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.

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.

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.

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.

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

In vivo pharmacokinetic simulations and virtual bioequivalence (BE) evaluation of cilostazol have not yet been described for humans. Here, we successfully developed a physiologically based absorption model to simulate plasma concentrations of cilostazol. In addition, virtual population simulations integrating dissolution of 0.3% sodium dodecyl sulfate water media were executed to evaluate the BE of test and reference formulations. Simulation results show that test and reference formulations were bioequivalent among 28 subjects, but not nine subjects, consistent with clinical studies. The model proved to be an important tool to show potential BE for cilostazol. This finding may facilitate understanding of the potential risks during the development of generic products.

Pharmacokinetics, pharmacodynamics and safety of LPM3480392 in two phase I clinical trials in healthy Chinese male subjects.

Drugs for acute postoperative pain and breakthrough cancer pain are still urgent in clinical. LPM3480392 is a G-protein-biased ligand at the µ-opioid receptor and showed potent analgesia in nonclinical studies. Two phase I studies of LPM3480392 were conducted in healthy Chinese male volunteers to explore its tolerability, pharmacokinetics and pharmacodynamics under single ascending doses (Study I 0.1-3.0 mg, 30 min) and different infusion times (Study II, 0.6-1.0 mg, 2-15 min). There was one serious adverse event (AE) observed in Study II, and the rest AEs were mild or moderate in severity and resolved by the end of the study. Plasma LPM3480392 maximum concentration (Cmax ) (under lower infusion rate) and area under the plasma concentration-time curve (AUCs) were generally increased with dose. Moreover, LPM3480392 at a dose of 0.6 mg under a 2 min infusion rate elicited effective analgesia as the peak effect within 10-30 min, which was measured by cold pain test and pupillometry. These findings suggest that LPM3480392 could be a potential treatment for acute pain management.

Drug-drug interaction study of ciprofol and sodium divalproex: Pharmacokinetics, pharmacodynamics, and safety in healthy Chinese subjects.

Ciprofol (also known as HSK3486) is a promising intravenous anesthetic candidate derived from propofol and independently developed by Haisco Pharmaceutical Group Co., Ltd. (Chengdu, China). Compared with propofol, ciprofol has the potential to reduce the dose required and the associated risks. Ciprofol is extensively metabolized in vivo, and its interaction with other concurrently administered drugs during clinical application is worthy of attention. Therefore, an open-label, two-stage sequential study was performed in healthy subjects who received either a single administration of ciprofol injection or ciprofol injection after oral administration of sodium divalproex. The aim of the study was to evaluate the effects of sodium divalproex on ciprofol with respect to pharmacokinetics, pharmacodynamics, and safety, thus providing a basis for the rational clinical use of ciprofol and sodium divalproex.

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.

Effect of Food on the Pharmacokinetics of Limertinib (ASK120067) and its Main Metabolite in Healthy Chinese Volunteers.

Limertinib (ASK120067) is a newly developed third-generation epidermal growth factor receptor tyrosine kinase inhibitor. This phase I, open-label, 2-period crossover study was conducted to evaluate the effect of food on the pharmacokinetics (PK) of limertinib and its active metabolite CCB4580030 in Chinese healthy volunteers (HVs). HVs were randomly assigned (1:1) to receive a single dose of limertinib (160 mg) under the fasted state in period 1 and fed condition in period 2, or vice versa. Twenty-four HVs were enrolled, and 20 HVs completed both study periods. PK were assessed before dosing and ≤72 hours after dosing. PK parameters were analyzed by a noncompartmental method. Limertinib was absorbed faster in the fasted state compared with the fed state. The geometric mean ratios (fed/fast) of maximum concentration, area under the plasma concentration-time curve from time 0 to the last quantifiable concentration, and area under the plasma concentration-time curve from time 0 to infinity for ASK120067 were 145.5%, 145.4%, and 141.9%, respectively. Geometric mean ratios of the PK parameters of CCB4580030 were >125.00% and 90% confidence intervals were outside the preset bioequivalent range. Safety profiles were similar in both prandial states, and limertinib was well tolerated. Food reduced the rate and increased the extent of limertinib absorption following oral administration. Whether limertinib can be administered regardless of prandial state in patients warrants further investigation of efficacy and safety.

Safety, pharmacokinetics and exploratory exposure-response analysis of CX3002, a novel inhibitor of Xa, in Chinese healthy subjects.

BACKGROUND AND OBJECTIVE: CX3002 is a structurally novel inhibitor of factor Xa, with promising prospects. This study aims to report the results of a first-in-human ascending-dose study of CX3002 in Chinese healthy subjects, and to establish an exploratory population pharmacokinetic/pharmacodynamic (PK/PD) model to investigate the exposure-response relationship of CX3002. METHODS: The randomized, double-blind, placebo-controlled study included six single-dose groups and three multiple-dose groups, with a dose range of 1-30 mg. Safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of CX3002 were evaluated. PK of CX3002 was analyzed using both non-compartment method and population modeling. PK/PD model was developed using nonlinear mixed effect modeling approach and was evaluated by prediction-corrected visual predictive check and bootstrap methods. RESULTS: A total of 84 subjects were enrolled and all participants completed the study. CX3002 exhibited satisfactory safety and tolerability in healthy subjects. Cmax and AUC of CX3002 increased with dose from 1 to 30 mg, but less-than-proportional increases were observed. There was no obvious accumulation with multiple doses. Anti-Xa activity showed dose-related increases after administration of CX3002 but not placebo. The PK of CX3002 was well described by a two-compartment model with a modification of bioavailability according to dose, and anti-Xa activity was described by a Hill function. No covariate was identified significant based on the limited data in this study. CONCLUSIONS: CX3002 was well tolerated and resulted in dose-related anti-Xa activity across the dose range. The PK of CX3002 were predictable, and correlated with PD effects. Continued clinical investigation of CX3002 was supported. Chinadrugtrials.org.cn identifier: CTR20190153.

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.

First-in-human study to investigate the safety and pharmacokinetics of salvianolic acid A and pharmacokinetic simulation using a physiologically based pharmacokinetic model.

Salvianolic acid A (SAA) is a water-soluble phenolic acid component from Salvia miltiorrhiza Bunge currently under development for myocardial protection treatment for coronary heart disease (CHD). We investigated the safety, tolerability, and pharmacokinetics of single and multiple ascending doses of SAA. Additionally, a physiologically based pharmacokinetic (PBPK) model was developed to simulate the pharmacokinetics of SAA. This was a first-in-human (FIH), randomized, double-blind, placebo-controlled, single, and multiple-dose study in 116 healthy Chinese subjects with the range of 10-300 mg and 60-200 mg SAA, respectively. SAA was well tolerated at all dose levels, following both single and multiple doses, with a low overall incidence of treatment-emergent adverse events (TEAEs) which appeared to be no dose-related. The main pharmacokinetic parameter of SAA, assessed by the power model, was the lack of proportionality with the dose range after single dosing. The 90% CIs of the slope ß of Cmax (1.214 [1.150-1.278]) and AUC0-t (1.222 [1.156-1.288]) were not within the predefined acceptance range, and the direction of the deviation was higher than expected. PBPK modeling suggested the transfer ability saturation of hepatic organic anion-transporting polypeptide 1B1 (OATP1B1) and P-glycoprotein (P-gp) might result in a relatively low distribution rate at higher doses. Clinical plasma concentrations observed were in good agreement with PBPK prediction. SAA showed well-characterized pharmacokinetics and was generally well tolerated in the dose range investigated. The PBPK model provides valuable pharmacokinetic knowledge for further clinical development.

Development of a particle swarm optimization-backpropagation artificial neural network model and effects of age and gender on pharmacokinetics study of omeprazole enteric-coated tablets in Chinese population.

BACKGROUND: The effects of age and gender were explored on pharmacokinetics study of omeprazole enteric-coated tablets in Chinese population and a plasma concentration prediction model was developed. All the data (demographic characteristics and results of clinical laboratory tests) were collected from healthy Chinese subjects in pharmacokinetics study using 20 mg omeprazole enteric-coated tablets. A noncompartmental method was used to calculate pharmacokinetic parameters, and 47 subjects were divided into two groups based on the calculation of the median age. Pharmacokinetic data from the low-age and high-age groups or male and female groups were compared by Student t-test. After a total of 12 variables were reconstruct and convert into independent or irrelative variables by principal component analysis, particle swarm optimization (PSO) was used to construct a backpropagation artificial neural network (BPANN) model. RESULT: The model was fully validated and used to predict the plasma concentration in Chinese population. It was noticed that the Cmax, AUC0-t, AUC0-∞ and t1/2 values have significant differences when omeprazole was administered by low-age groups or high-age groups while there were slight or no significant differences of pharmacokinetic data were found between male and female subjects. The PSO-BPANN model was fully validated and there was 0.000355 for MSE, 0.000133 for the magnitude of the gradient, 50 for the number of validation checks. The correlation coefficient of training, validation, test groups were 0.949, 0.903 and 0.874. CONCLUSION: It is necessary to pay attention to the age and gender effects on omeprazole and PSO-BPANN model could be used to predict omeprazole concentration in Chinese subjects to minimize the associated morbidity and mortality with peptic ulcer. TRIAL REGISTRATION: The study was registered in China Drug Clinical Trial Registration and Information Publicity Platform ( http://www.chinadrugtrials.org.cn ), the registration number was CTR20170876, and the full date of registration was 04/AUG/2017.

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.

Evaluation of the relationship between polymorphisms in CYP2C19 and the single-dose pharmacokinetics of omeprazole in healthy Chinese volunteers: A multicenter study.

The aim of this study was to evaluate the relationship between polymorphisms in CYP2C19 and the single-dose pharmacokinetics (PKs) of omeprazole in healthy Chinese volunteers. A 20 mg single dose of omeprazole (Losec) enteric-coated capsules or tablets was orally administered to 656 healthy subjects from eight subcenters. The polymorphic alleles of CYP2C19*2, *3, and *17 were determined by Sanger sequencing and Agena mass array. Plasma concentrations of omeprazole were determined by high-performance liquid-chromatography tandem mass spectrometry. PK parameters of area under the concentration versus time curve (AUC)0-t , AUC from zero to infinity (AUC0-∞ ), maximum plasma concentration (Cmax ), and terminal half-life (t1/2 ) were significantly influenced by CYP2C19 phenotype (all p < 0.001) and diplotype (all p < 0.001), and the same results were obtained in the subgroup analysis of the effects of diet and dosage form. The polymorphisms of CYP2C19*2(rs4244285; all PK parameters p < 0.001) and *3(rs4986893; pCmax  = 0.020, and the p values of other PK parameters were less than 0.001) were significantly associated with the PKs of omeprazole. For CYP2C19*17 (rs12248560), only t1/2 showed a significant correlation (p = 0.032), whereas other PK parameters did not. The present study demonstrated that the Pks of omeprazole is greatly influenced by CYP2C19.

Pharmacokinetic and Bioequivalence Evaluation of 2 Tadalafil Tablets in Healthy Male Chinese Subjects Under Fasting and Fed Conditions.

Tadalafil is an effective, reversible, and competitive phosphodiesterase 5 inhibitor mainly used to treat erectile dysfunction. This study investigated the bioequivalence of generic and marketed formulations of 10-mg tadalafil tablets under fasted and fed conditions. This open-label, randomized, single-dose, 2-period crossover study included 53 healthy Chinese men (aged 20-43 years). Plasma samples were collected from 0.5 hours before treatment to 72 hours after each dose and analyzed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. Pharmacokinetic parameters were calculated using noncompartmental analysis. Safety assessments were performed throughout the study. For the fasted state, the 90% confidence intervals of the geometric mean ratios between the generic and marketed formulations were 86.1% to 99.1% for the maximum plasma concentration and 88.4% to 100.3% for the area under the plasma concentration-time curve from time 0 to infinity, and the corresponding values under the fed state were and 99.9% to 108.4% and 95.7% to 104.3%, respectively. All data were within the accepted bioequivalence range of 80% to 125%. After consuming high-fat, high-calorie meals in the fed condition, the time to the maximum plasma concentration was similar between the formulations, and area under the plasma concentration-time curve from time 0 to infinity and maximum plasma concentration were 10.2% and 6.55% higher, respectively, for the marketed formulation. Thus, food had no clinically relevant effect on tadalafil exposure following a single oral dose in healthy Chinese men. No serious adverse reactions were reported. These results indicated that the analyzed generic and marketed tadalafil tablets were bioequivalent with similar safety profiles.

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.

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.

A validated UPLC-MS/MS method for the determination of CX3002 in human plasma and its application to a pharmacokinetic study.

A simple, selective, rapid, and reliable ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to determine CX3002 in human plasma using CX3002-d3 as the internal standard (IS). After a rapid protein precipitation with acetonitrile (3:1, v/v), the chromatographic separation of CX3002 and IS was performed on a Thermo Hypersil GOLD C18 column (2.1 mm × 50 mm, 1.9 µm) with gradient elution at a flow rate of 0.4 ml/min. Gradient elution was achieved with mobile phase A consisting of water containing 0.1% formic acid and 5 mmol/L ammonium formate and mobile phase B consisting of methanol containing 0.1% formic acid. The detection was performed on AB SCIEX QTRAP® 5500 tandem mass spectrometry in the positive ion mode. Multiple reactions monitoring (MRM) was used for quantitative analysis at transition of m/z 460.3 â†’ 199.3 for CX3002 and m/z 463.3 â†’ 202.3 m/z for IS. The method was fully validated and displayed good linearity over a concentration range of 0.2-400 ng/mL with the correlation coefficient above 0.997. The intra-run and inter-run precision (coefficient of variation, CV) ranged from 0.60%-16.46% and the accuracy bias ranged from -7.09%-9.75%. The mean IS-normalized extraction recovery ranged from 98.30% to 104.52%. The CV(%) of IS-normalized matrix factors at the low and high QC concentration were 4.09% and 1.68%, respectively. The storage stability under different conditions was in accordance with the bioanalytical guidelines. The method was successfully applied to the pharmacokinetic study of CX3002 (30 mg) in healthy Chinese subjects.