 weeks is effective and well tolerated in Japanese patients with chronic HCV infection. CLINICALTRIALS. GOV IDENTIFIER: NCT02203149.