Simultaneous Determination of Ripretinib and Its Desmethyl Metabolite in Human Plasma Using LC-MS/MS.

BACKGROUND: Ripretinib, a recently developed tyrosine kinase inhibitor with switch-control abilities, can inhibit both primary and secondary activation of KIT(KIT proto-oncogene receptor tyrosine kinase) and platelet-derived growth factor receptor alpha (PDGFRA) mutants, which contribute to gastrointestinal stromal tumor progression. METHODS: In this study, a high-performance liquid chromatography-tandem mass spectrometry method to measure the concentrations of ripretinib and its active desmethyl metabolite DP-5439 in human plasma was developed and validated. Plasma samples were extracted and recovered by precipitation with acetonitrile containing the internal standard and diluted with acetonitrile before analysis. Ripretinib and DP-5439 were separated using chromatography on a Waters ACQUITY UPLC HSS T3 column (2.1 mm × 50 mm, 1.8 µm) with gradient elution using 0.1% formic acid and 5 mM ammonium formate in water as mobile phase A and acetonitrile as mobile phase B. The mobile phase was set to a flow rate of 0.5 mL/min. RESULTS: The calibration curves were linear across the following concentration range: 7.5 to 3000 ng/mL for ripretinib and 10 to 4000 ng/mL for DP-5439. The intraday and interday precisions were approximately 15% for all analytes in the quality control samples. The relative matrix effects in extracted plasma samples (90.3%-108.8% at different levels) were considered acceptable. CONCLUSIONS: This method will be a useful tool in oncology to facilitate the further clinical development of ripretinib.

Simultaneous Determination of Ibrutinib, Dihydroxydiol Ibrutinib, and Zanubrutinib in Human Plasma by Liquid Chromatography-Mass Spectrometry/Mass Spectrometry.

BACKGROUND: Ibrutinib and zanubrutinib are Bruton tyrosine kinase inhibitors used to treat mantle cell lymphoma, chronic lymphocytic leukemia, and small lymphocytic lymphoma. Dihydroxydiol ibrutinib (DHI) is an active metabolite of the drug. A liquid chromatography-tandem mass spectrometry method was developed to detect ibrutinib, DHI, and zanubrutinib in human plasma. METHODS: The method involved a protein precipitation step, followed by chromatographic separation using a gradient of 10 mM ammonium acetate (containing 0.1% formic acid)-acetonitrile. Ibrutinib-d5 was used as an internal standard. Analytes were separated within 6.5 minutes. The optimized multiple reaction monitoring transitions of m/z 441.1 → 304.2, 475.2 → 304.2, 472.2 → 455.2, and 446.2 → 309.2 were selected to inspect ibrutinib, DHI, zanubrutinib, and the internal standards in positive ion mode. RESULTS: The validated curve ranges included 0.200-800, 0.500-500, and 1.00-1000 ng/mL for ibrutinib, DHI, and zanubrutinib, respectively. The precisions of the lower limit of quantification of samples were below 15.5%, the precisions of the other level samples were below 11.4%, and the accuracies were between -8.6% and 8.4%. The matrix effect and extraction recovery of all compounds ranged between 97.6%-109.0% and 93.9%-105.2%, respectively. The selectivity, accuracy, precision, matrix effect, and extraction recovery results were acceptable according to international method validation guidelines. CONCLUSIONS: A simple and rapid method was developed and validated in this study. This method was used to analyze plasma concentrations of ibrutinib and zanubrutinib in patients with mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, or diffuse large B-cell lymphoma. The selected patients were aged between 44 and 74 years.

Determination of Orelabrutinib in Human Plasma Using LC-MS/MS.

BACKGROUND: Orelabrutinib is a second-generation Bruton tyrosine kinase inhibitor that improves the management of B-cell malignancies. The objective of this study was to develop and validate an LC-MS/MS method for quantifying orelabrutinib in human plasma. METHODS: Plasma samples were processed using acetonitrile to precipitate proteins. Ibrutinib-d5 was used as the internal standard. The mobile phase comprised 10 mM ammonium formate containing 0.1% formic acid and acetonitrile (62:38, vol/vol). The multiple reaction monitoring transitions at m / z = 428.1 → 411.2 and 446.2 → 309.2 were selected for orelabrutinib and ibrutinib-d5, respectively, after ionization in the positive mode. RESULTS: Total runtime was 4.5 minutes. The validated curve ranges were 1.00-500 ng/mL. This method exhibited acceptable selectivity, dilution integrity, matrix effects, and recovery. Interrun and intrarun accuracy ranged from -3.4% to 6.5%, and interrun and intrarun precision was between 2.8% and 12.8%. Stability was studied under different conditions. The incurred sample reanalysis demonstrated good reproducibility. CONCLUSIONS: The LC-MS/MS method provided a simple, specific, and rapid quantification of orelabrutinib in the plasma of patients with mantle cell lymphoma or chronic lymphocytic leukemia/small lymphocytic lymphoma. The results indicated that orelabrutinib exhibits large variability between individuals and should be prudently used in combination with CYP3A4 inhibitors.

LC-MS/MS methods for determination of venetoclax in human plasma and cerebrospinal fluid.

We developed and validated sensitive MS/MS methods for the determination of venetoclax, an oral selective B-cell lymphoma-2 inhibitor, in human plasma and cerebrospinal fluid (CSF). Acetonitrile was used as protein precipitant. The mobile phase was 10 mM ammonium formate consisting of 0.1% formic acid and acetonitrile (40:60, v/v). The analytes were separated on an ACQUITY UPLC HSS T3 column (2.1 × 50 mm, 1.8 µm) in 5 min. An API 4000 mass spectrometer was selected to quantify venetoclax and internal standard using m/z 868.3 → 636.3 and 876.3 → 644.3 under multiple response monitoring mode. In plasma, the calibration curve exhibited good linearity ranging from 20.0 to 5000 ng/mL, whereas in the CSF, the linear range was 0.500-100 ng/mL. The matrix effect of venetoclax and internal standard (venetoclax-d8) was not obvious in both plasma and CSF. The inter- and intra-run accuracy was within ±11.9%, and the inter- and intra-run precision was below 13.6%. Both methods had no carryover, and the recovery was close to 100%. The validated methods were employed to quantify the concentrations of venetoclax in the plasma and CSF of patients diagnosed with chronic lymphocytic leukemia or acute myelogenous leukemia.

Simultaneous Determination of Orelabrutinib, Zanubrutinib, Ibrutinib and Its Active Metabolite in Human Plasma Using LC-MS/MS.

Ibrutinib, orelabrutinib, and zanubrutinib are all Bruton's tyrosine kinase inhibitors, which have greatly improved the treatment of B-cell malignancies. In this study, an LC-MS/MS method was developed and validated for the determination of orelabrutinib, zanubrutinib, ibrutinib, and its active metabolite dihydrodiol ibrutinib in human plasma. The Ibrutinib-d5 was used as the internal standard. Pretreatment was performed using a simple protein precipitation step using acetonitrile. The ACQUITY UPLC HSS T3 column (2.1×50 mm, 1.8 µm) was used to separate the analytes, and the run time was 6.5 min. The mobile phase consisted of acetonitrile and 10 mM of ammonium formate, which contained 0.1% formic acid. The multiple reactions' monitoring transitions were selected at m/z 428.1→411.2, 472.2→455.2, 441.1→304.2, 475.2→304.2 and 446.2→309.2 respectively for orelabrutinib, zanubrutinib, ibrutinib, dihydrodiol ibrutinib and ibrutinib-d5 using positive ion electrospray ionization. The standard curves were linear, from 0.400 to 200 ng/mL for ibrutinib and dihydrodiol ibrutinib, 1.00-500 ng/mL for orelabrutinib, and 2.00-1000 ng/mL for zanubrutinib. Selectivity, the lower limit of quantitation, precision, accuracy, matrix effect, recovery, stability, and dilution integrity all met the acceptance criteria of FDA guidance. This method was used to quantify the plasma levels of orelabrutinib, zanubrutinib, ibrutinib, and dihydrodiol ibrutinib in clinical patients.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the quantification of regadenoson in human plasma and its pharmacokinetic application.

Regadenoson, the first selective adenosine A2A receptor agonist, is used to perform exercise stress test during radionuclide myocardial perfusion imaging. To detect the concentration of regadenoson in human plasma, a simple, fast, and sensitive tandem mass spectrometry method was established herein. Acetonitrile was used as a protein precipitation agent. Chromatographic separation was completed in 6.5 min using a BEH HILIC column (50 × 2.1 mm, 1.7 µm). The mobile phase consisted of 10 mmol/L ammonium acetate/acetonitrile (gradient elution). To quantify regadenoson and regadenoson-d3, an API 4000 mass spectrometry in multiple reaction monitoring mode with transitions of 391.3→259.2 and 394.3→262.2, respectively, was utilized. The calibration curve was linear in the range of 0.100-50.0 µg/L, and the intrabatch and interbatch precisions were <9.7% and <13.0%, respectively, and the accuracy was 2.0-6.9%. There was no apparent matrix effect for regadenoson or regadenoson-d3. The developed method was used to study the pharmacokinetic characteristics of regadenoson in healthy Chinese subjects.

LC-MS/MS methods for determination of unstable pivmecillinam and mecillinam in acidified human plasma: Application to a pharmacokinetic study.

Pivmecillinam, the ester of biologically active antibiotic mecillinam, is an effective oral preparation to treat urinary tract infections. To study pharmacokinetics in humans, LC-MS/MS methods were developed to quantify pivmecillinam and mecillinam in human plasma, respectively. Considering cephalexin as internal standard, analytes were separated on UltimateXB-C18 columns after protein precipitation by acetonitrile. The mobile phase was composed of water containing 0.1% formic acid and methanol. The multiple reactions monitoring transitions of m/z 440.2→167.1, 326.1→167.1, and 348.1→158.1 were selected to inspect pivmecillinam, mecillinam, and the internal standard in positive ion mode. No apparent matrix effect was perceived. Linearities were obtained over calibration ranges of 0.0500-12.0 and 10.0-15,000 ng/mL, respectively. The intraday precisions were below 5.5%, the interday precisions were below 6.1%, and accuracies were within -8.1 to 13.0%. Stability tests were conducted and an acidification step was explored to enhance the stability of pivmecillinam and mecillinam. Further stability was validated under various storage and processing conditions. Both methods were applied to a pharmacokinetic study of pivmecillinam and mecillinam after oral administration of 400 mg pivmecillinam hydrochloride tablets in healthy Chinese subjects.

Imatinib-induced hepatotoxicity via oxidative stress and activation of NLRP3 inflammasome: an in vitro and in vivo study.

Imatinib (IM), a milestone drug used in the field of molecular targeted therapy, has been reported to cause serious adverse liver effects, including liver failure and even death. Immune-mediated injury and mitochondrial dysfunction are involved in drug-induced liver injury. However, the mechanism of IM-induced hepatotoxicity remains unclear and warrants further study. In our study, Sprague Dawley rats were administered IM by gavage with 50 mg/kg body weight (BW) once daily for 10 days. Drug-induced liver injury accompanied by inflammatory infiltration was observed in rats following IM exposure, and the expression of NOD-like receptor protein 3 (NLRP3) inflammasome-related proteins was significantly increased compared with that of the control. HepG2 cells were exposed to 0-100 µM IM for 24 h. The results showed that IM decreased cell viability in a dose-dependent manner. Moreover, IM induced a state of obvious oxidative stress and activation of nuclear factor kappa B (NF-κB) in cells, which resulted in the activation of NLRP3 inflammasomes, including caspase 1 cleavage and IL-1ß release. These results were significantly reduced after the use of the antioxidants N-acetyl-l-cysteine or the NF-κB inhibitor pyrrolidine di-thio-carbamate. Furthermore, NLRP3 knockdown significantly reduced the release of inflammatory cytokines and improved cell viability. In summary, our data demonstrated that oxidative stress and NLRP3 inflammasome activation are involved in the process of IM-induced hepatotoxicity. The results of this study provide a reference for the prevention and treatment of IM-induced hepatotoxicity.

Impact of CYP2C19 genotype on voriconazole exposure and effect of voriconazole on the activity of CYP3A in patients with haematological malignancies.

Voriconazole (VRC) is a first-line drug for the treatment of invasive fungal infections (IFIs) and an inhibitor of CYP3A activity. The aims of this study are to investigate the influence of related factors on the plasma concentration of voriconazole and the effect of voriconazole on the activity of CYP3A in patients with haematological malignancies.A total of 89 patients received an initial dose of 6 mg/kg followed by 4 mg/kg every 12 h were included in the study. Blood samples were collected before and 2 h after administration for subsequent testing and for the extraction of DNA samples. Voriconazole and voriconazole N-oxide in the plasma were detected by LC-MS/MS. The effect of voriconazole on CYP3A activity was evaluated by the ratio of the endogenous biomarkers 6ß-hydroxycortisol and cortisol.During the study period, the overall incidence of adverse reactions was 33.6% (with no deaths). The metabolite type of CYP2C19 and combined use of CYP2C19 enzyme inhibitors both had a significant impact on voriconazole exposure. Voriconazole has a long-lasting and potent inhibitory effect on CYP3A activity. The exposure of CYP3A substrate in combination with metabolic enzyme inhibitors voriconazole could increase. Therefore, the combination uses with voriconazole need to be considered carefully and assessed adequately.

COVID-19 patients' clinical characteristics, discharge rate, and fatality rate of meta-analysis.

The aim of this study was to analyze the clinical data, discharge rate, and fatality rate of COVID-19 patients for clinical help. The clinical data of COVID-19 patients from December 2019 to February 2020 were retrieved from four databases. We statistically analyzed the clinical symptoms and laboratory results of COVID-19 patients and explained the discharge rate and fatality rate with a single-arm meta-analysis. The available data of 1994 patients in 10 literatures were included in our study. The main clinical symptoms of COVID-19 patients were fever (88.5%), cough (68.6%), myalgia or fatigue (35.8%), expectoration (28.2%), and dyspnea (21.9%). Minor symptoms include headache or dizziness (12.1%), diarrhea (4.8%), nausea and vomiting (3.9%). The results of the laboratory showed that the lymphocytopenia (64.5%), increase of C-reactive protein (44.3%), increase of lactic dehydrogenase (28.3%), and leukocytopenia (29.4%) were more common. The results of single-arm meta-analysis showed that the male took a larger percentage in the gender distribution of COVID-19 patients 60% (95% CI [0.54, 0.65]), the discharge rate of COVID-19 patients was 52% (95% CI [0.34,0.70]), and the fatality rate was 5% (95% CI [0.01,0.11]).

Correction to: Intrathecal Epigallocatechin Gallate Treatment Improves Functional Recovery After Spinal Cord Injury by Upregulating the Expression of BDNF and GDNF.

Since the publication of our article [1] it has come to our attention that there was an error in Figure 4 in which the bottom left immunochemistry panel Control/Bax was a duplication of the bottom right immunohistochemistry panel EGCG/GDNF in Figure 3.

Effects of genetic polymorphisms on the pharmacokinetics and pharmacodynamics of proton pump inhibitors.

Proton pump inhibitors (PPIs) are used widely for the treatment of acid-related disorders. Despite their excellent efficacy and tolerance, the pharmacodynamics and pharmacokinetics of PPIs are affected by each patient's CYP2C19 and gastric H+,K+-ATPase genotype. The aim of this review was to analyze the effect of genetic polymorphisms on the pharmacodynamic and pharmacokinetic properties of PPIs. The gastric acid-suppressive effect of PPIs is affected by both gastric H+,K+-ATPase and CYP2C19 polymorphisms, although gastric H+,K+-ATPase polymorphisms may have larger effects. Ilaprazole and rabeprazole show relatively small differences in the pharmacokinetic and pharmacodynamic properties and clinical efficacy among the different CYP2C19 genotypes. Compared with oral administration, the intravenous infusion of PPIs is less affected by CYP2C19 polymorphism. At the same dose, each enantiomer has less variation among different CYP2C19 genotypes than a racemate mixture.

Simultaneous enantioselective determination of omeprazole, rabeprazole, lansoprazole, and pantoprazole enantiomers in human plasma by chiral liquid chromatography-tandem mass spectrometry.

Proton pump inhibitors, including omeprazole, rabeprazole, lansoprazole, and pantoprazole, achieved simultaneous enantioselective determination in the human plasma by chiral liquid chromatography-tandem mass spectrometry. The four corresponding stable isotope-labeled proton pump inhibitors were adopted as the internal standards. Each enantiomer and the internal standards were extracted with acetonitrile containing 0.1% ammonia, then separated with a Chiralpak IC column (5 µm, 4.6 mm × 150 mm) within 10 min. The mobile phase was composed of acetonitrile-ammonium acetate (10 mM) containing 0.2% acetic acid (50:50, v/v). To quantify all enantiomers, an API 4000 tandem mass spectrometer was used, and multiple reaction monitoring transitions were performed on m/z 360.1→242.1, 384.1→200.1, 370.1→252.1, and 346.1→198.1, respectively. No significant matrix effect was observed for all analytes. The calibration curve for all enantiomers were linear from 1.25 to 2500 ng/mL. The precisions for intra- and inter-run were < 14.2%, and the accuracy fell in the interval of -5.3 to 8.1%. Stability of samples was confirmed under the storage and processing conditions. The developed method was also suitable for separation and determination of ilaprazole enantiomers. The validated method combining the equilibrium dialysis method was applied to the protein binding ratio studies of four pairs proton pump inhibitor enantiomers in human plasma.

Impact of 14 types of genetic polymorphisms on antihypertensive efficacy of felodipine in healthy Chinese subjects
.

OBJECTIVE: This study evaluated different influences of 14 single nucleotide polymorphisms (SNPs) and demographic factors leading to individual differences in the antihypertensive efficacy of felodipine in healthy Chinese subjects. MATERIALS AND METHODS: 24 subjects were sequenced for candidate SNPs. Plasma samples were obtained as clinical trial protocol, and were determined by a HPLC-MS/MS method. Pharmacokinetic parameters were calculated by WinNonlin 6.0. Statistical analysis was mainly performed by SPSS 22.0. A multiple linear regression model provided different weight coefficients of different demographic and genetic factors. RESULTS: The trend of Cmax is almost consistent with AUCss increase, but tmax of individuals is different; the antihypertensive effect of felodipine is individually different. A significant association was observed between systolic blood pressure decrease (ΔSBP) and SNPs of CACNA1C, CACNA1D, GNB3 respectively, while CACNA1C and CACNA1 were associated with diastolic blood pressure decrease (ΔDBP). CYP3A5 rs766746 and CYP3A4 rs2242480 were linked with Cmax and AUCss, and ABCB1 rs1045642 was associated with T1/2. Significant relationships were shown between AUCss and ΔSBP (p = 0.022) as well as Cmax and ΔSBP (p = 0.015). CONCLUSION: The efficacy of felodipine is individually different, influenced especially by CACNA1C rs1051375 and ABCB1 rs1045642. ΔDBP is associated with ΔSBP in multiple-dosing of felodipine in healthy Chinese subjects.

Comparison of the gastric acid inhibition function among lansoprazole, pantoprazole, and their respective stereoisomers in healthy Chinese subjects
.

OBJECTIVE: This study was conducted to evaluate the difference in acid inhibition function among lansoprazole (LPZ), pantoprazole (PPZ), and their respective stereoisomers following single and multiple intravenous doses in healthy Chinese subjects. MATERIALS AND METHODS: The dosage groups were set as follows: 30 mg single and multiple intravenous administrations of LPZ or R-LPZ, 40 mg single and multiple intravenous administrations of PPZ or S-PPZ. Subjects received an intravenous infusion of LPZ, R-LPZ, PPZ, or S-PPZ injection in sterile saline solution (100 mL/h, 60 minutes), respectively. The intragastric pH was sampled every second for 24 hours at baseline and for 24 hours after drug administration. The baseline-adjusted pharmacodynamic (PD) parameters include ΔMean (pH), ΔMedian (pH), ΔTpH≥3 (%), ΔTpH≥4 (%), ΔTpH≥6 (%), and ΔAUECph-tτ1-τ2. The PD parameters were evaluated in different time intervals (0 - 24 hours, 0 - 4 hours and 14 - 24 hours). RESULTS: After a single dose, the ΔTpH≥4 (%) of R-LPZ, LPZ, S-PPZ and PPZ was 56.6 ± 19.6, 53.1 ± 23.3, 35.6 ± 24.9 and 26.8 ± 30.2, respectively. The ΔTpH≥6 (%) was 50.7 ± 26.1, 41.4 ± 26.2, 25.4 ± 24.9 and 22.1 ± 27.6, respectively. The ΔAUECph-τ1-τ was 45,564 ± 16,107, 41,798 ± 16,153, 31,914 ± 17,304 and 20,744 ± 21,500, respectively. Statistically significant differences were found with R-LPZ vs. S-PPZ, R-LPZ vs. PPZ, LPZ vs. S-PPZ and LPZ vs. PPZ. The average TpH≥4 of R-LPZ, LPZ, S-PPZ, and PPZ was (47.2 ± 26.1) minutes, (49.6 ± 19.3) minutes, (56.1 ± 23.7) minutes, and (72.1 ± 27.3) minutes, respectively. Statistically significant differences were found with R-LPZ vs. PPZ (p = 0.009) and LPZ vs. PPZ (p = 0.019). After multiple doses, the ΔTpH≥4 (%) of R-LPZ, LPZ, S-PPZ, and PPZ was 71.7 ± 20.2, 63.5 ± 19.4, 59.5 ± 17.8 and 64.0 ± 22.4, respectively. The ΔTpH≥6 (%) was 64.0 ± 22.2, 52.0 ± 19.2, 49.6 ± 20.4 and 50.9 ± 23.8, respectively. The ΔAUECph-τ1-τ was 326,149 ± 94,839, 288,565 ± 93,279, 296,189 ± 83,412 and 300,960 ± 108,057, respectively. No statistically significant differences were found in baseline-adjusted PD parameters during all time periods after multiple doses. CONCLUSION: After a single dose, the mean gastric pH inhibition value of R-LPZ was the highest, followed by LPZ, then S-PPZ and PPZ. R-LPZ and LPZ provided significantly better pH control compared with PPZ and S-PPZ in healthy subjects. The onset time of R-LPZ was the fastest and R-LPZ can provide better acid inhibition during sleeping time. After multiple doses, the mean values in all PD parameters of R-LPZ were the highest, the values of LPZ, S-PPZ, and PPZ were similar. However, no significant difference was found in acid inhibition among these four drugs after multiple doses.

[Screening of long non-coding RNA related to CYP450s involved in biosynthesis of tanshinones].

Tanshinones are abietane-type norditerpenoid quinones that make up the main bioactive ingredients of traditional Chinese medicine Salvia miltiorrhiza. Cytochrome CYP450 plays an important role in the post-structural modification of tanshinone biosynthesis pathway. Long non-coding RNA( lncRNA) have been defined as transcripts longer than 200 nucleotides,which have been functionally characterized in regulating the growth and development,secondary metabolism and stress of medicinal plants. In this study,we perform a comprehensive identification of lncRNAs in response to tanshinone metabolism induced by yeast extract( YE) and Ag~+ S. miltiorrhiza hairy roots. Deep RNA sequencing was used to identify a set of different 8 942 lncRNAs,of which 6 755 were intergenic lncRNAs. We predicted a total of 1 115 814 lncRNA-coding gene pairs,including 122 lncRNA-coding gene as cis pairs. The correlation analysis between lncRNA and CYP450 related to tanshinone biosynthesis was carried out and a total of 16 249 lncRNA-CYP450 target gene pairs were identified. Further analysis with functional known CYP76 AH1,CYP76 AH3 and CYP76 AK1 involved in tanshinone biosynthesis,we also identified a set of 216 target genes. These candidate genes will be the important target in the downstream regulation mechanism analysis of the tanshinone biosynthesis pathway.

Peptide selectivity between the PDZ domains of human pregnancy-related serine proteases (HtrA1, HtrA2, HtrA3, and HtrA4) can be reshaped by different halogen probes.

The human HtrA family of serine proteases (HtrA1, HtrA2, HtrA3, and HtrA4) are the key enzymes associated with pregnancy and closely related to the development and progression of many pathological events. Previously, it was found that halogen substitution at the indole moiety of peptide Trp-1 residue can form a geometrically satisfactory halogen bond with the Drosophila discs large, zona occludens-1 (PDZ) domain of HtrA proteases. Here, we attempt to systematically investigate the effect of substitution with 4 halogen types and 2 indole positions on the binding affinity and specificity of peptide ligands to the 4 HtrA PDZ domains. The complex structures, interaction energies, halogen-bonding strength, and binding affinity of domain-peptide systems were modeled, analyzed, and measured via computational modeling and fluorescence-based assay. It is revealed that there is a compromise between the local rearrangement of halogen bond involving different halogen atoms and the global optimization of domain-peptide interaction; the substitution position is fundamentally important for peptide-binding affinity, while the halogen type can effectively shift peptide selectivity between the 4 domains. The HtrA1-PDZ and HtrA4-PDZ as well as HtrA2-PDZ and HtrA3-PDZ respond similarly to different halogen substitutions of peptide; -Br substitution at R2-position and -I substitution at R4-position are most effective in improving peptide selectivity for HtrA1-PDZ/HtrA4-PDZ and HtrA2-PDZ/HtrA3-PDZ, respectively; -F substitution would not address substantial effect on peptide selectivity for all the 4 domains. Consequently, the binding affinities of a native peptide ligand DSRIWWV-COOH as well as its 4 R2-halogenated counterparts were determined as 1.9, 1.4, 0.5, 0.27, and 0.92 µM, which are basically consistent with computational analysis. This study would help to rationally design selective peptide inhibitors of HtrA family members by using different halogen substitutions.

Safety, pharmacokinetics, and pharmacodynamics of S-(-)-pantoprazole sodium injections after single and multiple intravenous doses in healthy Chinese subjects.

PURPOSE: The objective of this study was to evaluate the safety, pharmacokinetics, and pharmacodynamics of S-(-)-pantoprazole (PPZ) sodium injections following single and multiple intravenous doses in healthy Chinese subjects. METHODS: The dosage groups were set as followed: 20 mg of single and multiple intravenous administration of S-(-)-PPZ, 40 mg of single and multiple intravenous administration of S-(-)-PPZ or pantoprazole, and 80 mg of single dosage group of S-(-)-PPZ. Subjects were sampled for pharmacokinetic analysis and were monitored for 24-h intragastric pH prior to and 48-h intragastric pH after administration for the pharmacodynamic study. The pharmacokinetic and pharmacodynamic parameters were compared between S-(-)-PPZ and PPZ. Safety was evaluated on the basis of adverse events, vital signs, laboratory tests, and physical examination. RESULTS: All adverse events were mild and of limited duration. Maximum plasma concentration and area under the concentration-time curve for S-(-)-PPZ were dose proportional over the range of 20-80 mg following a single intravenous administration. Elimination rate constant and half-life observed statistical difference from a single dose to multiple doses in 40 mg of S-(-)-PPZ groups. After administration of a single dose, the mean 24-h intragastric pH value was observed higher in 80-mg group than in 40- and 20-mg groups. Slightly increase of intragastric pH was found after a single dose of 40 mg S-(-)-PPZ than 40 mg PPZ; however, the differences were not statistically significant. CONCLUSIONS: Twice daily of 40 mg S-(-)-PPZ sodium injections is effective in achieving satisfying acid inhibition. Compared with plasma R-(+)-PPZ levels, most subjects presented more potent and prolonged suppression of gastric acid of S-(-)-PPZ, while a few subjects showed faster metabolic rate of S-(-)-PPZ in vivo.

Stereoselective pharmacokinetics of (R)-(+)- and (S)-(-)-rabeprazole in human using chiral LC-MS/MS after administration of rabeprazole sodium enteric-coated tablet.

Rabeprazole is an effective proton pump inhibitor to treat acid-related diseases. To achieve the simultaneous determination of rabeprazole enantiomers in human plasma, a chiral LC-MS/MS method was developed and validated. Acetonitrile including 0.1% ammonium were used as protein precipitating agent. Analytes were separated within 8 minutes on a Chiralpak IC column (4.6 mm × 150 mm, 5 µm). The mobile phase was 10 mM ammonium acetate including 0.2% acetic acid-acetonitrile (35:65, v/v). An API 4000 mass spectrometer was used as detector for the analysis, and the multiple reactions monitoring transitions of m/z 360.1 â†’ 242.2 and 346.1 â†’ 198.1 were opted for quantifying rabeprazole enantiomers and internal standard. Matrix effects were not apparent for each enantiomer and internal standard (esomeprazole), the calibration curves were linear over the concentration of 0.500 to 400 ng·mL-1 , the intra-run precisions were below 5.4%, the inter-run precisions were below 9.9%, and the accuracy was between -9.2% and 9.3%. There was no chiral inversion observed during sample storage, preparation procedure, and analysis, demonstrating that analytes were stable in this study. This method was applied to the stereoselective pharmacokinetic study of (R)-(+)- and (S)-(-)-rabeprazole after oral administration of 10-mg rabeprazole sodium enteric-coated tablet in healthy Chinese subjects.

Safety, tolerability, pharmacokinetics and pharmacodynamics of dexlansoprazole injection in healthy Chinese subjects.

PURPOSE: This study was conducted to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of dexlansoprazole injection in healthy subjects. METHODS: Dexlansoprazole (20-90 mg) or lansoprazole (30 mg) was administrated intravenously to healthy male and female volunteers. All the subjects were sampled for pharmacokinetic (PK) analysis and 64 of them were monitored for 24-h intragastric pH prior to and after administration in the pharmacodynamic (PD) study. RESULTS: Maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC0-τ) for dexlansoprazole injection was dose-proportional over the range of 20-90 mg following a single intravenous administration. Total clearance and half-life (t1/2) was independent of dose, and ranged from 4.69 L/h to 5.85 L/h and from 1.24 h to 2.17 h, respectively. A single dose of dexlansoprazole (30 mg) resulted in higher gastric pH compared to that of lansoprazole, evidenced by a mean 24-h gastric pH of 6.1 ± 1.2 (lansoprazole: 5.4 ± 1.1) and 24-h gastric pH > 6 post drug dose holding time of 64.2 ± 21.0% (lansoprazole: 49.5 ± 21.5%). CONCLUSION: Dexlansoprazole injection was safe and well tolerated for up to 5-day repeated intravenous administration dose of 30 mg. The recommended dosage for dexlansoprazole injection is 30 mg for an adequate gastric acid control.