[show abstract][hide abstract] ABSTRACT: Aim:To investigate the metabolism of GLS4, a heteroaryldihydropyrimidine compound with anti-hepatitis B virus activity, in dog and human liver microsomes in vitro and evaluate the effects of ketoconazole (a potent CYP3A inhibitor) or rifampicin (a potent CYP3A inducer) on GLS4 pharmacokinetics in dogs.Methods:Dog and human liver microsomes and CYP3A4 were incubated with [(14)C]GLS4 for 15 min and then analyzed using a HPLC-dynamic online radio flow detection method. Two groups of beagle dogs were used for in vivo studies. Group A were orally administered a single dose of GLS4 (15 mg/kg) with or without ketoconazole pretreatment (100 mg/d for 8 consecutive days). Group B were orally administered a single dose of GLS4 (15 mg/kg) with or without rifampicin pretreatment (100 mg/d for 8 consecutive days). Plasma was sampled after GLS4 dosing. GLS4 concentrations were determined by HPLC-tandem mass spectrometry.Results:The metabolic profile of [(14)C]GLS4 in human and dog liver microsomes and CYP3A4 was similar. The major metabolites were morpholine N-dealkylated GLS4 and morpholine N,N-di-dealkylated GLS4. Pretreatment with ketoconazole or rifampicin significantly affected the plasma concentrations of GLS4 in dogs: ketoconazole increased the area under the concentration-time curve from 0 to infinity and peak concentration of GLS4 by 4.4 and 3.3 folds, respectively, whereas rifampicin decreased these parameters by 88.5% and 83.2%, respectively.Conclusion:GLS4 is a sensitive substrate of CYP3A. CYP3A inhibitors or inducers cause considerable change of GLS4 plasma concentrations in dogs, which should be considered in clinical practice.
[show abstract][hide abstract] ABSTRACT: Human protein tyrosine kinases play an essential role in carcinogenesis and have been recognized as promising drug targets. By the end of 2012, eight small molecule tyrosine kinase inhibitors (TKIs) have been approved by State Food and Drug Administration of China for cancer treatment. In this paper, the pharmacokinetic characteristics (absorption, distribution, metabolism and excretion) and drug-drug interactions of the approved TKIs are reviewed. Overall, these TKIs reach their peak plasma concentrations relatively fast; are extensively distributed and highly protein bound (> 90%); are primarily metabolized by CYP3A4; most are heavily influenced by CYP3A4 inhibitors or inducers except for sorafenib; are mainly excreted with feces and only a minor fraction is eliminated with the urine; and are substrate of the efflux transporters ABCB1 (P-gp) and ABCG2 (BCRP). Additionally, many of the TKIs can inhibit some CYP450 enzymes, UGT enzymes, and transporters. Gefitinib, erlotinib, dasatinib, and sunitinib are metabolized to form reactive metabolites capable of covalently binding to biomolecules.
Yao xue xue bao = Acta pharmaceutica Sinica 07/2013; 48(7):1080-90.
[show abstract][hide abstract] ABSTRACT: A simple, sensitive, selective, and reproducible liquid chromatography-tandem mass spectrometric method was developed for the simultaneous determination of repaglinide and metformin in human plasma using d5-repaglinide and d6-metformin as internal standards (ISs). After a simple protein precipitation using acetonitrile as the precipitation solvent, both analytes and ISs were separated on a Venusil ASB C 18 (150 mm x 4.6 mm, 5 microm) via gradient elution using acetonitrile--10 mmol x L(-1) ammonium acetate as the mobile phase. A chromatographic total run time of 7.5 min was achieved. Mass spectrometric detection was conducted with atmospheric pressure chemical ionization under positive-ion and multiple-reaction monitoring modes. The method was linear over the 0.2 to 60.0 ng x mL(-1) concentration range for repaglinide and over the 4 to 1 000 ng x mL(-1) range for metformin. For both analytes, the intra- and inter-accuracies and precisions were within the +/- 15% acceptable limit across all concentrations. The validated method was successfully applied to a clinical bioequivalence study.
Yao xue xue bao = Acta pharmaceutica Sinica 04/2013; 48(4):547-53.
[show abstract][hide abstract] ABSTRACT: A sensitive, rapid and accurate liquid chromatography-tandem mass spectrometric (LC-MS/MS) method with pre-column derivatization was developed for the simultaneous determination of erdosteine and its thiol-containing active metabolite in human plasma. Paracetamol and captopril were chosen as the internal standard of erdosteine and its active metabolite, respectively. Aliquots of 100 microL plasma sample were derivatized by 2-bromine-3'-methoxy acetophenone, then separated on an Agilent XDB-C18 (50 mm x 4.6 mm ID, 1.8 microm) column using 0.1% formic acid methanol--0.1% formic acid 5 mmol x L(-1) ammonium acetate as mobile phase, in a gradient mode. Detection of erdosteine and its active metabolite were achieved by ESI MS/MS in the positive ion mode. The linear calibration curves for erdosteine and its active metabolite were obtained in the concentration ranges of 5-3 000 ng x mL(-1) and 5-10 000 ng x mL(-1), respectively. The lower limit of quantification of erdosteine and its active metabolite were both 5.00 ng x mL(-1). The pharmacokinetic results of erdosteine and its thiol-containing active metabolite showed that the area under curve (AUC) of the thiol-containing active metabolite was 6.2 times of that of erdosteine after a single oral dose of 600 mg erdosteine tables in 32 healthy volunteers, The mean residence time (MRT) of the thiol-containing active metabolite was (7.51 +/- 0.788) h, which provided a pharmacokinetic basis for the rational dosage regimen.
Yao xue xue bao = Acta pharmaceutica Sinica 03/2013; 48(3):395-400.
[show abstract][hide abstract] ABSTRACT: Liver is regarded as one of the most important organs for drug clearance in the body, which mediates both the metabolism and biliary excretion of drugs. Transporters are a class of functional membrane proteins and control the movement of substances into or out of cells. Transporters, which are extensively expressed in the liver, play important roles in the drug hepatic disposition by regulating the uptake of drugs from blood into hepatocytes or the efflux of drugs and their metabolites into bile. In this review, the localization, functions and substrate selectivity of the major transporters in the liver will be summarized, and the impacts of these transporters on drug hepatic disposition, the potential drug-drug interactions as well as their genetic polymorphisms will also be reviewed.
Yao xue xue bao = Acta pharmaceutica Sinica 05/2012; 47(5):565-72.
[show abstract][hide abstract] ABSTRACT: To investigate the potential of houttuynin to covalently bind to proteins in vitro and in vivo and to identify the adduct structures.
Male Sprague-Dawley rats were intravenously injected with sodium houttuyfonate (10 mg/kg). The concentrations of houttuynin in blood, plasma and five tissues tested were determined using an LC/MS/MS method. The covalent binding values of houttuynin with hemoglobin, plasma and tissue proteins were measured in rats after intravenous injection of [1-(14)C]sodium houttuyfonate (10 mg/kg, 150 mCi/kg). Human serum albumin was used as model protein to identify the modification site(s) and structure(s) through enzymatic digestion and LC/MS(n) analysis.
The drug was widely distributed 10 min after intravenous injection. The lungs were the preferred site for disposition, followed by the heart and kidneys with significantly higher concentrations than that in the plasma. The extent of covalent binding was correlated with the respective concentrations in the tissues, ranging from 1137 nmol/g protein in lung to 266 nmol/g protein in liver. Houttuynin reacted primarily with arginine residues in human serum albumin to form a pyrimidine adduct at 1:1 molar ratio. The same adduct was detected in rat lungs digested by pronase E.
This study showed that the β-keto aldehyde moiety in houttuynin is strongly electrophilic and readily confers covalent binding to tissue proteins, especially lung proteins, by a Schiff's base mechanism. The findings explain partially the idiosyncratic reactions of houttuyniae injection in clinical use.
[show abstract][hide abstract] ABSTRACT: To compare the bioequivalence and pharmacokinetics of national made and imported atorvastatin in healthy male Chinese volunteers after single oral administration.
This randomized sequence, open-label, two-period crossover study with a one-week washout period between doses was performed in 24 fasting healthy Chinese males. They were randomly assigned to receive 20 mg of either the test (national made) or reference (imported) formulation orally. The blood samples were collected over a 72-hour period. Plasma concentrations of parent atorvastatin (AT), ortho-hydroxy-atorvastatin (o-OAT) and para-hydroxy-atorvastatin (p-OAT) were simultaneously determined using the validated liquid chromatography-tandem mass spectrometry method, the bioequivalence was also evaluated throughout the study.
The main pharmacokinetic parameters of test and reference formulations were as follows: the values of C(max) for AT were (10.6 ± 11.9) µg/L and (10.6 ± 9.8) µg/L, t(1/2z) were (11.4 ± 3.9) h and (11.4 ± 5.3) h, AUC(0-t) were (54.2 ± 37.4) µg×h(-1)×L(-1) and (51.7 ± 34.1) µg×h(-1)×L(-1), respectively. The values of C(max) for o-OAT were (7.8 ± 4.5) µg/L and (7.6 ± 4.3) µg/L, t(1/2z) were (12.3 ± 4.2) h and (11.9 ± 3.4) h, AUC(0-t) were (96.8 ± 48.2) µg×h(-1)×L(-1) and (92.3 ± 44.4) µg×h(-1)×L(-1), respectively. The values of C(max) for p-OAT were (0.5 ± 0.4) µg/L and (0.4 ± 0.3) µg/L, t(1/2z) were (18.4 ± 12.4) h and (23.3 ± 17.8) h, AUC(0-t) were (15.9 ± 12.3) µg×h(-1)×L(-1) and (13.8 ± 8.11) µg×h(-1)×L(-1), respectively. The relative bioavailability of AT and o-OAT in test formulation were (105.3 ± 20.7)% and (107.8 ± 23.2)%, respectively. The 90% confidence interval of the test/reference geometric mean ratios of AUC(0-t) for AT and o-OAT were (97.7 - 110.5)% and (98.3 - 111.3)%, C(max) for AT and o-OAT were (75.8 - 114.0)% and (90.6 - 122.9)%, they were all located within the bioequivalence criteria range (80% - 125% for AUC, and 70% - 143% for C(max)).
The result demonstrated that two formulations were bioequivalent.
Zhonghua xin xue guan bing za zhi [Chinese journal of cardiovascular diseases] 03/2012; 40(3):243-7.
[show abstract][hide abstract] ABSTRACT: Glucagon-like peptide-1 (GLP-1)-based therapy presents a promising option for treating type 2 diabetes. However, there are several limitations relative to the peptidic GLP-1 mimetics currently on the market or under development. This concern has led to a continued interest in the search for non-peptidic agonists for GLP-1 receptor (GLP-1R). Here, we briefly review the discovery, characterization and current status of a novel class of cyclobutane-derivative-based non-peptidic agonists for GLP-1R, including Boc5 and its newly discovered analogue WB4-24. Although the oral bioavailability of such compounds still poses great challenges, the progress made so far encourages us to identify a truly 'druggable' small molecule agonist for GLP-1R.
[show abstract][hide abstract] ABSTRACT: To study the drug-drug interaction of morinidazole and warfarin and its application, a sensitive and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of R-warfarin/S-warfarin in human plasma. In a random, two-period crossover study, 12 healthy volunteers received a single oral dose of 5 mg racemic warfarin in the absence and presence of morinidazole. Blood samples were collected according to a pre-designed time schedule. R-warfarin, S-warfarin and methyclothiazide were extracted with ethylether : methylenechloride (3 : 2), then separated on a Astec Chirobiotic V (150 mm x 4.6 mm ID, 5 microm) column using 5 mmol x L(-1) ammonium acetate (pH 4.0) - acetonitrile as mobile phase at a flow-rate of 1.5 mL x min(-1). The mobile phase was splitted and 0.5 mL x min(-1) was introduced into MS. A tandem mass spectrometer equipped with electrospray ionization source was used as detector and operated in the negative ion mode. Quantification was performed using multiple reaction monitoring (MRM). The resolution of warfarin enantiomers is 1.56. The linear calibration curves for R-warfarin and S-warfarin both were obtained in the concentration range of 5 - 1 000 ng x mL(-1). Intra- and inter-day relative standard deviation (RSD) for R-warfarin and S-warfarin over the entire concentration range across three validation runs was both less than 10%, and relative error (RE) ranged from -4.9% to 0.7%, separately. The method herein described is effective and convenient, and suitable for the study of metabolic interaction between morinidazole and warfarin. The results showed that coadministration of warfarin with morinidazole did not affect the pharmacokinetics of either R-warfarin or S-warfarin.
Yao xue xue bao = Acta pharmaceutica Sinica 01/2012; 47(1):105-9.
[show abstract][hide abstract] ABSTRACT: To evaluate the pharmacokinetics of tacrolimus in Chinese stable liver transplant recipients converted from immediate release (IR) tacrolimus-based immunosuppression to modified release (MR) tacrolimus-based immunosuppression.
Open-label, multi-center study with a one-way conversion design was conducted. Eighty-three stable liver recipients (6-24 months post-transplant) with normal renal and stable hepatic function were converted from IR tacrolimus twice-daily treatment to MR tacrolimus once-daily treatment on a 1:1 (mg: mg) total daily dose basis. Twenty-four hour pharmacokinetic studies were carried out on d 0 (pre-conversion), d 1, and d 84 (post-conversion).
The area under the blood concentration-time curve of MR tacrolimus from 0 to 24 h (AUC(0-24)) on d 1 was comparable to that of IR tacrolimus on d 0, with a 90% confidence interval (CI) for MR/IR tacrolimus of 92%-97%. The AUC(0-24) value for MR tacrolimus on d 84 with the daily dose increased by 14% was approximately 17% lower than that for IR tacrolimus. The 90% CI was 77%-90%, outside the bioequivalence range of 80%-125%. There was a good correlation between AUC(0-24) and concentration at 24 h (C(24)) for IR tacrolimus (d 0, r=0.930) and MR tacrolimus (d 1, r=0.936; d 84, r=0.903).
The exposure to tacrolimus when administered MR tacrolimus once daily is not equivalent to that for IR tacrolimus twice daily after an 84-day conversion in Chinese stable liver transplant recipients. The dose should be adjusted on the basis of trough levels. The therapeutic drug monitoring for patients treated with IR tacrolimus is considered to be applicable to MR tacrolimus.
[show abstract][hide abstract] ABSTRACT: Chlorogenic acid (5-CQA) is one of the major components in some Chinese herbal injections. However, the metabolism of 5-CQA in rats after intravenous injection has not been determined. An ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) method was applied to identify the metabolites in bile, urine, feces and plasma after a single intravenous administration of 10 mg x kg(-1) 5-CQA to rats. Using MSE and mass defect filter techniques, a total of 35 metabolites were detected in bile, urine, feces and plasma. The predominant metabolites in bile were glutathione conjugates of O-methyl-5-CQA, accounting for approximately 80% of the metabolites excreted in bile. The major components in urine were parent drug, O-methyl-5-CQA, hydrolyzed metabolites and glucuronide conjugates. The major components in feces were O-methyl-5-CQA and its cysteine conjugates. The major component in plasma was the parent drug. The urinary and fecal excretion pathways were equally important to 5-CQA in rats. These results demonstrate that 5-CQA undergoes extensively metabolism in rats and are highly reactive to nucleophiles such as GSH. This finding indicates that attention should be paid on the injections containing 5-CQA, which may covalently bind to proteins, leading to allergenic drug reactions.
Yao xue xue bao = Acta pharmaceutica Sinica 01/2011; 46(1):88-95.
[show abstract][hide abstract] ABSTRACT: Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.
Journal of Neuroscience 04/2010; 30(14):5058-70. · 6.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: To study the effects of CYP2C9 and CYP2C19 genetic polymorphisms on the pharmacokinetics and pharmacodynamics of glipizide.
Eighteen healthy male subjects were divided into three groups according to their genotypes: group I, CYP2C9*1/*1 and CYP2C19 extensive metabolizers (EMs); group II, CYP2C9*1/*1 and CYP2C19 poor metabolizers (PMs); and group III, CYP2C9*1/*3 and CYP2C19 EMs. After a single dose of a 5-mg glipizide tablet, plasma concentrations of glipizide for a 36-h period were determined. Meanwhile, plasma glucose levels and plasma insulin levels were determined from 0 to 4 h after dosing.
The area under the plasma concentration-time curve (AUC(0-infinity)) was 2.0-fold higher and the oral clearance was 51.1% lower in group III than in group I. The change in fasting insulin level within 1 h (DeltaAUEC(insulin0-1h)) in group III was 3.8-fold higher than that in group I. The glipizide parameters in group II exhibited similar tendencies to those in group III.
These results suggest that CYP2C9 polymorphism significantly influences the pharmacokinetics and pharmacodynamics of glipizide, which needs to be considered in clinical practice. CYP2C19 polymorphism exhibits a tendency to influence the effects of glipizide, to a certain extent similarly to CYP2C9 polymorphism.
European Journal of Clinical Pharmacology 10/2009; 66(2):145-51. · 2.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: The potential for topical delivery of meloxicam was investigated by examining its pharmacokinetic profiles in plasma and synovial fluid following oral and transdermal administration in Beagle dogs.
The experiment was a two-period, crossover design using 6 Beagle dogs. Meloxicam tablets were administered orally at a dose of 0.31 mg/kg, and meloxicam gel was administered transdermally at a dose of 1.25 mg/kg. Drug concentrations in plasma and synovial fluid were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pharmacokinetic parameters were calculated using the Topfit 2.0 program.
The pharmacokinetic results showed that AUC(0-t) (23.9+/-8.26 microg.h.mL(-1)) in plasma after oral administration was significantly higher than after transdermal delivery (1.00+/-0.43 microg.h.mL(-1)). In contrast, the ratio of the average concentration in synovial fluid to that in plasma following transdermal administration was higher than that for an oral delivery. The synovial fluid concentration in the treated leg was much higher than that in the untreated leg, whereas the synovial fluid concentration in the untreated leg was similar to the plasma concentration.
The high concentration ratio of synovial fluid to plasma indicates direct penetration of meloxicam following topical administration to the target tissue. This finding is further supported by the differences observed in meloxicam concentrations in synovial fluid in the treated and untreated joints at the same time point. Our results suggest that transdermal delivery of meloxicam is a promising method for decreasing its adverse systemic effects.Acta Pharmacologica Sinica (2009) 30: 1060-1064; doi: 10.1038/aps.2009.73; published online 8 June 2009.
[show abstract][hide abstract] ABSTRACT: This paper is aimed to develop rapid, sensitive and convenient HPLC-MS/MS methods for the quantification of levosimendan and its metabolites OR-1855 and OR-1896 in human plasma. According to the different natures of the compounds, two sets of liquid chromatography and ionization modes were used for determination the concentration of levosimendan and its metabolites OR-1855 and OR-1896 in human plasma, separately. Following protein precipitation with methanol, the levosimendan and internal standard (rosuvastatin) were separated on a Capcell MG III C18 column (35 mm x 2.0 mm ID, 3 microm) with the mobile phase consisted of methanol-15 mmol x L(-1) ammonium acetate-formic acid (55: 45: 0.02, v/v/v). A tandem mass spectrometer equipped with electrospray ionization source was used as the detector and operated in the negative ion mode. Its metabolites OR-1855, OR-1896 and internal standard doxofylline were extracted from plasma by liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a Zorbax Extend C18 column (150 mm x 4.6 mm ID, 5 microm) with the mobile phase consisted of methanol-15 mmol x L(-1) ammonium acetate-formic acid (65 :35 :0.1, v/v/v). A tandem mass spectrometer equipped with electrospray ionization source was used as the detector and operated at the positive ion mode. The linear concentration ranges of the calibration curves for levosimendan and OR-1855 and OR-1896 were 0.10-50.0 ng x mL(-1), 0.20-100 ng x mL(-1), 0.20-100 ng x mL(-1), respectively. The lower limits of quantification of levosimendan and OR-1855 and OR-1896 were 0.10 ng x mL(-1), 0.20 ng x mL(-1), 0.20 ng x mL(-1), respectively. The methods proved to be sensitive, simple and rapid, and suitable for the pharmacokinetic study of levosimendan injection.
Yao xue xue bao = Acta pharmaceutica Sinica 11/2008; 43(10):1053-9.
[show abstract][hide abstract] ABSTRACT: With homology modeling techniques, a 3D structure model of CYP2C19 was built and refined with molecular mechanics and molecular dynamics simulations. The refined model was assessed to be reasonable by Profile-3D and PROCHECK programs. With the aid of the automatic molecular docking, one substrate and two inhibitors were docked to CYP2C19 by InsightII/Affinity program. The docking results, which are in well agreement with the reported results, demonstrate that the refined model of CYP2C19 is reliable. Then, with the refined model of CYP2C19 and the crystal structure of CYP2C9, the metabolisms of them for gliclazide in two different metabolic pathways were studied and the results show that both enzymes have more favorable interaction energies and stronger affinity with gliclazide in methylhydroxylation pathway than in 6beta-hydroxylation pathway. It is exciting that substrate inhibition phenomenon can be found in metabolisms of CYP2C9 and CYP2C19 for gliclazide in two metabolic pathways. Gliclazide can change the conformation of the active sites and decrease obviously the affinities between gliclazide in the active site and enzymes when it is docked in the second active sites in CYP2C9 and CYP2C19. These results are in well agreement with the kinetic experimental results.
European journal of medicinal chemistry 06/2008; 44(2):854-61. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: A liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of budesonide in dog plasma. Budesonide and the internal standard triamcinolone acetonide were separated from plasma by alkalinized liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a Capcell Pak C18 MG column with the mobile phase consisted of acetonitrile -5 mmol x L(-1) ammonium acetate (60:40, v/v) at a flow-rate of 0.50 mL x min(-1). A tandem mass spectrometer equipped with electrospray ionization source was used as detector and operated in the negative ion mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 489 --> m/z 357 and m/z 493 --> m/z 413 for budesonide and the internal standard, respectively. The linear calibration curves were obtained in the concentration range of 25.0-2000 pg x mL(-1). The lower limit of quantification was 25.0 pg x mL(-1). The intra- and inter-day relative standard deviation over the entire concentration range was less than 15%. The accuracy was in the range of -8.1% to -1.7% in terms of relative error. The method was applied to a pharmacokinetic study of budesonide controlled-release capsules in Beagle dogs. Maximal budesonide plasma level was observed after (3.5 +/- 3.3) h and the Cmax was (786 +/- 498) pg x mL(-1) after a single oral administration of 9 mg budesonide capsules, Cmax was increased to (2142 +/- 1515) pg x mL(-1) after multiple oral administration (9 mg x 5 d) of budesonide capsules. This method was selective and rapid, and the sensitivity was sufficient for the purpose of the pharmacokinetic study of budesonide controlled-release formulation.
Yao xue xue bao = Acta pharmaceutica Sinica 01/2008; 43(1):76-80.
[show abstract][hide abstract] ABSTRACT: To investigate the pharmacokinetics of clarithromycin citrate salt and the effect of food on the absorption of free base and citrate salt, clarithromycin citrate was prepared and the in vitro intrinsic dissolution profiles of the free base and the salt were examined at pH 5.0 and pH 6.8. The pharmacokinetic profiles of clarithromycin following a single oral administration as the free base and its citrate salt (equivalent to 75 mg clarithromycin) were evaluated in eight beagle dogs. The plasma concentrations of clarithromycin were determined by reversed-phase liquid chromatography coupled to tandem mass with positive ion electrospray ionization using the multiple reaction monitoring method. The dissolution rates of clarithromycin and its citrate salt were similar at pH 5.0; however, at pH 6.8 citrate salt significantly enhanced the dissolution rate of clarithromycin. Clarithromycin's relative bioavailability value as expressed by the ratio of total mean area under the curve for clarithromycin citrate to that of clarithromycin was 104.2% and 110.1% under fast and fed conditions, respectively. The clarithromycin plasma area under the curve ratio was 33.4% and 25.7%, respectively, following oral clarithromycin or clarithromycin citrate salt drug coadministration with breakfast compared to fast-state controls (P < 0.05). There was no difference in pharmacokinetic parameters between clarithromycin and clarithromycin citrate salt under fast and fed conditions, but under the fed condition, T(max) was delayed and the C(max) of clarithromycin citrate salt and clarithromycin was decreased relative to the fasted condition, indicating that the consumption of this meal substantially reduced the drug's bioavailability.
PDA journal of pharmaceutical science and technology / PDA 01/2008; 62(6):445-53.
[show abstract][hide abstract] ABSTRACT: Accurate mass measurements of 20 drugs were conducted using MassWorks software on a TSQ Quantum Ultra mass spectrometer. All Q1 scan mass spectral data were collected in profile mode with full width at half-maximum (FWHM) set at 0.7 Da. The mass errors of all 20 drugs (molecular weight between 135 and 810) were within the range from -22.4 x 10(-6) to 36. 1 x 10(-6), among them 90% of the drugs achieved a mass accuracy better than 10 x 10(-6). The new method can provide accurate mass measurements on unit mass resolution mass spectrometers.
Yao xue xue bao = Acta pharmaceutica Sinica 11/2007; 42(10):1112-4.
[show abstract][hide abstract] ABSTRACT: To develop a sensitive and rapid liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for simultaneous quantitation of metformin and glipizide in human plasma, metformin, glipizide and internal standard diphenhydramine were separated from plasma by protein precipitation with acetonitrile (containing 0.3% formic acid), then chromatographed by using a Zorbax Extend C18 column. The mobile phase consisted of acetonitrile-water-formic acid (70:30: 0.3, v/v/v), at a flow rate of 0.50 mL x min(-1). A tandem mass spectrometer equipped with atmospheric pressure chemical ionization source was used as detector and operated in the positive ion mode. Selected reaction monitoring (SRM) using the precursor/production combinations of m/z 130-->m/z 60, m/z 446-->m/z 321 and m/z 256-->m/z 167 were used to quantify metformin, glipizide and diphenhydramine, respectively. The linear concentration ranges of the calibration curves for metformin and glipizide were 2.00 - 2000 ng x mL(-1) and 1.00 - 1000 ng x mL(-1), respectively. The lower limits of quantitation of metformin and glipizide were 2.00 ng x mL(-1) and 1.00 ng x mL(-1), respectively. The method proved to be sensitive, simple and rapid, and suitable for clinical investigation of compound preparation containing metformin and glipizide.
Yao xue xue bao = Acta pharmaceutica Sinica 11/2007; 42(10):1087-91.