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.

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.

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.

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.

CYP2C9*3(1075A > C), ABCB1 and SLCO1B1 genetic polymorphisms and gender are determinants of inter-subject variability in pitavastatin pharmacokinetics.

A pharmacokinetics study was conducted in 12 Chinese volunteers following a single dose of 1 mg, 2 mg and 4 mg of pitavastatin calcium in an open-label, randomized, three-period crossover design. Plasma concentrations of pitavastatin acid and pitavastatin lactone were determined by a HPLC method. Single-nucleotide polymorphisms (SNPs) in ABCB1, ABCG2, SLCO1B1, CYP2C9 and CYP3A5 were determined by TaqMan (MGB) genotyping assay. An analysis was performed on the relationship between the aforementioned SNPs and dose-normalized (based on 1 mg) area under the plasma concentration-time curve extrapolated to infinity [AUC(0-infinity)] and peak plasma concentration (Cmax) values of the acid and lactone forms of pitavastatin. Pitavastatin exhibited linear pharmacokinetics and great inter-subject variability. Compared to CYP2C9*1/*1 carriers, CYP2C9*1/*3 carriers had higher AUC(0-infinity) and Cmax of pitavastatin acid and AUC(0-infinity) of pitavastatin lactone (P<0.05). With respect to ABCB1 G2677T/A, non-G carriers had higher Cmax and AUC(0-infinity) of pitavastatin acid, and Cmax of pitavastatin lactone compared to GT, GA or GG genotype carriers (P<0.05). Gene-dose effects of SLCO1B1 c.521T> C and g.11187G > A on pharmacokinetics of the acid and lactone forms were observed. Compared to non-SLCO1B1*17 carriers, SLCO1B1*17 carriers had higher Cmax and AUC(0-infinity) of the acid and lactone forms (P<0.05). Significant sex difference was observed for pharmacokinetics of the lactone. Female SLCO1B1 521TT subjects had higher Cmax and AUC(0-infinity) of pitavastatin lactone compared to male 521TT subjects, however, such gender difference disappeared in 521 TC and 521CC subjects. Pitavastatin pharmacokinetics was not significantly affected by ABCB1 C1236T, ABCB1C3435T, CYP3A5*3, ABCG2 c.34G > A, c.421C > A, SLCO1B1 c.388A>G, c.571T>C and c.597C>T. We conclude that CYP2C9*3, ABCB1 G2677T/A, SLCO1B1 c.521T>C, SLCO1B1 g.11187G > A, SLCO1B1*17 and gender contribute to inter-subject variability in pitavastatin pharmacokinetics. Personalized medicine should be necessary for hypercholesterolaemic patients receiving pitavastatin.

Simvastatin pharmacokinetics in healthy Chinese subjects and its relations with CYP2C9, CYP3A5, ABCB1, ABCG2 and SLCO1B1 polymorphisms.

A pharmacokinetic study of simvastatin (single oral dose, 40 mg) was conducted in 17 healthy Chinese volunteers. Plasma concentrations of simvastatin were determined by an LC-ESI-MS-MS method. The pharmacokinetic parameters of simvastatin were derived with a non-compartmental method. The polymorphisms of CYP2C9, CYP3A5, ABCB1 (encoding P-gp), ABCG2 (encoding BCRP) and SLCO1B1 (encoding OATP1B1) were determined by TaqMan genotyping assay and the impacts of these SNPs on the pharmacokinetics of simvastatin were analyzed. Major pharmacokinetic parameters were as follows: Tmax 1.44 +/- 0.39 h, Cmax 9.83 +/- 2.41 microg x L(-1), t1/2 4.85 +/- 1.23 h and AUC(0-infinity) 40.32 +/- 6.82 microg x h x L(-1). Effect of ABCB1 G2677T/A SNP on dispostion of simvastatin was observed. Significant differences in t1/2, but not Cmax and AUC(0-infinity), were observed between G/A, G/T or G/G carriers and non-G carriers (5.65 +/- 0.50 h vs 4.41 +/- 1.31 h, P < 0.05). There were no significant effects on simvastatin pharmacokinetics by SNPs such as CYP2C9*3 (1075A > C), CYP3A5*3 g.6986A > G, ABCB1 C3435T, ABCG2 c.34G > A, ABCG2 c.421C>A, SLCO1B1 c.388 A > G, SLCO1B1 c.521 T > C, SLCO1B1 g.11187 G > A, SLCO1B1 c.571 T > C and SLCO1B1 c.597 C > T. We conclude here that there is a small inter-subject variation in simvastatin pharmacokinetics in healthy Chinese volunteers. P-gp, OATP1 B1 and BCRP seem unlikely to play an important role in the pharmacokinetics of simvastatin. The gene-dose effects of ABCG2 c.421 C > A and CYP3A5*3 g.6986A > G on simvastatin pharmacokinetics are not strong enough in Chinese subjects.

ABCB1 gene polymorphisms, ABCB1 haplotypes and ABCG2 c.421c > A are determinants of inter-subject variability in rosuvastatin pharmacokinetics.

A randomized cross-over pharmacokinetic study of rosuvastatin calcium (single dose: 5 mg, 10 mg and 20 mg; multiple doses: 10mg once daily for 7 days) was conducted in 12 healthy Chinese volunteers. Plasma concentrations of rosuvastatin were determined by an LC-ESI-MS-MS method. Single-nucleotide polymorphisms (SNPs) in ABCB1, ABCG2, SLCOB1, CYP2C9 and CYP3A5 were determined by TaqMan (MGB) genotyping assay. An impact of the aforementioned SNPs on steady state pharmacokinetic parameters [average steady state concentration (Cav,ss) and area under the plasma concentration versus time curve during the dosing interval at steady state (AUCss)], dose-normalized (based on 5 mg) pharmacokinetic parameters of single-dose rosuvastatin were further analyzed. Rosuvastatin exhibited linear pharmacokinetics and great inter-subject variability. Cav,ss, AUCss and dose-normalized peak plasma concentration (Cmax) and AUC(0-infinity) of single-dose rosuvastatin were significantly related with ABCB1 C1236T, G2677T/A and C3435T polymorphisms and ABCB1 haplotypes. Compared to homozygous wild type and heterozygous mutation gene carriers, subjects carrying the variant ABCB1 1236TT, 2677 non-G or 3435TT genotype had higher Cav,ss, AUCss, Cmax and AUC(0-infinity) (p < 0.05). ABCB1 haplotype (1236TT-2677TT-3435TT) had significant influence on dose-normalized pharmacokinetics of single-dose rosuvastatin. ABCB1 haplotype (1236TT-2677TT-3435TT) carriers (n = 12) had obvious higher Cmax (11.16 +/- 3.10 microg x L(-1) vs 8.35 +/- 3.31 microg x L(-1), p < 0.05) and AUC(0-infinity) (86.61 +/- 24.32 microg x h x L(-1) vs 62.60 +/- 26.19 microg x h x L(-1), p < 0.05) compared to non-1236TT-2677TT-3435TT carriers (n = 24). ABCG2 c.421C > A had a significant impact on rosuvastatin pharmacokinetics. Homozygotes (AA) carriers had obvious higher Cmax (12.20 +/- 4.09 microg x L(-1) vs 8.70 +/- 3.09 microg x L(-1), p < 0.05) and AUC(0-infinity) (98.74 +/- 25.36 microg x h x L(-1) vs 64.97 +/- 24.90 microg x h x L(-1), p < 0.05) values compared to heterozygotes (CA) and homozygotes (CC) carriers. There were no significant effects on single-dose and steady-state pharmacokinetics of rosuvastatin by CYP2C9*3 (1075A > C), CYP3A5*3 g.6986A > G, ABCG2 c.34G > A, SLCO1B1 c.521 T > C, c.388 A > G, g.11187 G > A, c.571 T > C and c.597 C > T. In addition, no difference in rosuvastatin pharmacokinetics was observed among subjects of different genders. We conclude that ABCB1 C1236T, G2677T/A and C3435T polymorphism, ABCB1 haplotypes and ABCG2 c.421C > A are determinants of inter-subject variability in rosuvastatin pharmacokinetics in healthy Chinese volunteers, and potentially affect the efficacy and toxicity of statin therapy.

Simultaneous determination of paracetamol, pseudoephedrine, dextrophan and chlorpheniramine in human plasma by liquid chromatography-tandem mass spectrometry.

For the first time, a highly sensitive and simple LC-MS/MS method after one-step precipitation was developed and validated for the simultaneous determination of paracetamol (PA), pseudoephedrine (PE), dextrophan (DT) and chlorpheniramine (CP) in human plasma using diphenhydramine as internal standard (IS). The analytes and IS were separated on a YMC-ODS-AQ C(18) Column (100 mm x 2.0 mm, 3 microm) by a gradient program with mobile phase consisting of 0.3% (v/v) acetic acid and methanol at a flow rate of 0.30 mL/min. Detection was performed on a triple quadrupole tandem mass spectrometer via electrospray ionization in the positive ion mode. The method was validated and linear over the concentration range of 10-5000 ng/mL for PA, 2-1000 ng/mL for PE, 0.05-25 ng/mL for DT and 0.1-50 ng/mL for CP. The accuracies as determined from quality control samples were in range of -8.37% to 3.13% for all analytes. Intra-day and inter-day precision for all analytes were less than 11.54% and 14.35%, respectively. This validated method was successfully applied to a randomized, two-period cross-over bioequivalence study in 20 healthy Chinese volunteers receiving multicomponent formulations containing 325 mg of paracetamol, 30 mg of pseudoephedrine hydrochloride, 15 mg of dextromethorphan hydrobromide and 2 mg of chlorphenamine maleate.

Intermittent watt-level ultrasonication facilitates vancomycin release from therapeutic acrylic bone cement.

Ultrasound holds promise for enhancing the vancomycin release from cement though the length of time when local drug level exceeded the minimum inhibitory concentration (T(>MIC)) was not prolonged by the previous protocol of milliwatt-level ultrasonication. Here vancomycin-loaded cements were subjected to continuous watt-level ultrasonication (CUG), intermittent watt-level ultrasonication (IUG) or no ultrasonication (NUG) for 14 d during immersion in 40-ml phosphate buffered saline (PBS) for 28 d. The T(>MIC) for IUG was more than three times that for NUG. In contrast, T(>MIC) for CUG was slightly shortened. The subtherapeutic release of vancomycin between 15 d and 28 d for IUG was one-ninth that for NUG. The fitting equations indicated a significant enhancement on the burst release and the slow release for IUG; however, the continuous ultrasonication hampered the slow release. SEM images exhibited denser craters and pores with larger diameters and less residual drug in specimens from IUG relative to those from both CUG and NUG. Intermittent watt-level ultrasonication improved the ultrasound-enhanced vancomycin release from cement in view of the prolonged T(>MIC) and the inhibited subtherapeutic release compared with continuous ultrasonication. The mechanisms may be associated with the distinctive effects of detaching forces and pushing forces by acoustic microstreams.

Quantitative determination of domperidone in human plasma by ultraperformance liquid chromatography with electrospray ionization tandem mass spectrometry.

A simple and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for determining domperidone in human plasma. The analyte and internal standard (IS; mosapride) were isolated from plasma samples by protein precipitation with methanol (containing 0.1% formic acid). The chromatographic separation was performed on an Xterra MS C(18) Column (2.1 x 150 mm, 5.0 microm) with a gradient programme mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0.30 mL/min. The total run time was 4.0 min. The analyses were carried out by multiple reaction monitoring using the parent-to-daughter combinations m/z 426 --> 175 and m/z 422 --> 198 (IS). The areas of peaks from the analyte and IS were used for quantification of domperidone. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicated that the lower limit of quantification was 0.2 ng/mL, and the assay exhibited a linear range of 0.2-60.0 ng/mL and gave a correlation coefficient (r(2)) of 0.999 or better. Quality control samples (0.4, 0.8, 15 and 50 ng/mL) in six replicates from three different analytical runs demonstrated an intra-assay precision (RSD) 4.43-6.26%, an inter-assay precision 5.25-7.45% and an overall accuracy (relative error) of <6.92%. The method can be applied to pharmacokinetic and bioequivalence studies of domperidone.

Quantitative determination of rosuvastatin in human plasma by liquid chromatography with electrospray ionization tandem mass spectrometry.

A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for determining rosuvastatin in human plasma, a new synthetic hydroxymethylglutaryl-coenzyme A reductase inhibitor. The analyte and internal standard (IS; cilostazol) were extracted by simple one-step liquid/liquid extraction with ether. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The chromatographic separation was performed on an Atlantis C18 column (2.1 mm x 150 mm, 5.0 microm) with a mobile phase consisting of 0.2% formic acid/methanol (30:70, v/v) at a flow rate of 0.20 mL/min. The analyses were carried out by multiple reaction monitoring (MRM) using the precursor-to-product combinations of m/z 482 --> 258 and m/z 370 --> 288. The areas of peaks from the analyte and the IS were used for quantification of rosuvastatin. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicated that the lower limit of quantification (LLOQ) was 0.2 ng/mL and the assay exhibited a linear range of 0.2-50.0 ng/mL and gave a correlation coefficient (r) of 0.9991 or better. Quality control samples (0.4, 8, 25 and 40 ng/mL) in six replicates from three different runs of analysis demonstrated an intra-assay precision (RSD) 7.97-15.94%, an inter-assay precision 3.19-15.27%, and an overall accuracy (relative error) of < 3.7%. The method can be applied to pharmacokinetic or bioequivalence studies of rosuvastatin.

Pharmacokinetics and bioequivalence of ranitidine and bismuth derived from two compound preparations.

AIM: To evaluate the bioequivalence of ranitidine and bismuth derived from two compound preparations. METHODS: The bioavailability was measured in 20 healthy male Chinese volunteers following a single oral dose (equivalent to 200 mg of ranitidine and 220 mg of bismuth) of the test or reference products in the fasting state. Then blood samples were collected for 24 h. Plasma concentrations of ranitidine and bismuth were analyzed by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The non-compartmental method was used for pharmacokinetic analysis. Log-transformed C(max), AUC( (0-t) ) and AUC( (0-infinity) ) were tested for bioequivalence using ANOVA and Schuirmann two-one sided t-test. T(max) was analyzed by Wilcoxon's test. RESULTS: Various pharmacokinetic parameters of ranitidine derived from the two compound preparations, including C(max), AUC( (0-t)), AUC( (0-infinity)), T(max) and T((1/2)), were nearly consistent with previous observations. These parameters derived from test and reference drug were as follows: C(max) (0.67 +/- 0.21 vs 0.68 +/-0.22 mg/L), AUC( (0-t) ) (3.1 +/- 0.6 vs 3.0 +/- 0.7 mg/L per hour), AUC( (0-infinity) ) (3.3 +/- 0.6 vs 3.2 +/- 0.8 mg/L per hour), T(max) (2.3 +/- 0.9 vs 2.1 +/- 0.9 h) and T((1/2)) (2.8 +/- 0.3 vs 3.1 +/- 0.4 h). In addition, double-peak absorption profiles of ranitidine were found in some Chinese volunteers. For bismuth, those parameters derived from test and reference drug were as follows: C(max) (11.80 +/- 7.36 vs 11.40 +/- 6.55 microg/L), AUC( (0-t) ) (46.65 +/- 16.97 vs 47.03 +/- 21.49 microg/L per hour), T(max) (0.50 +/- 0.20 vs 0.50 +/- 0.20 h) and T((1/2)) (10.2 +/- 2.3 vs 13.0 +/- 6.9 h). Ninety percent of confidence intervals for the test/reference ratio of C(max), AUC( (0-t) ) and AUC( (0-infinity) ) derived from both ranitidine and bismuth were found within the bioequivalence acceptable range of 80%-125%. No significant difference was found in T(max) derived from both ranitidine and bismuth. CONCLUSION: The two compound preparations are bioequivalent and may be prescribed interchangeably.