Drug-drug interaction of ciprofol injectable emulsion with mefenamic acid capsules in healthy subjects.

AIMS: To investigate the drug-drug interaction (DDI) of ciprofol injectable emulsion and mefenamic acid capsules in healthy subjects. METHODS: Twenty healthy subjects were enrolled in this single-centre, open-label, two-period DDI study. Ciprofol (0.4 mg kg-1 ) was administered as a single dose on days 1 and 5. A 500-mg oral loading dose of mefenamic acid was given on day 4 followed by a 250-mg maintenance dose every 6 h (a total of eight doses). Blood samples for pharmacokinetic analyses were collected. Depth of anaesthesia was monitored using the Modified Observer's Assessment of Alertness and Sedation (MOAA/S) scale and Bispectral Index scores (BISs). RESULTS: Compared with administration of ciprofol alone, administration with mefenamic acid showed no significant difference in exposure. The geometric mean ratios (GMRs) and their 90% confidence intervals (CIs) for maximum plasma concentration (Cmax ), area under the plasma concentration-time curve calculated from 0 to the last measurement point (AUC0-last ) and AUC to infinity (AUC0-inf ) were 91.6% (86.5-96.9%), 103.3% (100.3-106.4%) and 107.0% (101.2-113.2%), respectively. The MOAA/S and BIS curves for the two treatment periods essentially coincided, indicating that the anaesthesia effect of ciprofol was not affected by mefenamic acid. Seven subjects (35%) reported eight adverse events (AEs) when ciprorol was administered alone and 12 subjects (60%) reported 18 AEs when ciprofol was administered in combination with mefenamic acid. All AEs were mild. CONCLUSIONS: Mefenamic acid, a UGT1A9 inhibitor, had no significant effect on the pharmacokinetics and pharmacodynamics of ciprofol in healthy subjects. Ciprofol was safe and well tolerated when administered with mefenamic acid.

Population pharmacokinetics and enterohepatic recirculation of hyzetimibe and its main metabolite in Chinese healthy subjects.

AIMS: Hyzetimibe (HS-25), a new drug approved for hypercholesterolaemia, exhibits obvious enterohepatic recirculation (EHC) after oral administration. Up to now, little is known about the kinetics of HS-25. Therefore, we performed this population pharmacokinetic (PopPK) analysis aiming to describe the PK behaviour of HS-25 and its main metabolite (M1), and to identify significant covariates contributing to the variability. METHODS: The plasma concentration data used for modelling were obtained from an open-label, single-dose, randomized, 2-period crossover bioequivalence study. PopPK modelling was performed with NONMEM 7.4.1 using nonlinear mixed effect modelling approach. Goodness of fit plots, bootstrap and visual predictive check were used for model internal validation. Data from another study were used for external validation. RESULTS: Data from 16 male and 8 female subjects were used in the PopPK analysis. HS-25 and M1 concentrations in the modelling cohort were well described by a 1-compartment model incorporating first-pass metabolism and a gallbladder compartment, accounting for the EHC process. The release kinetic of gall was mimicked by a first-order constant plus a switch on/off effect. Body weight was identified as a significant covariate effecting on the clearance and apparent distribution volume of HS-25, as well as kmg , the transfer rate from metabolite compartment to gallbladder compartment. Internal and external validation demonstrated an acceptable predictive ability of the final model. CONCLUSION: We present the first PopPK model describing HS-25 and M1 concentrations simultaneously, with the EHC process considered. The modelling and simulation results could provide reference for the clinical use of HS-25.

Effects of food on the pharmacokinetics of ensartinib in healthy Chinese subjects.

Ensartinib is a promising, aminopyridazine-based small molecule that potently inhibits anaplastic lymphoma kinase. This random, two-period, crossover study evaluated the effects of food on the pharmacokinetics of ensartinib after a single dose (225 mg) in healthy Chinese subjects. The pharmacokinetic parameters of ensartinib were calculated using non-compartmental analysis. Twenty-four healthy Chinese subjects age 20-44 years were included in this study. The area under the concentration-time curve of ensartinib was ~25% lower after the intake of a high-fat, high-calorie meal before dosing, whereas the maximum plasma concentration was decreased by ~37%, illustrating the statistically significant effect of food on ensartinib pharmacokinetics. In addition, food intake prolonged the absorption phase of ensartinib (median time to maximum plasma concentration, from 4.5 to 6 hours). Population pharmacokinetic (PopPK) analysis was conducted using NONMEM, and the influences of food, age, sex, body weight and body mass index were studied via covariate analysis. In this analysis, ensartinib plasma concentrations were best described by a one-compartment model with Weibull absorption. The final model included food and age as covariates on apparent distribution and apparent clearance. Based on the final PopPK model, food was identified as a significant covariate for apparent clearance, apparent volume of distribution and absorption rate constant, consistent with the results of non-compartmental pharmacokinetic analysis.

Simulation of febuxostat pharmacokinetics in healthy subjects and patients with impaired kidney function using physiologically based pharmacokinetic modeling.

Febuxostat is recommended by the American College of Rheumatology Gout Management Guidelines as a first-line therapy for lowering the level of urate in patients with gout. At present, this drug is being prescribed mainly based on the clinical experience of doctors. The potential effects of clinical and demographic variables on the bioavailability and therapeutic effectiveness of febuxostat are not being considered. In this study a physiologically based pharmacokinetic (PBPK) model of febuxostat was developed, thereby providing a theoretical basis for the individualized dosing of this drug in gout patients. The plasma concentration-time profiles corresponding to healthy subjects and gout patients with normal kidney function were simulated and validated; then, the model was used to predict the pharmacokinetic (PK) data of the drug in gout patients suffering from varying degrees of impaired kidney function. The error values (the predicted value/observed value) were used to validate the simulated PK parameters predicted by the PBPK model, including the area under the plasma concentration-time curve, the maximum plasma concentration, and time to maximum plasma concentration. Considering that to all error fold changes were smaller than 2, the PBPK model was. In subjects suffering from mild kidney impairment, moderate kidney impairment, severe kidney impairment, and endstage kidney disease (ESRD), the predicted AUC0-24h values increased by 1.62, 1.74, 2.27, and 2.65-fold, respectively, compared to gout patients with normal kidney function. Overall, the results showed that the PBPK model constructed in this study predict the pharmacokinetic changes in gout patients suffering from varying degrees of impaired kidney function.

Development of LC-MS/MS determination method and backpropagation artificial neural networks pharmacokinetic model of febuxostat in healthy subjects.

WHAT IS KNOWN AND OBJECTIVE: Febuxostat is a well-known drug for treating hyperuricemia and gout. The published methods for determination of febuxostat in human plasma might be unsuitable for high-throughput determination and widespread application. We need to develop a highly selective, sensitive and rapid liquid chromatography-tandem mass spectrometry method. METHODS: The chromatographic separation was achieved on a Hypersil Gold-C18 (2.1 mm × 100 mm, 1.9 µm) column with mobile phase A (Water containing 0.1% formic acid) and mobile phase B (acetonitrile containing 0.1% formic acid). Multiple reaction monitoring (MRM) mode was used for quantification using target ions at m/z 315.3 â†’ m/z 271.3 for febuxostat and m/z 324.3 â†’ m/z 280.3 for Febuxostat-d9 (IS). A backpropagation artificial neural network (BPANN) pharmacokinetic model was constructed by the data of bioequivalence study. RESULTS AND DISCUSSION: After the LC-MS/MS method validated, it was successfully applied to the bioequivalence study of 30 human volunteers under fed condition. The predicted concentrations generated by BPANN model had a high correlation coefficient with experimental values. WHAT IS NEW AND CONCLUSION: A sensitive LC-MS/MS method had been developed and validated for determination of febuxostat in healthy subjects under fed condition, and a BPANN model was developed that can be used to predict the plasma concentration of febuxostat.

A new simple method for quantification of cilostazol and its active metabolite in human plasma by LC-MS/MS: Application to pharmacokinetics of cilostazol associated with CYP genotypes in healthy Chinese population.

A simple, sensitive, and fully automated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of cilostazol (CIL) and its active metabolite, 3,4-dehydro cilostazol (CIL-M), in human plasma. Plasma samples were processed by protein precipitation in 2 mL 96-deep-well plates, and all liquid transfer steps were performed through robotic liquid handling workstation, enabling the whole procedure fast, compared to the reported methods. Separation of analytes was successfully achieved on a UPLC BEH C18 column (2.1 × 100 mm, 1.7 µm) with mobile phase A (5 mM ammonium formate containing 0.1% formic acid) and mobile phase B (methanol) at a flow rate of 0.30 mL min-1 . The total run time was 3.5 min per sample. Mass spectrometric detection was conducted by electrospray ion source in positive ion multiple reaction monitoring mode. Calibration curves were linear over the concentration range of 1.0-800 ng·mL-1 for CIL and 0.05-400 ng·mL-1 for CIL-M. The coefficient of variation for the assay's precision was 12.3%, and the accuracy was 88.8-99.8%. It was fully validated and successfully applied to assess the influence of CYP genotypes on the pharmacokinetics of CIL after oral administration of 50 mg tablet formulations of CIL to healthy Chinese volunteers. The results suggest that, in Chinese population, the genotype of CYP3A5 affects the plasma exposure of CIL.

Non-small cell lung cancer cells with deficiencies in homologous recombination genes are sensitive to PARP inhibitors.

Lung cancer is the leading cause of cancer death worldwide. PARP inhibitors have become a new line of cancer therapy and a successful demonstration of the synthetic lethality concept. The mechanism and efficacy of PARP inhibitors have been well studied in some cancers, especially homologous recombination (HR)-deficient ovarian cancer and breast cancer, yet such studies are still relatively fewer in lung cancer. Here we found that HR genes are frequently mutated in lung cancer patients, exposing a window for targeted therapies by PARP inhibitors. We depleted BRCA1 and BRCA2 in non-small cell lung cancer (NSCLC) cancer cells and found these cells are hypersensitive to the PARP inhibitor olaparib in cell viability and clonogenic survival assays. Olaparib specifically induces apoptosis in A549 cells with BRCA1 or BRCA2 depletion, as determined by positive Annexin-V staining. In addition, we show that A549 cells with ATM shRNA knockdown are also hypersensitive to Olaparib. In summary, our data support the potential use of PARP inhibitors in NSCLC with HR deficiency.

Determination of tigecycline in human plasma by LC-MS/MS and its application to population pharmacokinetics study in Chinese patients with hospital-acquired pneumonia.

A selective, sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of tigecycline (TGC) in human plasma, using tigecycline-d9 as an internal standard (IS). Analytical samples were prepared using a protein precipitation method coupled with a concentration process. The analyte and IS were separated on a reversed-phase Waters Acquity UPLC® BEH-C18 column (2.1 × 50 mm i.d., 1.7 µm) with a flow rate of 0.25 mL/min. The mobile phase consisted of water, containing 0.2% formic acid (v/v) with 10 mm ammonium formate (A) and acetonitrile (B). The mass spectrometer was operated in selected reaction monitoring mode through electrospray ionization ion mode using the transitions of m/z 586.2 → 513.1 and m/z 595.1 → 514.0 for TGC and IS, respectively. The linearity of the method was in the range of 10-5000 ng/mL. Intra- and inter-batch precision (CV) for TGC was <9.27%, and the accuracy ranged from 90.06 to 107.13%. This method was successfully applied to the analysis of samples from hospital-acquired pneumonia patients treated with TGC, and a validated population pharmacokinetic model was established. This developed method could be useful to predict pharmacokinetics parameters and valuable for further pharmacokinetics/pharmacodynamics studies.

Development and validation of a rapid LC-MS/MS method to quantify letrozole in human plasma and its application to therapeutic drug monitoring.

A selective, rapid, and sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS) method was developed and validated for the determination of letrozole (LTZ) in human plasma, using anastrozole as internal standard (IS). Sample preparation was performed by one-step protein precipitation with methanol. The analyte and IS were chromatographed on a reversed-phase YMC-ODS-C18 column (2.0 × 100 mm i.d., 3 µm) with a flow rate of 0.3 mL/min. The mobile phase consisted of water containing 0.1% formic acid (v/v) and methanol containing 0.1% formic acid (v/v). The mass spectrometer was operated in selected reaction monitoring mode through electrospray ionization ion mode using the transitions of m/z 286.2 → 217.1 for LTZ and m/z 294.1 → 225.1 for IS, respectively. The method was validated for selectivity, linearity, lower limit of quantitation, precision, accuracy, matrix effects and stability in accordance with the US Food and Drug Administration guidelines. Linear calibration curves were 1.0-60.0 ng/mL. Intra- and inter-batch precision (CV) for LTZ were <9.34%, and the accuracy ranged from 97.43 to 105.17%. This method was successfully used for the analysis of samples from patients treated with LTZ in the dose of 2.5 mg/day. It might be suitable for therapeutic drug monitoring of these patients and contribute to predict the risk of adverse reactions.

Pharmacokinetic properties and bioequivalence of orally inhaled salbutamol in healthy Chinese volunteers.

CONTEXT: Salbutamol is a short-acting ß2-adrenergic receptor agonist that has been used for many years for relief of bronchospasm. However, studies on the pharmacokinetic profile of orally inhaled salbutamol doses used in clinical practice have not yet been reported in Chinese subjects. OBJECTIVE: The aim of this study was to compare the pharmacokinetics and evaluate the bioequivalence of two orally inhaled salbutamol formulations. MATERIALS AND METHODS: A single-dose randomized fasting two-period, two-treatment and two-sequence crossover open-label bioequivalence study was conducted in 24 healthy Chinese adult male volunteers, with a 1-week washout period between treatments. Plasma concentrations of salbutamol were determined using liquid chromatography coupled to tandem mass spectrometry. Pharmacokinetic parameters, including AUC0-0.33 h, AUC0-24 h and Cmax were calculated and the 90% confidence intervals of the ratio (test/reference) pharmacokinetic parameters were obtained by analysis of variance on logarithmically transformed data. RESULTS: The mean (SD) pharmacokinetic parameters of the reference drug were AUC0-0.33 h, 227.2 (89.9) pg·h/ml; AUC0-24 h, 2551.9 (1008.0) pg·h/ml; Cmax, 801.3 (307.3) pg/ml and t1/2, 5.14(1.36) h. Those of the test drug were AUC0-0.33 h, 244.0 (104.4) pg·h/ml; AUC0-24 h, 2664.4 (1081.8) pg·h/ml; Cmax, 873.7 (374.4) pg/ml, t1/2, 5.29 (1.23) h. The median value for Tmax was 0.25 h for both formulations. The 90% confidence intervals for the AUC0-0.33 h, AUC0-24 h and Cmax were in the range of 0.892-1.208, 0.876-1.195 and 0.911-1.203, respectively. CONCLUSION: This single-dose study found that the test and reference products met the regulatory criteria for bioequivalence of China in healthy Chinese volunteers.

Simultaneous quantification of olanzapine and its metabolite N-desmethylolanzapine in human plasma by liquid chromatography tandem mass spectrometry for therapeutic drug monitoring.

A simple, sensitive, and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of olanzapine (OLZ) and its metabolite N-desmethylolanzapine (DMO) in human plasma for therapeutic drug monitoring. Sample preparation was performed by one-step protein precipitation with methanol. The analytes were chromatographed on a reversed-phase YMC-ODS-AQ C18 Column (2.0 × 100 mm,3 µm) by a gradient program at a flow rate of 0.30 mL/min. Quantification was performed on a triple quadrupole tandem mass spectrometer via electrospray ionization in positive ion mode. The method was validated for selectivity, linearity, accuracy, precision, matrix effect, recovery and stability. The calibration curve was linear over the concentration range 0.2-120 ng/mL for OLZ and 0.5-50 ng/mL for DMO. Intra- and interday precisions for OLZ and DMO were <11.29%, and the accuracy ranged from 95.23 to 113.16%. The developed method was subsequently applied to therapeutic drug monitoring for psychiatric patients receiving therapy of OLZ tablets. The method seems to be suitable for therapeutic drug monitoring of patients undergoing therapy with OLZ and might contribute to prediction of the risk of adverse reactions.

Pharmacokinetics and bioequivalence study of three oral formulations of ambroxol 30 mg: a randomized, three-period crossover comparison in healthy volunteers.

OBJECTIVE: To compare the pharmacokinetic properties of two newly developed generic ambroxol formulations with a branded innovator product in healthy Chinese male volunteers. METHODS: This was a single-dose, randomized, open-label, three-period crossover study in healthy volunteers aged 18 - 45 years under fasting conditions. Subjects were assigned to receive 1 of 2 test formulations or a reference tablet of ambroxol 30 mg. Each study period was separated by a 1-week washout phase. Blood samples were collected at pre-specified times. A non-compartmental method was employed to determine pharmacokinetic properties (C(max), t(max), AUC(0-tlast), AUC(0-∞)) to test for bioequivalence. The predetermined regulatory range of 90% CI for bioequivalence was 80 - 125%. RESULTS: 24 subjects were enrolled in and completed the study. The geometric mean C(max) values for the test tablet, test capsule, and reference product were 82.73, 85.36, 84.56 ng/mL, and their geometric mean AUC(0-tlast) (AUC(0-∞)) were 660.87 (753.49), 678.98 (756.79), and 639.41 (712.14) ng x h/mL, respectively. For test tablet vs. reference, the 90% CIs of the least squares mean test/reference ratios of C(max), AUC(0-tlast), and AUC(0-∞) were 91.2% to 104.9%, 96.5% to 110.7%, and 98.8% to 113.4%, respectively. For test capsule, the corresponding values were 94.1% to 108.3%, 99.2% to 113.7%, and 99.2% to 113.9%, respectively. No adverse events occurred during the study. CONCLUSIONS: The ambroxol 30 mg tablets and capsules were considered bioequivalent to the reference formulation in accordance with predetermined regulatory criteria.

Population pharmacokinetic analysis of febuxostat with high focus on absorption kinetics and food effect.

Febuxostat is commonly used in clinic for the treatment of hyperuricemia. Multiple-peak phenomenon has been observed in human plasma concentration-time profiles of febuxostat, but has not been paid enough attention in previous research. This study takes a pivotal step forward by conducting a comprehensive population pharmacokinetic (PopPK) analysis of febuxostat in a healthy Chinese cohort, with a central focus on delineating its absorption profile under contrasting fasting and fed conditions, while concurrently assessing the influence of food alongside other potential covariates on febuxostat's PK profile. The plasma concentration data used for modeling was obtained from two bioequivalence (BE) studies. Subjects were administered febuxostat 20 mg or 80 mg under fasting or fed condition. Goodness-of-fit plots, visual predict check (VPC), and normalized prediction distribution error (NPDE) were used for model evaluation. Based on the established model, PK profiles in healthy Caucasian subjects were simulated with parameter adjustment for race difference on clearance and bioavailability. Data from 128 subjects were used in the PopPK analysis. Febuxostat concentration-time curves were described by a two-compartment model with two deposit absorption compartments and lag times (Tlag). Prandial states (Food) showed significant impact on absorption rate ka1 and ka2, as well as Tlag1, and body weight was identified as a significant covariate on the apparent distribution volume. The PopPK analysis of febuxostat in healthy Chinese volunteers, under both fasted and fed conditions, successfully characterized its PK profile and underscored the significant influence of food on absorption. The potential difference of absorption between Chinese population and Caucasian population indicated from the simulations needs further investigation.

Translate Pharmacokinetics of PD-1/PD-L1 Monoclonal Antibodies from Cynomolgus Monkey to Human: Comparison of Different Approaches.

Antibodies blocking programmed death-1 (PD-1) and its natural ligand programmed death-ligand 1 (PD-L1) have been proved to be promising strategies in recent years. Hundreds of PD-1/PD-L1 antibodies are under development worldwide. Prediction of human pharmacokinetics (PK) in the preclinical stage is critical for designing dosing regimens in first-in-human studies. This study aims to predict the PK of PD-1/PD-L1 antibodies in human by scaling of monkey data. A systematic literature search of published articles on the PK of PD-1/PD-L1 antibodies in cynomolgus monkey and in human was conducted. Allometric scaling (AS), the species time-invariant (STIV) method, as well as physiologically based pharmacokinetic (PBPK) modeling were investigated. Six antibodies (avelumab, atezolizumab, nivolumab, pembrolizumab, cemiplimab, and zimberelimab) were included for investigation. The exponents used in this study were 0.85 and 1 for clearance (CL) and distribution volume (V), respectively, both for AS and STIV methods. The generic PBPK model for macromolecules in PK-Sim was used without further modifications. The dissociation constant of the antibody for binding to FcRn (KD) in endosome space for human was assumed to be two-fold of that for monkey. Predicted human CLs for the majority of drugs were within the observed range, while Vs were not well predicted using the AS method. The STIV method and the generic PBPK model can be employed to translate concentration-time curves of PD-1/PD-L1 antibodies from cynomolgus monkey to human with comparable efficacy. The results of this study provide reference for the early development of PD-1/PD-L1 antibodies.

Physiologically based absorption modeling to predict the bioequivalence of two apixaban formulations.

The equivalence of absorption rates and extents between generic drugs and their reference formulations is crucial for ensuring therapeutic comparability. Bioequivalence (BE) studies are widely utilized and play a pivotal role in substantiating the approval and promotional efforts for generic drugs. Virtual BE simulation is a valuable tool for mitigating risks and guiding clinical BE studies, thereby minimizing redundant in vivo BE assessments. Herein, we successfully developed a physiologically based absorption model for virtual BE simulations, which precisely predicts the BE of the apixaban test and reference formulations. The modeling results confirm that the test and reference formulations were bioequivalent under both fasted and fed conditions, consistent with clinical studies. This highlights the efficacy of physiologically based absorption modeling as a powerful tool for formulation screening and can be adopted as a methodological and risk assessment strategy to detect potential clinical BE risks.

Pharmacokinetics, pharmacodynamics, and safety of frunexian in healthy Chinese volunteer adults: A randomized dose-escalation phase I study.

The purpose of this study was to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of frunexian (formerly known as EP-7041 and HSK36273) injection, a small molecule inhibitor of activated coagulation factor XI (FXIa), in healthy Chinese adult volunteers. This study was a randomized, placebo- and positive-controlled, sequential, ascending-dose (0.3/0.6/1.0/1.5/2.25 mg/kg/h) study of 5-day continuous intravenous infusions of frunexian. Frunexian administration exhibited an acceptable safety profile with no bleeding events. Steady state was rapidly reached with a median time ranging from 1.02 to 1.50 h. The mean half-life ranged from 1.15 to 1.43 h. Frunexian plasma concentration at a steady state and area under the concentration-time curve exhibited dose-proportional increases. The dose-escalation study of frunexian demonstrated its progressively enhanced capacities to prolong activated partial thromboplastin time (aPTT) and inhibit FXIa activity. The correlations between PK and PD biomarkers (aPTT/baseline and FXI clotting activity/baseline) were described by the two Emax models, with the EC50 values of 8940 and 1300 ng/mL, respectively. Frunexian exhibits good safety and PK/PD properties, suggesting it is a promising candidate for anticoagulant drug.

Evaluating the bioequivalence of two pitavastatin calcium formulations based on IVIVC modeling and clinical study.

In vitro-in vivo correlation (IVIVC) allows prediction of the in vivo performance of a pharmaceutical product based on its in vitro drug release profiles and can be used to reduce the number of bioequivalence (BE) studies during product development, and facilitate certain regulatory decisions. Here, we developed an IVIVC model for pitavastatin calcium, a basic Biopharmaceutics Classification System (BCS) II lipid-lowering drug, which was then used to predict the BE outcome of formulations manufactured at two manufacturers. In addition, virtual trials using the IVIVC model using pH 4.0 acetate buffer dissolution showed similarity in areas under the curves and maximum plasma concentration (Cmax ) for test and reference tablets under fasting condition. These predicted results were verified in definitive BE study. In conclusion, we demonstrated that for certain BCS II molecules, IVIVC modeling could be used as a priori to predict the BE outcome.

Physiologically based pharmacokinetic modeling to characterize enterohepatic recirculation and predict food effect on the pharmacokinetics of hyzetimibe.

BACKGROUND AND OBJECTIVE: Hyzetimibe is a cholesterol absorption inhibitor indicated for the treatment of hypercholesterolemia. This study aims to describe the multiple-peak pharmacokinetics (PK) of hyzetimibe and its active metabolite M1 through physiologically-based pharmacokinetic (PBPK) modeling, and to compare the model predictions of a virtual food effect study with the results of a clinical food effect study. METHODS: The plasma concentration data used for PBPK modeling were obtained from a single-dose, two-period crossover bioequivalence study in the fasted state. Advanced Compartmental Absorption and Transit model was used for absorption. Enterohepatic recirculation process was modeled by changing the gut physiological state from fasted to fed at meal time. Based on the established PBPK models, a virtual food effect study was simulated. A clinical food effect study was used for model external validation. RESULTS: PK profiles of hyzetimibe and M1 under fasting condition could be well described by the PBPK model, and the errors of Cmax, AUC0-∞, and AUC0-t were within the two-fold range. Simulated geometric mean ratios (GMRs, fed/fasted) showed that a high-fat breakfast slightly affected the PK of hyzetimibe, expressed as increased Cmax of hyzetimibe (130.6%). Simulated GMRs and 90% confidence intervals of AUC were within the preset bioequivalent range. The results of the simulated virtual food effect trial were consistent with those of the clinical food effect trial. CONCLUSIONS: The established PBPK model could describe the concentration-time profiles of hyzetimibe and M1 well with good prediction performance. A fully mechanistic model of enterohepatic recirculation warrants further investigation.

Bioequivalence Study of Epalrestat for Healthy Chinese Subjects.

Epalrestat is a reversible noncompetitive inhibitor of aldose reductase with selective inhibition of aldose reductase. It can inhibit the accumulation of sorbitol in red blood cells in patients with diabetic peripheral neuropathy and can improve patients' conscious symptoms and neurological dysfunction. This study was designed to evaluate the bioequivalence in healthy Chinese subjects of a new test formulation and reference formulation of oral epalrestat (50 mg) in the fasting state. The study was performed with 44 healthy Chinese subjects according to a randomized 2-way crossover design. The main pharmacokinetic parameters of test formulation and reference formulation as follows: 4793 and 4781 ng/mL for maximum plasma concentration, 8556 and 8431 ng h/mL for area under the plasma concentration-time curve extrapolated to infinity. The test formulation of epalrestat was bioequivalent to the reference formulation. The bioequivalence study of epalrestat in healthy Chinese subjects suggests that the test and reference formulations have similar pharmacokinetics and both formulations are well tolerated in the dose range studied in healthy Chinese subjects. All these findings provided valuable pharmacokinetic knowledge for further clinical development.

In silico prediction of bioequivalence of atorvastatin tablets based on GastroPlus™ software.

The prediction of intestinal absorption of various drugs based on computer simulations has been a reality. However, in vivo pharmacokinetic simulations and virtual bioequivalence evaluation based on GastroPlus™ have not been found. This study aimed to simulate plasma concentrations with different dissolution profiles and run population simulations to evaluate the bioequivalence of test and reference products of atorvastation using GastroPlus software. The dissolution profiles of the reference and test products of atorvastatin (20 mg tablets), and clinical plasma concentration-time data of the reference product were used for the simulations. The results showed that the simulated models were successfully established for atorvastatin tablets. Population simulation results indicated that the test formulation was bioequivalent to the reference formulation. The findings suggest that modelling is an essential tool to demonstrating the possibility of pharmacokinetic and bioequivalence for atorvastatin. It will contribute to understanding the potential risks during the development of generic products.