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??OBJECTIVE To establish a LC-MS/MS method for determining F1 in rat plasma and study the pharmacokinetic properties of F1. METHODS Ten healthy SD rats were enrolled in this study. They were randomly divided into two groups and received intragastric(10 mg??kg^-1) and intravenous administration(5 mg??kg^-1) of F1. After receiving F1, the concentrations of F1 in plasma were determined. Blood samples(0.1 mL)were immediately collected into heparinized tubes before injection and at 0,0.08, 0.25,0.5,0.75,1,2,4,6,8,10,12,24 h after injection. The pharmacokinetic parameters were determined by DAS2.0 software, absolute bioavailability of F1 was calculated based on AUC and dose administered. RESULTS The main pharmacokinetic parameters after intragastric and intravenous administration of F1 were as follows: ACU_0-t(27.052??10.068),(153.878??88.777)ng??h??mL^-1;AUC_0-??(31.425??9.261),(179.054??116.794)ng??h??mL^-1;MRT_0-t(10.722??4.335), (2.398??1.344)h; MRT_0-?? (15.651??5.917),(6.925??7.013)h;t_1/2(4.294??1.534),(6.052??3.633)h;??_max(18.394??17.856),(219.079??142.207)ng??mL^-1,respectively. Absolute bioavailability value was 8.79%. CONCLUSION This method can be used to determine the content of F1 in rat plasma. The experimental results can guide the structural optimization of F1, improve the pharmacokinetics of F1 in vivo and provide experimental basis for improving bioavailability of F1.     

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??OBJECTIVE To investigate the influence of tripterygium glucoside tablet on the pharmacokinetics of atorvastatin in rats. METHODS Twelve rats were equally randomized to two groups (six rats in each group), including the atorvastatin-only group (A) and the tripterygium glucoside tablet and atorvastatin group (B). Animals in group A were administered according the oral dose of 2 mg??kg^-1; and animals in group B were administered at an oral dose of atorvastatin (2 mg??kg^-1)and tripterygium glucoside tablet (2 mg??kg^-1). Blood samples were collected into a heparinized tube via the oculi chorioideae vein at different time points after drug administration, and the plasma concentration of atorvastatin were determined using HPLC-UV. Finally, the pharmacokinetic profiles of atorvastatin were calculated and compared. RESULTS Compared with the atorvastatin-only group(A), the pharmacokinetic parameters of the tripterygium glucoside tablet and atorvastatin group(B) have changed greatly. ??_max of atorvastatin increased from (4.77??0.64) to (7.79??0.61) mg??L^-1, and AUC_0-t increased from (12.82?? 3.50) to (27.39??5.76) mg??h??L^-1, at the same time, t_max was extended from (0.25??0.03) to (0.52??0.07) h, t_1/2 was prolonged from (2.39??0.19) to (5.09??1.35) h, MRT was extended from (2.93??0.23) to (4.36??0.44)h. It indicates that the metabolism of atorvastatin may be suppressed. CONCLUSION The RESULTS indicate that tripterygium glucoside tablet could influence the pharmacokinetics of atorvastatin when atorvastatin and tripterygium glucoside tablet are used concomitantly. This study could be used for clinical medication guidance of tripterygium glucoside tablet and atorvastatin to avoid the occurrence of adverse reactions.     

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??OBJECTIVE To assess the impact of chrysin and naringenin on the pharmacokinetics (PK) of saquinavir (SQV), a substrate of P-glycoprotein (P-gp), in rats. METHODS Fifteen rats were randomized into 3 groups of equal size, and administered orally 30 mg??kg^-1 SQV with or without 40 mg??kg^-1 chrysin or naringenin. The PK of SQV was assessed using non-compartmental analysis and the plasma concentrations of three groups were determined by LC-MS/MS. RESULTS The PK parameters values of SQV, SQV+ naringenin, SQV+ chrysin are as follows:AUC_0-t,882.91,861.32,934.84 ng??h??mL^-1; AUC_0-??,903.97,865.90,947.92 ng??h??mL^-1; ??_max,177.72,89.8,130.72 ng??mL^-1; t_max,1,2,0.5 h;t_1/2,11.73,12.61,13.33 h; MRT_0-??,27.09,31.63,26.60 h; CL/F,21.65,21.45,20.62 mL??kg^-1??h^-1. CONCLUSION Double peak phenomenon is observed in the plasma SQV profiles. Our study demonstrates that chrysin and naringenin can not significantly affect the SQV oral bioavailability and SQV PK profiles in rats.     

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??OBJECTIVE To study the pharmacokinetics of hot-melt spray-dried andrographolide granules and compare it with andrographolide bulk drug. METHODS A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for determination of the concentration of andrographolide in plasma of rats which were respectively given micronized andrographolide and hot-melt spray-dried andrographolide granules, then the pharmacokinetic parameters were calculated. RESULTS The pharmacokinetic parameters of andrographolide after a single dose administration of micronized andrographolide and hot-melt andrographolide were as following: t_1/2 were (347.33??9.32) and (390.82??8.78) min, t_max were (30.00??5.94) and (60.00??3.48) min, ??_max were (1 940.14??21.21) and (1 818.22??23.64) ng??mL^-1, AUC_0-t were (427 515.71??37 350.03) and (426 406.31??20 577.75) ng??min??mL^-1, AUC_0-inf were (545 423.14??47 969.18) and (593 569.87??30 247.35) ng??min??mL^-1, Vz/F were (43.48??4.75) and (44.96??3.81) kg??L^-1, CL/F were (86.78??3.35) and (79.74??2.89) kg??L^-1??min^-1, respectively. CONCLUSION Compared with the bulk drug, the hot-melt spray-dried andrographolide granules have a longer t_1/2, lower ??_max and delayed t_max in rats.     

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??OBJECTIVE To establish an HPLC-UV method for the simultaneous determination of valsartan and nifedipine in rats plasma, so as to study the pharmacokinetic interaction between valsartan and nifedipine and to provide useful information for clinical practice. METHODS Eighteen male Wistar rats were divided into three groups: valsartan group(16 mg??kg^-1), nifedipine group (4.2 mg??kg^-1) and combined group (containing valsartan 16 mg??kg^-1, nifedipine 4.2 mg??kg^-1). Plasma samples were collected at 0, 0.08, 0.16, 0.25, 0.5, 0.75, 1, 2, 4, 8, 10, 24 h after the drug administration. An HPLC with UV detection method was developed to determine the concentration of valsartan and nifedipine in rat plasma, and the pharmacokinetic parameters were calculated using non-compartment model. RESULTS Compared with single valsartan group, the pharmacokinetic parameters ??_max and AUC_0-t of the combined group had a significant increase(P<0.05), while Tmax and CLz/F had a significant decrease(P<0.05). Compared with single nifedipine group, the pharmacokinetic parameters t_1/2z/h had a significant decrease(P<0.05), while other pharmacokinetic parameters had no significant differences. CONCLUSION Combination of valsartan and nifedipine could significantly improve the valsartan in rats plasma concentration and bioavailability, increase absorption and decrease excretion , while nifedipine shows no pharmacokinetic change in rats except shortened half-life.     

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??OBJECTIVE To develop an LC-MS/MS method for the quantitative analysis of ocotillol in rat plasma, and study the pharmacokinetic characteristics of ocotillol in rats after oral administration.METHODS Ocotillol was extracted from plasma sample by protein precipitation. The concentration of ocotillol in plasma was determined by LC-MS/MS and the plasma concentration-time curve and main pharmacokinetic parameters were calculated after a single oral administration of ocotillol at 40 mg??kg^-1 to SD rats.RESULTS Excellent linearity was found between 10-240 ng??mL^-1. Intra-and inter-day precision values (RSDs) of QC samples were both below 15% and the extraction recoveries of ocotillol from plasma were higher than 84.14%. Double peaks were observed in the mean plasma concentration versus time profile of ocotillol after oral administration. The main pharmacokinetic parameters of ocotillol were as follows:the mean maximum plasma concentration (??_max) was (156.60??51.84) ng??mL^-1 occurring at (0.83??0.26) h post dose, the mean elimination half-time (t_1/2) was (8.82??7.56) h, and the mean area under the plasma concentration versus time curve (AUC_0-t) was (687.15??144.08) ng??h??mL^-1.CONCLUSION The current data shows that ocotillol is rapidly absorbed in rats after oral administration and slowly eliminated from circulatory blood system, with low plasma exposure. Enterohepatic circulation may contribute to the atypical drug absorption profiles.     

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??OBJECTIVE To establish an LC-MS/MS method for the determination of levetiracetam to investigate the pharmacokinetics of levetiracetam extended-release tablets at fasted and fed states. METHODS The separation was achieved on a Waters Symmetry C₁₈ column (3.9 mm??150 mm,5 ??m) with mobile phase consisting of acetonitrile-5 mmol??L^-1 ammonium acetate and 0.3% formic acid aqueous solution (10/90, V/V). Two subjects were randomly assigned to receive single oral dose of levetiracetam extended-release tablets 1 000 mg after being fasted and fed by a randomized crossover design. The plasma concentrations of levetiracetam were measured by LC-MS/MS. RESULTS The calibration curve of levetiracetam in human plasma was linear over the concentration rang of 0.100 0-80.00 ??g??mL^-1. Under fasted and fed conditions, the main pharmacokinetic parameters of levetiracetam were as follows:??_max were 20.50 and 19.09 ??g??mL^-1, AUC_{0-48 h} were 345.4 and 336.3 ??g??h??mL^-1, t_max were 4.5 and 7.0 h, respectively. CONCLUSION The method is proved to be convenient, accurate and sensitive, and suitable for the pharmacokinetic study of 1 000 mg levetiracetam extended-release tablets in healthy Chinese volunteers after being fasted and fed. The result suggests that high fat and calories diet has effect on the pharmacokinetics of levetiracetam extended-release tablets, with t_max being delayed.     

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??OBJECTIVE To study the pharmacokinetics and bioequivalence of hydroxysafflor yellow A (HSYA) and hydroxysafflor yellow A nanoemulsion (HYAN) in rats.METHODS Twelve male rats were randomly divided into two groups. The rats were administered intragastrically with HSYA or HYAN, respectively, and then blood was collected from the venous plexus at different time points. HPLC method was used for the determination of HSYA blood concentration.RESULTS The main pharmacokinetic parameters of HYAN were as follows: the area under curve (AUC_{0-24 h}), peak concentration (??_max), peak time (t_max) and clearance (CL) were (31.56??4.58) mg??L??h^-1, (12.75??2.64) mg??L^-1, (0.83??0.54) h and (1.89??0.93) L??h^-1??kg^-1, respectively. The AUC_{0-24 h}, ??_max and t_max of HYAN increased by 5.49, 10.22 and 2.50 times, respectively, and the CL of HYAN was only 1/4 of that of HSYA. The 90% confidence intervals for AUC_{0-24 h} and ??_max were not within the prescribed range of bioequivalence criteria.CONCLUSION Relative to HSYA, the high plasma concentration and prolonged peak time of HYAN in vivo can significantly improve the oral bioavailability of HSYA. HSYA solution and HYAN are not bioequivalent.     

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??OBJECTIVE To investigate the effect of high-fat and high-calorie diets on pharmacokinetics of cefuroxime axetil in healthy Chinese subjects. METHODS A randomized, open-label, single dose and two-way crossover clinical study was conducted. Twelve healthy subjects were randomly divided into two groups, each of which includes six males, then they were given 250 mg of cefuroxime axetil respectively before and after meal. Blood samples were collected at different time points before and after drug administration. The concentration of cefuroxime in plasma was determined by HPLC-MS/MS. The pharmacokinetic parameters were calculated by DAS3.2.8 and were analyzed by DAS3.2.8 and SPSS19.0. RESULTS The main pharmacokinetic parameters of fasting and postprandial were as follows: AUC_0-t was (11 402.8??3 556.7) and (18 565.7??2 917.9) ng??h??mL^-1, AUC_0-?? was (11 492.5??3 581.8) and (18 754.7??2 885.6) ng??h??mL^-1, ??_max was (3 406.7??1 188.9) and (5 439.2??1 118.2) ng??mL^-1, t_max was (2.01??0.64) and (2.08??0.79) h, t_1/2 was (1.66??0.38) and (1.60??0.60) h, respectively. The main pharmacokinetic parameters between fasting and high-fat meal groups were analyzed by SPSS19.0 software. There was significant difference in AUC_0-t, AUC_0-?? and ??_max(P<0.01), and no significant difference in t_max and t_1/2 (P>0.05). The ??_max and AUC were increased by 59.7% and 63.2% respectively, t_max is almost unchanged. The equivalence analysis was performed with DAS.3.2.8 software, the 90% confidence intervals for the ratios of AUC_0-t, AUC_0-?? and ??_max for the postprandial/fasting were 137.6%-217.5%, 138.4%-217.3%, 135.4%-207.6%, respectively. None of them fall within the acceptable interval of 80%-125%. CONCLUSION High-fat and high-calorie diets can significantly improve the extent of absorption of cefuroxime axetil in vivo, but does not affect the absorption rate of cefuroxime axetil.     

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??OBJECTIVE To investigate the pharmacokinetics of matrine injection by different routes of administration. METHODS Twenty healthy SD rats were enrolled in this study. They were randomly divided into two groups and received intraperitoneal and intravenous administration of matrine injection at dose of 15 mg??kg^-1 respectively. Blood samples (0.3-0.4 mL) were immediately collected into heparinized tubes before injection and at 0.033, 0.083, 0.167, 0.333, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 12 h after injection. Plasma sample concentrations were determined by a validated LC-MS/MS method. The pharmacokinetic parameters including AUC_0-12, AUC_0-??, MRT_0-12, MRT_0-??, t_1/2, Vd, CL and ??_max were calculated. RESULTS The main pharmacokinetic parameters for matrine after intraperitoneal and intravenous administration at dose of 15 mg??kg^-1 were as follows:AUC_0-12 (10 166??2 426), (12 217??2 968) ng??mL^-1??h;AUC_0-?? (10 230??2 432), (12 300??3 031)- ng??mL^-1??h;MRT_0-12 (1.91??0.41), (2.14??0.54) h;MRT_0-?? (2.01??0.41), (2.26??0.64) h; t_1/2(2.26??0.89), (2.60??1.25) h;Vd(4 998??2 010), (6 175??2 540) mL;CL (1 531??315.0), (1 727??475.6) mL??h^-1??kg^-1; ??_max (5 246??1 187), (8 503??1 101) ng??mL^-1, respectively. The bioavailability of intraperitoneal administration is 83.21%. CONCLUSION No significant differences were observed in AUC, MRT, t_1/2 and CL values of matrine between different administrations except for ??_max and Vd.