Jinliang Chen

Pharmacokinetics, pharmacodynamics, safety, and tolerability of hyzetimibe (HS‐25) in healthy Chinese subjects

Hyzetimibe (HS‐25) is a new cholesterol absorption inhibitor. We performed the first‐in‐human study to assess the safety, tolerability, and pharmacokinetics (including the effect of food) and pharmacodynamics (effect on blood lipid level) following single (1, 3, 5, 10, 20, and 30 mg) and multiple (5, 10, and 20 mg) ascending‐dose of hyzetimibe in healthy subjects. An increase of exposure (area under the plasma concentration–time curve and maximum plasma concentration) to hyzetimibe and hyzetimibe‐glucuronide (HS‐25M1) was observed in an approximately dose‐proportional manner. A terminal half‐life of approximately 21 hours was observed with doses ranging between 5 and 30 mg. Steady state was achieved by day 8 of once‐daily dosing with 1.6‐ and 1.2‐fold accumulation for hyzetimibe and hyzetimibe‐glucuronide, respectively. Food did not have any effect on hyzetimibe and hyzetimibe‐glucuronide exposure. Administration of hyzetimibe once daily for 10 days reduced the levels of low‐density lipoprotein cholesterol levels in healthy subjects and these recovered after discontinuation of this drug. All of the adverse events were mild or moderate in severity, and the majority of them were unrelated to hyzetimibe, with no dose‐dependent trends. These findings suggest that hyzetimibe could be a potential treatment for hypercholesterolemia.

Bioequivalence studies of 2 oral cefaclor capsule formulations in chinese healthy subjects.

An open-label, single-dose, randomized, crossover study was carried out in 20 Chinese healthy male subjects to compare the pharmacokinetics of 2 cefaclor (CAS 53994-73-3) formulations after administration of a single 250 mg dose of each drug with a 1-week wash-out period. Blood samples were collected before and with 6 h after drug administration. Plasma concentrations were determined by high-performance liquid chromatography (HPLC) with UV detector. 2 formulations were evaluated using the following pharmacokinetic parameters: AUC0-t, Cmax and tmax was analyzed nonparametrically. The 90% confidence interval (CI) of the ratios (teat/reference) of log-transformed AUC0-t and Cmax fell within the bioequivalence acceptance range of 80-125%. The results showed that the 90% CI of the ratios of AUC0-t and Cmax were 105.1% (101.0-109.4%) and 92.4% (82.5-103.4%), respectively, which therefore could conclude 2 oral cefaclor capsule formulations of cefaclor are bioequivalent. Both treatments showed similar tolerability and safety.

Bioequivalence evaluation of cefdinir in healthy fasting subjects.

A simple and sensitive HPLC method was developed to determine cefdinir (CAS 91832-40-5) in human plasma. The method was validated by investigating the accuracy and precision for intra- and inter-day runs in a linear concentration from 0.05-2.0 µg/ml. The object of this study was to compare the bioavailability of cefdinir capsule (reference) and cefdinir granule (test) containing 100 mg of cefdinir. A randomized, open-label, single-dose, 2-way crossover bioequivalence study in 20 healthy, Chinese, male subjects was conducted. A 1-week wash-out period was applied. Blood samples were collected before and with 10 h after drug administration. The formulations were compared using the following pharmacokinetic parameters: AUC0-t, AUC0-∞ and C max. The 90% confidence interval (CI) of the ratios of log-transformed AUC0-t and AUC0-∞ were used to assess bioequivalence between the 2 formulations using the equivalence interval of 80 and 125%. The results showed that the 90% CI of the ratios of AUC0-t, AUC0-∞ and C max were 102.5% (94.7-111.0%), 103.4% (94.8-112.7%) and 106.4% (97.0-116.7%), respectively, which indicated 2 formulations of cefidinir are bioequivalent. Both treatments showed similar tolerability and safety.

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.

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.

QUANTITATIVE DETERMINATION OF MEMANTINE IN HUMAN PLASMA BY LIQUID CHROMATOGRAPHY–TANDEM MASS SPECTROMETRY: APPLICATION TO A BIOEQUIVALENCE STUDY

A simple, sensitive, and rapid liquid chromatography-tandem mass spectrometry method for determination of memantine in human plasma was established. A one-step protein precipitation with methanol was used to extract the analyte from plasma samples. Memantine and amantadine (internal standard, IS) were separated on a YMC-ODS-C18 column using 0.1% formic acid and methanol as a mobile phase at a flow rate of 0.3 mL/min. Detection was performed on positive ion mode of the transitions at 180.3→107.3 for memantine and 152.2→135.3 for IS by selected reaction monitoring (SRM). The assay was validated over the concentration range of 0.5–50 ng/mL with a lower limit of quantification (LLOQ) of 0.5 ng/mL. The intra- and inter-batch precision (RSD) were no more than 5.96% and 6.37%, respectively. The accuracy was from −3.02% to 7.74%. The validated method was successfully applied to a randomized, 2-period cross-over bioequivalence study in 22 healthy Chinese volunteers following a single oral dose of 10 mg memantine hydrochloride tablet. The simple, inexpensive protein precipitation and high-throughput method makes it a suitable and valuable tool in the investigation of the clinical pharmacokinetics and bioequivalence.

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

Abstract Context: Salbutamol is a short-acting β2-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.

Quantification of azithromycin in human plasma by liquid chromatography tandem mass spectrometry: application to a bioequivalence study.

A specific, sensitive and rapid liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method has been developed and validated for the determination of azithromycin in human plasma. After deproteinizing the plasma sample with methanol, azithromycin and internal standard (IS: roxithromycin) were separated using a mobile phase comprised of acetonitrile : ammonium acetate buffer (50 mM, containing 0.05% acetic acid)=85:15 on a Hypersil GOLD C18 column (50 mm×2.1 mm ID, dp 1.9 μm). Detection was performed with a tandem mass spectrometer by selective reaction monitoring (SRM) through electrospray ionization. Target ions were monitored at [M+H]+ m/z 749.5→591.5 and 837.7→679.5 in positive electrospray ionization (ESI) mode for azithromycin and IS respectively. Linearity was established for the range of concentrations 2-800 ng/mL with a coefficient of correlation (r) of 0.9996. The lower limit of quantification (LLOQ) was identifiable and reproducible at 2.0 ng/mL. Both intra- and inter-batch standard deviations were less than 15%. The validated method was successfully applied to study the comparative bioavailability of azithromycin for suspension in test vs. reference in healthy Chinese volunteers through the statistical comparison of pharmacokinetic parameters obtained with the two formulations.

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.