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Aim To develop a liquid chromatography electrospray-ionization tandem mass spectrometry (LC- MS/MS) method for simultaneous determination of bentysrepinine (Y101) and its metabolites M8 and M9 in rat plasma and to investigate the effect of verapamil, an inhibitor of P-glycoprotein (P-gp) , on the pharma¬cokinetics of Y101, a substrate of P-gp, in rats. Methods SD rats were divided randomly into two groups; ( 1) Y101 only as a control group, received an oral dose of 60 mg • kg"1 Y101; (2) Verapamil plus Y101 as an experimental group, received an oral dose of 60 mg • kg"1 Y101 in combination of 25 mg • kg"1 verapamil. The plasma concentrations of Y101 and its metabolites were determined by LC-MS/MS method af¬ter intragastric administration, and the pharmacokinetic parameters were calculated using non-compartmental a- nalysis. Results We successfully developed and fully validated a LC-MS/MS method, which simultaneously determined the concentration of Y101 and its metabo¬lites in rat plasma. The AUC0_t for Y101 and M9 in experimental group increased to 1.71-fold and 1.58- fold in comparison of control group. At the same time, the plasma clearance of Y101 and M9 decreased to 60% of control. However, we did not find any differ¬ence in AUC0_l and plasma clearance for M8 between two groups. Conclusions The validated LC-MS/MS method is sensitive and rapid for the determination of Y101 and its metabolites in rat plasma and was suc¬cessfully applied to the pharmacokinetic study in rats. Verapamil, a P-gp inhibitor, significantly increases the exposure of Y101 and its metabolites in vivo, indicating the adjustment of Y101 dosage for combined adminis¬tration is needed in clinical practice.
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OBJECTIVE： To establish a method for the determination of ibrutinib concentration in Beagle dogs， and to compare the pharmacokinetic difference of ibrutinib and its phospholipid complex in Beagle dogs. METHODS： The male Beagle dogs were randomly divided into Ibrutinib suspension group and Ibrutinib phospholipid complex group （using 0.5％ Carboxymethylcellulose sodium solution and water as solvent， mass concentration of 5 mg/mL）， with 3 dogs in each group. All Beagle dogs were given relevant medicine suspension （15 mg/kg） intragastrically， and 2 mL of blood were collected from the forelimb vein before administration and 0.017， 0.083， 0.25， 0.5， 1， 2， 4， 8 and 12 h after administration. Plasma concentration of ibrutinib was were determined by HPLC. Using tolbutamide as internal standard， the determination was performed on Betasil C18 column with mobile phase consisted of acetonitrile-water （contained 0.5％ triethylamine， pH value adjusted to 3.2 with glacial acetic acid）（45 ∶ 55， V/V） at the flow rate of 1.0 mL/min. The detection wavelength was set at 256 nm， and the column temperature was 25 ℃. The sample size was 20 μL. The pharmacokinetic parameters of Beagle dogs in 2 groups were calculated by using DAS 2.1.1 software. The difference of ibrutinib and its phospholipid complex were investigated by t-test. RESULTS： The linear range of ibrutinib was 5-5 000 ng/mL （r＝0.999 8）； lower limit of quantitation was 5 ng/mL； minimum detection limit was 1.3 ng/mL. RSDs of intra-batch and inter-batch were lower than 10％； the accuracy was 98.81％-106.20％； the extraction method did not influence the determination of the substance to be measured. Pharmacokinetic parameters of Ibrutinib suspension and Ibrutinib phospholipid complex with signal intragastric administration were as follows： tmax were（2.00±0.09） and （0.25±0.03）h； cmax were（610.67±21.36） and （2 308.72±100.41）ng/mL； AUC0-12 h were （4 516.67±383.43） and （9 394.16±874.21）ng·h/mL； AUC0-∞ were （6 174.32±525.27） and （10 717.33±897.62）ng·h/mL，with statistical significance （P＜0.05）. The relative bioavailability of Ibrutinib phospholipid complex was 207.99％. CONCLUSIONS： Established HPLC method is simple， specific and sensitive， and can be used for plasma concentration determination and pharmacokinetic study of ibrutinib. The pharmacokinetic parameters of phospholipid complex prepared from ibrutinib changed significantly， drug absorption is accelerated and bioavailability is improved significantly.
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Aim To evaluate the correlation between in vitro release and in vivo absorption of azithromycin cat-ionic micron niosomes (ACMNS)by Wagner-Nelson method and deconvolution method. Methods The in vitro release behavior of ACMNS was studied by dy-namic membrane dialysis. After a single dose of intra-gastric administration with ACMNS and AM in rats,the AM concentrations in plasma were determined by high performance liquid chromatography(HPLC). Wagner-Nelson and deconvolution method were used to reveal the in vitro / in vivo correlation. Results X used as cu-mulative in vitro release and Fa as the absorption per-centage,the regression equation was established:F a =3. 0524X - 5. 7709,r = 0. 8976,and X used as cumu-lative in vitro release and R as input function,the re-gression equation was established:R = 2. 3413X -58. 687,r = 0. 5217. r < r( 2,0. 05) = 0. 9500 (P <0. 05). Conclusion There is no correlation between in vitro release and in vivo absorption of ACMNS.
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Aim TodevelopandvalidateaLC-MS/MS assay to quantify halometasone in rabbit plasma and study pharmacokinetics of halometasone after dermal topical administration of Halometasone Cream.Meth-ods Theplasmasamplewassubmittedtoliquid-liquid extraction using methyl tertiary butyl ether,with dexa-methasone as the internal standard (IS ).Chromato-graphic separations were performed on a Diamonsil C18 column(100 mm ×4. 6 mm,5 μm)with a linear gra-dient of methanol and 2 mmol · L-1 ammonium ace-tate.Halometasone and dexamethasone(IS)were ion-ized with an ESI source operated in negative ion mode, and the detected ions were m/z 503. 1→413. 0 (halo-metasone),m/z 391. 0→361. 0 (dexamethasone ). The test article could be monitored in rabbit plasma when following single dermal topical administration of Halometasone Cream at 1 g/100 cm2 to rabbits by u-singavalidatedLC-MS/MSassay.Results Calibra-tion curve was linear over the concentration range of0. 02~20 μg·L-1 in rabbit plasma.For low,medi-um,high concentration of QC solutions,the intra-and inter-day precision was in the range of 3. 72% ~7. 87%, and the accuracy was within 99. 1% to 103%. The pharmacokinetic parameters in rabbits were as follows:Tmax,Cmax,AUC0-t,T1/2 was (7. 38 ± 1. 06)h,(1. 16 ±0. 527)μg·L-1,(18. 8 ±7. 23)h·μg·L-1 ,(13. 8 ±3. 70)h,respectively.Conclusions ThisLC-MS/MSanalysismethodhashighsensitivi-ty,and sample processing method is simple,which has been rigorously validated.The method could be suc-cessfully applied to the pharmacokinetic study of halo-metasone after skin administration of Halometasone Cream to rabbits.
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OBJECTIVE To investigate and compare the enzyme kinetic characters of psoralen (PRN)and isopsoralen(IPRN)in rat and human liver microsomes. METHODS PRN and IPRN in liver microsomes incubates were determined using LC-MS/MS. The enzyme kinetic and metabolic stability of PRN and IPRN were investigated by employing the optimized rat and human liver microsomes incubations. The Vmax and Km values were calculated using the nonlinear regression method. RESULTS The quanti?tative method showed good linearity within the range of 0.1-50.0 μmol · L-1 and was suitable for the assay in biological samples. The in vitro elimination was linear with the substrate concentrations lower than 1 μmol,the protein concentration within 0.5 g · L-1,and the incubation time within 40 min. The t1/2 values of PRN and IPRN in rat and human liver microsomes were 74.5,95.0,74.5 and 173.3 min, respectively. The Vmax values of PRN in rat and human liver microsomes were(1.140±0.080)μmol·min-1·g-1 protein,(0.620±0.060)μmol·min-1·g-1 protein,while Km values of PRN in rat and human liver microsomes were (12.9 ± 0.3)μmol · L- 1,(7.4 ± 1.3)μmol · L- 1,respectively. The Vmax values of IPRN in rat and human liver microsomes were(0.251±0.012)and(0.103±0.014)μmol·min-1·g-1 protein,while Km values of IPRN in rat and human liver microsomes were (3.0 ± 0.4)μmol · L-1,(3.4 ± 0.7)μmol · L-1,respectively. CONCLUSION The enzyme kinetic characters and metabolic stability of PRN and IPRN show species and chemical structures related differences. Interestingly,the metabolic eliminations of PRN and IPRN are similar in rats. However,the metabolic elimination of IPRN in humans involved in CYP enzymes may be much slower than that of PRN.
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A simple, rapid and sensitive method for reversed phase HPLC determination of N-acetyl-L-tryptophan (N-ATRP) and its metabolite L-tryptophan (TRP) in rabbit serum was developed based on their intrinsic fluorescence using excitation and emission wavelengths of 280 and 360 nm, respectively. The separation of two amino acids was achieved on an ODS C18 column with a mobile phase of 0. 1 mol ?L-1 NaAc-25% methanol (pH 5. 7) at a flow rate of 0. 5 ml ?min-1. The calibration curves for N-A-TRP and TRP provided the linear range about1.0 - 17. 0mg ?L-1(r=0. 9962 and 0.9978, respectively). The recoveries greater than 98% and good reproducibility were achieved with rabbit serum. The concentration-time curve of N-ATRP after iv administration was determined in rabbits. Results showed that N-ATRP was quickly converted to TRP with a half-life of 8. 5 min. The decrese of N-ATRP accorded well with the rise of TRP.