The determination of diflucortolone in rabbit plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS) / 药学学报

A sensitive and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantitative determination of diflucortolone in rabbit plasma after dermal administration of diflucortolone valerate cream to rabbits. After extraction with ethyl acetate, the chromatographic separation was performed on Zorbax Eclipse XDB-C18 (50 mm×4.6 mm, 5 μm) with a gradient mobile phase consisting of 50% acetonitrile-50% methanol and 0.1% formic acid-5% methanol-5 mmol·L-1 ammonium formate at a flow rate of 0.35 mL·min-1. The quantitative analysis was carried out using multiple reaction monitoring (MRM) at specific ion transitions of m/z [M+H]+ 395.2→m/z 355.2 for diflucortolone and m/z [M+H]+ 258.1→m/z 120.9 for ethoxyphenylethylamine (internal standard) in positive ion mode with electrospray ionization (ESI) source. This validated LC-MS/MS method had a linearity over the concentration range of 0.01-10 ng·mL-1 with the lower limit of quantification (LLOQ) at 0.01 ng·mL-1. At level of LLOQ, the inter and intra-assay precision (RSD) were no greater than 9.82% and 11.0%, respectively. The main pharmacokinetic parameters of the diflucortolone including tmax, Cmax, AUC0-72 h, and t1/2 were as follows: (6.33±1.21) h, (0.168±0.080 0) ng·mL-1, (3.15±0.834) h·ng·mL-1, (32.0±17.4) h. The method was validated in the pharmacokinetic study of diflucortolone in rabbit following dermal administration of diflucortolone valerate cream at dose of 0.01 g·cm-2. In this study, the program of animal testing had been approved by Committee on the management and usage of experimental animal in the Evaluation Company of Innovative Drug, Tianjin Institute of Pharmaceutical Research.

Determination of obeticholic acid in rat plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS) / 药学学报

A simple and sensitive method was developed for quantitation of obeticholic acid in rat plasma with liquid chromatography-tandem mass spectrometry (LC-MS/MS). After liquid-liquid extraction by methyl tert-butyl ether, the chromatographic separation was carried out on an ACE Excel 2 Super C18 column (50 mm×2.1 mm ID, 1.7 μm) with a gradient mobile phase consisting of acetonitrile and 2 mmol·L-1 ammonium formate at a flow rate of 0.2 mL·min-1. The quantitation analysis was performed using multiple reaction monitoring (MRM) at the specific ion transitions of m/z 418.9[M-H]-→401.2 for obeticholic acid and m/z 469.0[M-H]-→ 425.2 for glycyrrhetinic acid (internal standard) in the negative ion mode with electrospray ionization (ESI) source. This validated LC-MS/MS method yielded a good linearity over the range of 5 -5 000 ng·mL-1 with the lower limit of quantitation (LLOQ) of 5 ng·mL-1. The intra and inter-assay precisions (RSD) were all less than 9.82% and the accuracy (RE) was within ±6.90%. The extraction recovery of obeticholic acid was from 85.4% to 88.5%, and the matrix effect of obeticholic acid ranged from 78.9% to 82.5%. Stability test suggest that obeticholic acid in rat plasma was stable for 24 h on workbench, up to 1 month at -70℃, and after three cycles of freeze-thaw. Extracted samples were stable for more than 24 h in an auto-sampler at 6℃. The precision was less than 7.25%, and the accuracy was within ±11.2%, after being diluted 10 times by blank rat plasma. The method has been successfully applied to a pharmacokinetic study of obeticholic acid in rats following oral administration at the dose of 2.5 mg·kg-1.

Simultaneous determination of salidroside and tyrosol in Beagle dog plasma using UHPLC-MS/MS after pre-column dansyl chloride derivatization / 药学学报

A pre-column derivatization method combined with UHPLC-MS/MS was developed for the simultaneous determination of salidroside and tyrosol in Beagle dog plasma. After protein precipitation by acetonitrile, the liquid supernatant was treated with dansyl chloride under dark conditions at 60℃ for 30 min, and then, the sample solution was extracted using methyl tertiary butyl ether. The multiple reaction monitoring in positive ion mode was used for MS detection of the tested analytes with the specific ion transitions of m/z 534.2→372.0 for salidroside derivative, m/z 372.0→171.0 for tyrosol derivative and m/z 506.0→171.0 for arbutin derivative. The chromatograph separation was achieved on an ACQUITY UPLC® BEH C18 column (100 mm×2.1 mm, 1.7 μm) with a gradient mobile phase consisting of acetonitrile (0.1% formic acid)-water (10% acetonitrile, 0.1% formic acid) for 9 min. The assay showed a good linearity over the range of 0.02/0.1-20/10 μmol·L-1 with a lower limit of quantitation of 0.02 and 0.1 μmol·L-1 for salidroside and tyrosol in dog plasma, respectively. The intra-and inter-day precisions were all less than 8.68%, and the accuracy was within ±11.4%. The established method with a high sensitivity, good specificity and reliability was appropriate for simultaneous determination of salidroside and tyrosol in dog plasma and successfully applied to a pharmacokinetic study after intragastric administration of salidroside to Beagle dogs.

Simultaneous determination of clevidipine butyrate and its metabolite clevidipine acid in dog blood by liquid chromatography-tandem mass spectrometry / 药学学报

A rapid, sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of clevidipine butyrate and its primary metabolite clevidipine acid in dog blood. After one-step protein precipitation with methanol, the chromatographic separation was carried out on an Ecosil C18 column (150 mm x 4.6 mm, 5 µm) with a gradient mobile phase consisting of methanol and 5 mmol · L(-1) ammonium formate. A chromatographic total run time of 13.0 min was achieved. The quantitation analysis was performed using multiple reaction monitoring (MRM) at the specific ion transitions of m/z 454.1 [M-H]- --> m/z 234.1 for clevidipine butyrate, m/z 354.0 [M-H]- --> m/z 208.0 for clevidipine acid and m/z 256.1 [M-H]- --> m/z 227.1 for elofesalamide (internal standard, IS) in the negative ion mode with electrospray ionization (ESI) source. The linear calibration curves for clevidipine butyrate and clevidipine acid were obtained in the concentration ranges of 0.5-100 ng · mL and 1-200 ng · mL(-1), separately. The lower limit of quantification of clevidipine butyrate and clevidipine acid were 0.5 ng · mL(-1) and 1 ng · mL(-1). The intra and inter-assay precisions were all below 12.9%, the accuracies were all in standard ranges. Stability testing indicated that clevidipine butyrate and clevidipine acid in dog blood with the addition of denaturant methanol was stable under various processing and/or handling conditions. The validated method has been successfully applied to a pharmacokinetic study of clevidipine butyrate injection to 8 healthy Beagle dogs following intravenous infusion at a flow rate of 5 mg · h(-1) for 0.5 h.

Tissue distribution and excretion of bromotetrandrine in rats / 药学学报

<p><b>AIM</b>To study the tissue distribution and excretion of bromotetrandrine (W198) in rats.</p><p><b>METHODS</b>The concentrations of W198 in biological samples were determined by an HPLC method with UV detection.</p><p><b>RESULTS</b>After a single i.v. dose of 20 mg x kg(-1) W198 in rats, the parent drug concentrations in tissues were higher than those in blood at the same time. Parent drug was mainly distributed in lung, kidney, heart and liver, the peak levels were attained at 0.25 h and decreasing at 2 h after dosing in most tissues. After a single iv dose of 20 mg x kg(-1) W198 in rats, the excretion of the parent drug in urine, feces and bile amounted to 0. 150%, 2.1% and 0.063% of the dose, respectively.</p><p><b>CONCLUSION</b>W198 was mostly distributed in lung. The parent drug excretion was less than 3% via urine, feces and bile.</p>

Pharmacokinetics of bromotetrandrin (W198) in rats and beagle dogs / 药学学报

<p><b>AIM</b>To study the pharmacokinetics of bromotetrandrine (W198) in rats and beagle dogs.</p><p><b>METHODS</b>The concentrations of W198 in serum were determined using HPLC method with UV detection.</p><p><b>RESULTS</b>The pharmacokinetic parameters of W198 after single iv doses of W198 10, 20 and 40 mg x kg(-1) in rats were as follows: T1/2beta were 6.60, 7.36 and 6.77 h, AUC0-24 h were 3.797, 7.371 and 15.192 mg x h x L(-1), Vd were 7.14, 4.33 and 4.13 L x kg(-1), CL were 2.83, 2.60 and 2.71 L x (kg x h)(-1), respectively. The T1/2beta and AUCo-24 h of W198 after single im dose of W198 20 mg x kg(-1) in rats were 11.61 h and 12.646 mg x h x L(-1). The im bioavailability of W198 in rats was 56.9%. The T1/2beta, AUC0-24 h, Vd and CL of W198 after single iv dose of W198 5 mg x kg(-1) in beagle dogs were 11.72 h, 12.646 mg x h x L(-1), 0.70 L x kg(-1) and 0.46 L x (kg x h)(-1), respectively. The plasma protein binding ratio of W198 with human serum protein was 78.0%.</p><p><b>CONCLUSION</b>The absorption of W198 in rats was of first order kinetics.</p>

Bioavailability of ubiquinone 10 tablets in healthy volunteers / 中国临床药理学与治疗学

Aim To compare the bioavailability of two ubiquinone tablets in healthy volunteers. Methods A HPLC method was used to determine the serum ubiquinone 10 concentrations at 0,1,2,3,4,6,8 and 12 h after oral administration for 7 days ( 20 mg, tid ) in a cross-over test. Results AUC, Cmax and Tpeak of the test tablets were (5.91?1.78)?g?h?ml-1 ,(0.66?0.17)?g?ml-1 and (4.00?1.25) h, respectively,and these of the reference tablets were (6.30?2.09)?g?h?ml-1,(0.70?0.20)?g?ml-1 and (4.60?1.58)h , respectively . All of these parameters between the two kinds of tablets were not significantly different statistically. Conclusion The related bioavailability of the test tablets versus the reference tablets is 93.9%. The two formulations of ubiquinone 10 are bioequivalent.