LC-MS/MS method for quick detection of vonoprazan fumarate in human plasma: Development, validation and its application to a bioequivalence study.

A liquid chromatography-tandem mass spectrometry method with vonoprazan fumarate-d4 as a stable isotope-labeled internal standard was developed and validated aiming at quantification of vonoprazan fumarate in human plasma for a bioequivalence study. Chromatographic separation was achieved by acetonitrile one-step protein precipitation using a gradient elution of 0.1% formic acid aqueous solution and acetonitrile with a run time of 3.65 min. Detection was carried out on a tandem mass spectrometer in multiple reaction monitoring mode via a positive electrospray ionization interface. The multiple reaction monitoring mode of precursor-product ion transitions for vonoprazan fumarate and vonoprazan fumarate-d4 were m/z 346.0 → 315.1 and 350.0 → 316.0, respectively. The linear range was 0.150-60.000 ng/ml. This method was fully validated with acceptable results in terms of selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, dilution effect, matrix effect, stability, recovery and incurred sample reanalysis. A successful application of this method was realized in the bioequivalence study of vonoprazan fumarate tablet (20 mg) among healthy Chinese volunteers.

Age-related pharmacokinetics differences were observed between young and elderly populations of a novel PDE5 inhibitor, youkenafil, and its metabolite M459.

PURPOSE: Youkenafil is a novel oral selective PDE5 inhibitor for treating Erectile Dysfunction. This investigation assessed pharmacokinetics (PK), safety, and tolerability of youkenafil and its main metabolite (M459) after taking 100 mg youkenafil hydrochloride tablets in elderly and young subjects. METHODS: This Phase I, single-center, open-label, parallel-group, single-dose study was conducted on 24 individuals (12 elders and 12 youngsters). Each subject received a single oral 100 mg youkenafil hydrochloride tablets. Blood samples were collected before medication and up to 48 h after medication for PK analysis. Safety and tolerability were also assessed, including treatment-emergent adverse events (TEAEs), laboratory tests, 12-lead ECG, vital sign inspections, color vision examinations, and physical examinations. RESULTS: Plasma concentrations of youkenafil and M459 were quantified. PK parameters were determined by non-compartmental analysis. Median Tmax of elderly and young groups were both 0.733 h. However, Cmax, AUC0-t, and AUC0-∞ of youkenafil were separately 16.8 %, 37.2 %, and 37.5 % higher in elders and t1/2 of youkenafil was 2.1 h longer in elders. More great differences were observed for M459. T1/2 values were 4.05 h longer in elders, with Cmax, AUC0-t and AUC0-∞ 73.7 %, 81.1 %, and 81.4 % higher in elders. Two (8.3 %) elderly subjects reported TEAEs (all grade Ⅰ in severity) and both recovered without any treatment. No serious adverse reactions (SAEs) or serious unexpected suspected adverse reactions (SUSARs) occurred in this study. CONCLUSIONS: This was the first PK research of youkenafil and M459 in elderly men. PK parameters differences between youkenafil and M459 were comparable between elderly and young groups. Moreover, safety and tolerability of youkenafil were favorable in both groups.

CYP3A inhibitor itraconazole affect pharmacokinetic behavior of famitinib and its active metabolite: results of a single-center, single-arm, open-label and fixed sequence study.

BACKGROUND: Famitinib, the novel oral multitargeting tyrosine kinase inhibitor, was developed for treatment of patients with advanced solid cancer. This investigation assessed the pharmacokinetic (PK) effects of itraconazole, an officially recommended CYP3A4 strong inhibitor, on famitinib and its metabolite (SHR116637). METHODS: A single-center, single-arm, open-label, and fixed sequence study was conducted in 22 healthy subjects. Famitinib was administered as a single oral 15 mg on Day1. Itraconazole 200 mg once daily was given from Day12 to Day24, concomitantly with famitinib on Day15 and for follow-up during Day30 to Day32. Blood sampling followed each famitinib dosage for PK analysis of famitinib and SHR116637. Safety and tolerability were also assessed throughout the treatment. RESULTS: Cmax, AUC0-t and AUC0-∞ were raised by 40.6%, 77.7% and 81.6%, respectively, and t1/2 was prolonged from 36.08 hours to 48.24 hours for famitinib. In contrast, Cmax, AUC0-t and AUC0-∞ were reduced by 63.5%, 42.6%, and 39.0%, respectively, for SHR116637. Eight (36.4%) subjects reported seventeen treatments that emerged adverse events (all grade 1-2 in severity) all recovered at follow-up period. CONCLUSIONS: Single oral dose of 15 mg famitinib and co-therapy with 200 mg intraconazole were safe and well tolerated in healthy subjects. Famitinib should be avoided in conjunction with strong CYP3A inhibitors if possible. TRIAL REGISTRATION: This trial was registered at http://www.chinadrugtrials.org.cn/index.html. (Registration number: CTR20201824.).

Pharmacokinetic and Pharmacodynamic Interactions Between Henagliflozin, a Novel Selective SGLT-2 Inhibitor, and Warfarin in Healthy Chinese Subjects.

PURPOSE: While controlling blood glucose, patients with diabetes and abnormal coagulation should be treated with positive anticoagulation because the hypercoagulable state of their blood is the primary cause of macroangiopathy. The goal of this study was to evaluate the pharmacokinetic and pharmacodynamic (PK/PD) interactions between henagliflozin, a novel selective sodium-glucose cotransporter 2 inhibitor, and warfarin in healthy subjects. METHODS: This single-center, open-label, single-arm clinical study was conducted in 16 healthy male Chinese subjects. According to the study protocol, the PK properties of henagliflozin 10 mg/d and warfarin 5 mg/d were collected and tabulated in accordance with sampling time. All study drugs were given with once-daily administration. Subjects were monitored for adverse reactions and their severity, outcomes, and relationship to study drug. This influences of warfarin on the PK properties of henagliflozin (Cmax,ss and AUCτ,ss), the effects of henagliflozin on the PK properties of warfarin (Cmax, AUC0-t, and AUC0-∞), and the influences of henagliflozin on the PD properties of warfarin (PTmax, PTAUC, INRmax, and INRAUC) were evaluated. FINDINGS: The geometric mean ratios (GMRs; 90% CIs) of henagliflozin Cmax,ss and AUCτ,ss were 101.75% (96.11%-107.72%) and 102.21% (100.04%-104.42%), respectively. The GMRs (90% CIs) of S- and R-warfarin Cmax, AUC0-t, and AUC0-∞ were as follows: Cmax, 114.31% (106.30%-122.91%) and 115.09% (109.46%-121.01%), respectively; AUC0-t, 120.15% (116.71%-123.69%) and 119.01% (116.32%-121.76%); and AUC0-∞, 120.81% (117.17%-124.58%) and 121.94% (118.90%-125.05%). The GMRs (90% CIs) of warfarin PTmax and PTAUC were 92.73% (91.25%-94.22%) and 97.42% (96.61%-98.24%). The GMRs (90% CIs) of warfarin INRmax and INRAUC were 92.66% (91.17%-94.17%) and 97.36% (96.52%-98.21%). A total of 32 cases of mild adverse events were reported, and were recovered/resolved. There were no serious adverse events reported. IMPLICATIONS: No significant clinically relevant effects on the PK/PD properties of henagliflozin or warfarin were found with coadministration of the two drugs in these healthy male Chinese subjects. Based on these findings, it is expected that henagliflozin and warfarin can be used in combination without dose adjustment. Chinadrugtrials.org.cn identifier: CTR20190240.

Quantification of cefaclor in human plasma using SIL-IS LC-ESI-MS/MS for pharmacokinetics study in healthy Chinese volunteers.

A steady, high-efficiency, and precise liquid chromatography-electrospray ionization-tandem mass spectrometry method was established and validated using cefaclor-d5 as the stable isotope-labeled internal standard for quantification of cefaclor in human plasma. One-step protein precipitation was applied to extract human plasma samples using methanol as precipitant. An Ultimate XB C18 column (2.1 × 50.0 mm, 5.0 µm) was used to achieve chromatographic separation. Mobile phases of gradient elution were an aqueous solution containing 0.1% formic acid (mobile phase A) and an acetonitrile solution containing 0.1% formic acid (mobile phase B). Electrospray ionization in positive-ion mode was applied to detect under multiple reaction monitoring mode. Target fragment ion pairs of cefaclor and stable isotope-labeled internal standard, respectively, were m/z 368.2 → 191.1 and m/z 373.2 → 196.1. Linear range of this method was between 20.0 and 10,000.0 ng/ml, with coefficient of determination (R2 ) >0.9900. Seven concentrations of quality control samples were used: 20.0 ng/ml (lower limit of quantitation), 60.0 ng/ml (low quality control), 650 ng/ml (middle quality control), 5000 ng/ml (arithmetic average middle quality control [AMQC]), 7500 ng/ml (high quality control), 10,000 ng/ml (upper limit of quantification), and 40,000 ng/ml (dilution quality control [DQC]). The method was validated for selectivity, lower limit of quantitation, linearity, accuracy, precision, recovery, matrix effect, dilution reliability, stability, carryover, and incurred sample reanalysis. This stable isotope-labeled internal standard liquid chromatography-electrospray ionization-tandem mass spectrometry approach has been successfully applied to study the pharmacokinetics of cefaclor dry suspension among healthy Chinese volunteers.

Three-Period Bioequivalence Study of Sodium Levofolinate Injection With Calcium Levofolinate for Injection and Sodium Folinate for Injection in Healthy Chinese Subjects.

The aim of this study was to compare the bioequivalence and safety of test preparation sodium levofolinate injection with reference preparations of calcium levofolinate for injection and sodium folinate for injection in China. A single-center, randomized, open-label, 3-period, crossover test was conducted on 24 healthy subjects. Plasma concentration of levofolinate, dextrofolinate, and their metabolites l-5-methyltetrahydrofolate and d-5-methyltetrahydrofolate were quantified by a validated chiral-liquid chromatography-tandem mass spectrometry method. All adverse events (AEs) were documented to evaluate safety as they occurred and evaluated descriptively. Pharmacokinetic parameters (maximum plasma concentration, time to maximum concentration, area under the plasma concentration-time curve over the dosing interval, area under the plasma concentration-time curve from time 0 to infinity, terminal elimination half-life, and terminal rate constant) of 3 preparations were calculated. A total of 8 subjects (10 cases) of AEs occurred in this trial. No serious AEs or unexpected serious adverse reactions were observed. Sodium levofolinate was bioequivalent to calcium levofolinate and sodium folinate in Chinese subjects, and the 3 preparations were all well tolerated.

Evaluation of Pharmacokinetic Interactions Between the New SGLT2 Inhibitor SHR3824 and Valsartan in Healthy Chinese Volunteers.

PURPOSE: Hypertension is often observed in patients with diabetes, and the progression of diabetic nephropathy is closely related to blood pressure elevation. Thus, the effects of hypoglycemic drugs on kidney function and pharmacokinetic interactions in combination with antihypertensive and hypoglycemic drugs are of great clinical value. The purpose of this study was to evaluate the pharmacokinetic interactions between henagliflozin (SHR3824), a new sodium-dependent glucose transporter 2 (SGLT2) inhibitor class drug, and valsartan, an angiotensin II receptor blocker. METHODS: A single-center, single-arm, open-label, self-controlled study was conducted in healthy Chinese volunteers. The pharmacokinetic parameters were calculated with Phoenix WinNonlin version 7.0, and the statistical analysis was performed with SAS version 9.4. Data on pharmacokinetic parameters (single and/or steady-state) were collected and tabulated for different analytes (valsartan and SHR3824) according to the sampling time specified in the protocol. Continuous attention was paid to the safety of all subjects. The aim of the study was to evaluate the effect of a single dose of valsartan on the pharmacokinetic behavior of SHR3824 after multiple doses of SHR3824 (Cmax,ss and AUCτ,ss) and the effect of multiple doses of SHR3824 on the pharmacokinetic behavior of valsartan (Cmax, AUC0-24h, and AUC0-∞). A mixed effect model was used to estimate the point estimation and 90% CI of the geometric mean ratio of the corresponding pharmacokinetic indices at the combined-medication stage (SHR3824 + valsartan) and the single-medication stage (SHR3824 or valsartan). FINDINGS: Twelve volunteers were screened into this experiment and underwent blood sampling. The pharmacokinetic properties of SHR3824 were evaluated after its administration alone or in combination with valsartan. Point estimates and 90% CIs of the geometric mean ratio of SHR3824 Cmax,ss and AUCτ,ss were within the conventional bioequivalence range of 80% to 125%. The pharmacokinetic properties of valsartan were evaluated after its administration alone or in combination with SHR3824. The geometric mean ratios and 90% CIs of the valsartan Cmax, AUC0-24h, and AUC0-∞ were also within the range of 80% to 125%. Thirty-four mild adverse events were reported, with no serious adverse events or suspected unexpected serious adverse reactions. IMPLICATIONS: This study provides basis for the clinical co-administration of SHR3824 with angiotensin II receptor blockers represented by valsartan. Based on these findings, co-administration of SHR3824 and valsartan seemed to have no effect on the pharmacokinetic properties of either drug. Chinadrugtrials.org.cn Identifier: CTR20180002.

Establishment and validation of an SIL-IS LC-MS/MS method for the determination of ibuprofen in human plasma and its pharmacokinetic study.

In this work, we developed and validated a highly sensitive, rapid and stable LC-MS/MS method for the determination of ibuprofen in human plasma with ibuprofen-d3 as a stable isotopically labeled internal standard (SIL-IS). Human plasma samples were prepared by one-step protein precipitation. The chromatographic separation was achieved on a Poroshell 120 EC-C18 (2.1 × 50 mm, 2.7 µm). Aqueous solution (containing 0.05% acetic acid and 5 mm NH4 Ac) and methanol were selected as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in negative ion mode. Multiple reaction monitoring mode was used for quantification using target fragment ions m/z 205.0 → 161.1 for ibuprofen and m/z 208.0 → 164.0 for SIL-IS, respectively. This method exhibited a linear range of 0.05-36 µg/ml for ibuprofen with correlation coefficient >0.99. Mean recoveries of ibuprofen in human plasma ranged from 78.4 to 80.9%. The RSD of intra- and inter-day precision were both < 5%. The accuracy was between 88.2 and 103.67%. The matrix effect was negligible in human plasma, including lipidemia and hemolytic plasma. A simple, efficient and accurate LC-MS/MS method was successfully established and applied to a pharmacokinetic study in healthy Chinese volunteers after a single oral administration of ibuprofen granules.

Pharmacokinetic Properties of S-oxiracetam After Single and Multiple Intravenous Infusions in Healthy Volunteers.

BACKGROUND AND OBJECTIVES: As a chiral drug, oxiracetam (ORT) can exist in two different isomeric forms: S-oxiracetam (S-ORT) and R-oxiracetam (R-ORT). S-ORT has emerged as a promising nootropic drug with the potential to treat brain injury and the resulting loss of neural function, memory and mental impairment as assessed by studies in various animal models. However, limited data are available on the pharmacokinetics of S-ORT in humans, so the present study was designed to evaluate the safety and pharmacokinetic profile of S-ORT in healthy volunteers. METHODS: In part 1, subjects were intravenously administered single ascending dose (2.0, 4.0 and 8.0 g) S-ORT. In part 2, subjects were treated at a single intravenous infusion dose of 3.0 g S-ORT or 6.0 g racemic ORT using a two-sequence, two-period crossover design. In part 3, subjects were intravenously injected with 4.0 g S-ORT once a day for 7 days. Blood and urine samples were collected to evaluate the pharmacokinetic parameters and urine excretion rate. The safety profile of the drug was also evaluated throughout the study. RESULTS: Fifty-two subjects (30 in part 1, 12 in part 2, 10 in part 3) completed the study; only one subject displayed a mild adverse event, which possibly was treatment related, and no serious adverse event occurred. In part 1 for a single dose of 2.0, 4.0 and 8.0 g, the maximum concentration (Cmax) values were 111.28 ± 18.99, 230.76 ± 29.16 and 352.67 ± 42.94 µg/ml, respectively; the values of area under the plasma concentration-time curve (AUC) from time zero to the time of last quantifiable concentration (AUC0-t) were 267.09 ± 59.66, 524.50  ± 72.87 and 822.68 ± 95.21 µg·h/ml, respectively; the AUC from 0 h to infinity (AUC0-∞) values were 274.72 ± 61.65, 536.06 ± 78.13 and 832.07 ± 96.91 µg·h/ml, respectively. The urine excretion rate of the unchanged drug was approximately 60%. After consecutive administration of S-ORT for 7 days, the accumulation index was 1.05 ± 0.08. The plasma drug concentration-time curves for both S-ORT and R-oxiracetam (R-ORT) were almost identical. CONCLUSIONS: S-ORT was well tolerated, and no serious adverse events occurred in 2.0, 4.0 and 8.0 g in single- and 4.0 g in multiple-dose studies. S-ORT showed dose linearity with increasing doses and no drug accumulation after 7 days of continuous administration was observed.

Using a stable isotope-labeled internal standard for liquid chromatography-tandem mass spectrometry quantitation of meloxicam in human plasma.

A sensitive and highly efficient LC-ESI-MS/MS method using a stable isotope-labeled internal standard (SIL IS) to detect meloxicam in human plasma was developed and validated. Sample preparation used only 50 µL human plasma with one-step methanol protein precipitation. A gradient mobile phase system was adopted for chromatographic separation on a Poroshell 120 SB-C18 column (2.1 × 50 mm, 2.7 µm). Positive ion pattern was chosen for quantification under multiple reaction monitoring. Ion pairs were [M + H]+ m/z 352.1 → 115.1 for meloxicam and [M + H]+ m/z 355.1 → 187.1 for meloxicam-d3 (SIL IS). Total run time was 4.0 min. Standard curve was linear over a concentration range from 8.00 to 1600 ng mL-1 . This method was fully validated to evaluate its performance, including specificity, carryover, sensitivity, linearity, accuracy, precision, recovery, matrix effects, stability, dilution reliability and incurred sample reanalysis, which provided a reliable basis for pharmacokinetic studies of meloxicam in 28 healthy Chinese volunteers. After a single-dose oral administration of 7.5 mg meloxicam, the main pharmacokinetic parameters were as follows: Cmax , 814.79 ± 201.37 ng mL-1 ; Tmax , 4.54 ± 1.42 h; AUC0-t , 24,572.04 ± 5766.93 ng·h mL-1 ; AUC0-∞ , 25,810.89 ± 6796.60 ng·h mL-1 and t1/2 , 21.11 ± 5.35 h.

[Effect of acupuncture plus medication on expression of Bcl-2 and Bax in hippocampus in rats with Alzheimer's disease].

OBJECTIVE: To explore the mechanism of acupuncture plus medication on treatment of Alzheimer's disease (AD). METHODS: Sixty adult SD rats were randomly divided into a normal group, a sham operation group, a model group, an electroacupuncture (EA) group, a gastrodin group and an EA+gastrodin group, 10 rats in each one. The rat model of AD was established by intraperitoneal injection of D-galactose and bilateral hippocampal injection of Aß1-40. Two weeks after modeling, the rats in the EA group and EA+gastrodin group were treated with EA at "Baihui" (GV 20) "Dazhui" (GV 14) and bilateral "Zusanli" (ST 36), 30 min per treatment, once a day for consecutive 4 weeks. The rats in the gastrodin group and EA+gastrodin group were treated with intraperitoneal injection of gastrodin, once a day for consecutive 4 weeks. The rats in the normal group, model group and sham operation group were not treated. The morphology of hippocampal neurons was observed by using HE staining. The expression of Bcl-2 and Bax in the hippocampal CA1 area was detected by using immunohistochemical method. The expression of Bcl-2 and Bax protein in hippocampus was detected by using Western blot. RESULTS: The HE staining results showed the arrangement of neurons in the hippocampal CA1 area was regular in the normal group and the sham operation group, and the cytoplasm and nucleus were clearly visible. The neurons in the model group were severely damaged; the cell arrangement was not close, and the cell morphology was incomplete. Compared with the model group, the cell morphology of each intervention group was significantly improved. The immunohistochemistry results showed that, compared with the normal group and the sham operation group, the expression of Bcl-2 in the hippocampal CA1 region in the model group was decreased (P<0.05), but the expression of Bax was enhanced (P<0.05); compared with the model group, the expression of Bcl-2 was increased (all P<0.05) and the expression of Bax was decreased (all P<0.05) in all intervention group; compared with the EA group or the gastrodin group, the expression of Bcl-2 was enhanced (P<0.05) and the expression of Bax was decreased (P<0.05) in the EA+gastrodin group. The result of Western blot method was consistent with that of immunohistochemistry method. CONCLUSION: EA and gastrodin could significantly inhibit the expression of Bax and up-regulate the expression of Bcl-2, and the combination of EA and gastrodin has the most significant effect. This indicates that EA combined with gastrodin has synergistic effect on inhibiting the apoptosis of neurons in hippocampus in AD rats, which may be one of the mechanisms of EA plus medication on AD lesions.

Antidepressant effect of helicid in chronic unpredictable mild stress model in rats.

Helicid (4-formylphenyl-ß-D-allopyranoside) is a bioactive constituent of Helicid nilgirica Bedd that has been used in Chinese traditional herbal medicine to treat headache, insomnia, and depression. However, the underlying mechanisms of these effects are unclear. We have now investigated the effect of helicid on depression-related behaviors in rats exposed to chronic unpredictable mild stress (CUMS) and have also explored possible underlying mechanisms that involve neurotrophin expression. After 6 weeks isolation, body weight and sucrose preference were significantly reduced in rats with CUMS-induced depression compared with controls. The CUMS rats also showed significant inhibition of locomotory parameters in open field tests (involving behavioral assays). Helicid significantly regulated levels of corticosterone (CORT), inflammatory cytokines and 5-hydroxytryptamine (5-HT). Helicid also reversed CUMS-induced decreases of 5-HT1A receptor expression and promoted brain derived neurotrophic factor (BDNF) expression in the hippocampus The significant reversal of depressive-like behaviors by helicid is similar to that achieved by fluoxetine. The antidepressive effects are likely attributable to the promotion of hippocampal neurotrophin expression through activation of the serotonergic system. Helicid thus has potential for treating depressive disorders.

Nrf2 is a key factor in the reversal effect of curcumin on multidrug resistance in the HCT­8/5­Fu human colorectal cancer cell line.

Multidrug resistance (MDR) is a major concern when using chemotherapy for the treatment of patients with colorectal cancer. MDR modulators are agents that can reverse MDR and, thus, enhance the chemosensitivity of tumor cells. The development of MDR modulators can improve the therapeutic efficacies of MDR in cancer. However, few effective MDR modulators have been identified so far. Curcumin has been reported to be an effective compound in the reversal of MDR in colorectal cancer cells. However, the mechanisms associated with the reversal effect of curcumin on MDR and its regulation of target factors in MDR cells remain to be fully elucidated. 3­(4,5­dimethyl­2­thiazol)­2,5­diphenyltetrazolium bromide assays, flow cytometer apoptosis assays as well as mRNA and protein expression assays were performed in the present study, and the results confirmed the reversal effect of curcumin on HCT­8/5­Fu cells and provided evidence that activated nuclear factor erythroid 2­related factor (Nrf2) deficiency induced by the curcumin altered the B­cell lymphoma 2 (Bcl­2) associated X protein/Bcl­2 expression ratio, which led to the induction of apoptosis in HCT­8/5­Fu cells. These results indicated that Nrf2 may have a functional in the reversal effect of curcumin and contribute, at least in part, to the outcomes of chemotherapy in patients with MDR.

Simultaneous determination of parecoxib and its main metabolites valdecoxib and hydroxylated valdecoxib in mouse plasma with a sensitive LC-MS/MS method to elucidate the decreased drug metabolism of tumor bearing mice.

Parecoxib (PX), a prodrug of valdecoxib (VX), is an injectable selective COX-2 inhibitor, and is recommended for the treatment of cancer pain. PX can be rapidly hydrolyzed into its active metabolite VX, and VX is further metabolized into hydroxylated valdecoxib (OH-VX) by cytochrome P450 enzymes. However, cancer patients have been reported to possess reduced drug metabolism ability, which might cause excessive drug accumulation. Such overdose of PX significantly increased the risk of renal safety and cardiovascular events. Therefore, it is necessary to elucidate the concentration profiles of PX and its metabolites in cancer status. In this study, a sensitive, rapid and specific LC-MS/MS method for quantification of PX, VX and OH-VX in the plasma of tumor bearing mouse was developed and validated. After protein precipitation, all the analytes were separated on an Agilent ZORBAX Extend-C18 HPLC column (2.1 × 100 mm, 3.5 µm) with gradient elution. The analytes were detected by an electrospray negative ionization mass spectrometry in the multiple reaction monitoring mode. The transition m/z 369.0 → 119.0, m/z 312.9 → 117.9, m/z 329.0 → 196.0, and m/z 307.1 → 161.3 were used for monitoring PX, VX, OH-VX and IS respectively. The calibration curves of the analytes showed good linearity over the concentration range of 3-3000 ng/mL for PX and VX, and 3-1000 ng/mL for OH-VX. Intra- and inter-batch accuracies (in terms of relative error, RE < 9.9%) and precisions (in terms of relative standard deviation, RSD < 8.8%) satisfied the standard of validation. The matrix effect, recovery and stability were also within acceptable criteria. The method was successfully applied to the pharmacokinetics study of PX in tumor bearing mice, and PX and VX levels were found elevated with the growth of tumor volume, which might increase the risk of drug overdose.

Reverse effect of curcumin on CDDP-induced drug-resistance via Keap1/p62-Nrf2 signaling in A549/CDDP cell.

OBJECTIVE: To assess the effect of curcumin on CDDP-induced drug resistance and explore the underlying molecular mechanism through Nrf2 system and autophagy pathway. METHODS: A drug-resistant cell model was established by exposing A549/CDDP cell to 2 µg/mL CDDP. A549/CDDP cell was treated with 20 µg/mL CDDP and 10 µM curcumin. The cell viability and apoptosis level, the signals of Keap1/P62-Nrf2 and autophagy pathway were analyzed. RESULTS: CDDP induction promoted drug-resistant phenotype in A549/CDDP cell and activated autophagy as well as Nrf2 signals in A549/CDDP cell. Meanwhile, curcumin combination attenuated autophagy and Nrf2 activation induced by CDDP, and reversed the drug-resistant phenotype. Notably, curcumin combination augmented Keap1 transcription. Furthermore, Keap1 ablation with short hairpin RNAs hampered the efficacy of curcumin, suggesting Keap1 played a crucial role on reversal effect of curcumin. CONCLUSIONS: The present findings demonstrate that CDDP promotes abnormal activation of Nrf2 pathway and autophagy, leading to drug resistance of A549/CDDP cell. Curcumin attenuates this process and combat drug-resistance through its potent activation on Keap1 transcription, which is essential for interplay between oxidative stress induced Nrf2 activation and autophagy/apoptosis switch.

Effect of OATP1B1 genetic polymorphism on the uptake of tamoxifen and its metabolite, endoxifen.

Overexpression lentivirus platform was established of OATP1B1 (organic anion transporting polypeptides 1B1) wild­type and mutant type genetic polymorphism in vitro, and using this platform we investigated and compared the uptake of tamoxifen and its metabolites by mutating the 388 and the 521 bases. The overexpression lentivirus cell platforms were successfully constructed, including OATP1B1*1a-HEK293T and OATP1B1*1b-HEK293T and OATP1B1*5-HEK293T cell model, the infection efficiency is not less than 80%. It shows a high level of gene expression at the mRNA and protein level. The tamoxifen and endoxifen can be taken up into the cells through organic anion transporter polypeptide 1B1, and OATP1B1521T>C inhibits the function of the transport protein, resulting in the content of drug in cell lysis liquid in OATP1B1*5-HEK293T group is lower than in OATP1B1*1a-HEK293T group (tamoxifen or endoxifen), with statistical significance. The content of the drug in cell lysis liquid in OATP1B1*1b-HEK293T group and the OATP1B1*1a-HEK293T group, similar with no statistical significance. These results suggest that tamoxifen and endoxifen can be transported by OATP1B1. However, OATP1B1 521T>C can inhibit the effects of OATP1B1 on tamoxifen and endoxifen in the cells.

Pharmacokinetic comparisons of S-oxiracetam and R-oxiracetam in beagle dogs.

A pharmacokinetic comparison and conformational stability study of S-oxiracetam (S-ORT) and R-oxiracetam (R-ORT) in beagle dogs was used to investigate the possible mechanism of different effects of two oxiracetam enantiomers through a random crossover design. After drug administration to beagle dogs, blood samples were collected at different time points for pharmacokinetic analysis using the UPLC-ESI-MS/MS method. Parts of plasma samples were used for conformation transformation studies using a normal phase high performance liquid chromatographic (NP HPLC) method. The study showed that oxiracetam enantiomers maintained their original conformation when administered orally to beagle dogs. Concentrations of S-ORT were significantly higher than R-ORT 1.5 and 2 h after administration; the AUC0-∞ of S-ORT after oral administration tended to be higher than that of R-ORT, which showed that the different effects between S-ORT and R-ORT may be partly associated with their distinctive absorption at least.

Bioavailability and pharmacokinetics profile of helicid in beagle dogs using gradient elution high performance liquid chromatography electrospray ionization mass spectrometry.

A simple, sensitive and reliable gradient elution high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) method was developed for quantifying helicid in dog plasma. The limit of detection (LOD) and the lower limit of quantitation (LLOQ) were 0.3 and 1 ng/mL, respectively. This method was validated for selectivity, linearity, accuracy and precision, extraction recoveries, matrix effects, carry-over, cross-talk, dilution integrity, stability and incurred sample reanalysis (ISR). Bioavailability and pharmacokinetic parameters of helicid in beagle dogs were researched from a two period crossover design study. After intravenous administration (i.v.), helicid had a mean (± SD) AUC0-∞ of 12062.06 ± 2482.69 ng/mL h and terminal half-life (t1/2 z) of 2.91 ± 1.37 h, while Cmax was 35613.23 ± 8157.18 ng/mL. Following intragastric gavage administration (i.g.), AUC0-∞ was 7589.16 ± 1797.20 ng/mL h along with a longer t1/2 z of 4.10 ± 4.35 h. Cmax was researched at 0.58 ± 0.20 h. The absolute bioavailability (F) of helicid was 15.74 ± 1.87%.

H nuclear magnetic resonance-based metabolomics reveals sex-specific metabolic changes of gastrodin intervention in rats.

OBJECTIVES: To explore (1)H nuclear magnetic resonance-based metabolomics on sex-specific metabolic changes of gastrodin intervention in rats. METHODS: In this research, (1)H NMR-based metabolomics was used for the first time to investigate metabolic changes following chronic intervention with gastrodin in rats. RESULTS: 24 endogenous metabolites were identified. Body weight, daily diet and the total volume of urine in in each day of each rat were measured synchronously. Modifications in 12 metabolites were observed following gastrodin intervention, indicating gastrodin-induced alterations in carbohydrate and energy metabolism. Interestingly, these metabolic changes were not totally identical in female and male rats. Some metabolic changes arising from gastrodin intervention showed sexual dimorphism including LDL/VLDL and lactate which were on the decrease in the female but on the increase in the male, together with arginine/ornithine, creatine, and glycerol which were on the increase in the female but on the decrease in the male. While the decrease in pyruvate, succinate and glutamate was only shown in the male and the increase in valine, α-ketoglutarate, glycine and glucose was only in the female. CONCLUSIONS: This research shows the sex-specific metabolic response to GAS intervention, weather GAS is a healthy dietary supplement for the male merits further investigation.

Analysis and pharmacokinetics studies of gastrodin and p-hydroxybenzyl alcohol in dogs using ultra fast liquid chromatography-tandem mass spectrometry method.

A simple, sensitive and reliable ultra fast liquid chromatography-electrospray ionization-tandem mass spectrometry (UFLC-ESI-MS/MS) method was developed for simultaneously quantifying gastrodin (p-hydroxy-methyl-phenol-ß-d-glucoside) and its metabolite p-hydroxybenzyl alcohol (HBA) in dog plasma. Separation was performed on an ultra fast liquid chromatography (UFLC) system. Detection was carried out on a tandem mass spectrometry (MS/MS) in multiple reaction monitoring (MRM) mode via an electrospray ionization (ESI) interface. MRM mode of precursor-product ion transitions was used for gastrodin, HBA and the internal standard (IS, bergeninum) at m/z 285.0→123.0, 123.0→105.0 and 326.9→192.2, respectively. The lower limits of quantification (LLOQ) of this method for both gastrodin and HBA were 1ng/mL, with their linear concentration ranging from 0.001 to 10µg/mL. The methods were validated for selectivity, calibration curves, accuracy and precision, extraction recoveries, matrix effects, carry-over, cross talk, dilution integrity, stability and incurred sample reanalysis (ISR). Using this validated method, pharmacokinetic behaviors of gastrodin and HBA after intragastric administration (ig) of gastrodin to dogs were studied for the first time.