[Plasma ibuprofen enantiomers and their pharmacokinetics in Beagle dogs determined by HPLC].

A chiral high-performance liquid chromatography method was developed for the simultaneous determination of ibuprofen enantiomers in dog plasma. It was used to study the pharmacokinetics in the Beagle dog after intravenous administration of racemic-ibuprofen, S-ibuprofen and R-ibuprofen. Ketoprofen was chosen as the internal standard. After a simple precipitation using methanol as the precipitating solvent, both analytes and IS were separated on a Kromasil 100-5CHI-TBB chiral column (250 mm x4.6 mm, 5 µm) with isocratic elution using acetonitrile - 20 mmol x L(-1) phosphate buffer (pH 3.0, containing 5% methanol) (6 : 4) as the mobile phase. The detection wavelength was 220 nm. Liner calibration curves for both of the ibuprofen enantiomers were over the concentration range from 0.5 to 50 µg x mL(-1) with a lower limit of quantification of 0.5 µg x mL(-1), the accuracies were all in standard ranges. The intra- and inter- assay precisions were all below 7%. The recovery rate was 93.1% to 100.4%. The experiments proved that the method was simple, rapid and sensitive. It can be used in the quantitative determination of ibuprofen enantiomers in dog plasma. The method was used to determine the concentration of ibuprofen enantiomers in Beagle dog plasma after a single intravenous administration of racemic-ibuprofen, S-ibuprofen and R-ibuprofen (9 mg x kg(-1)) and the pharmacokinetics parameters were calculated based on the concentration-time curves. The C(max) of S-ibuprofen in Beagle dog plasma after a single intravenous administration of racemic-ibuprofen, S-ibuprofen and R-ibuprofen were 30.8 ± 4.7, 46.1 ± 5.9 and 20.0 ± 2.6 µg x mL(-1), respectively. In terms of the exposure of active ingredient, it revealed a significant difference between the administration of S-ibuprofen and the other two groups. The systematical R- to S- chiral inversion was discussed. Comparing the pharmacokinetic parameters at different doses, chiral inversion were 70.1% ± 36.6% and 76.4% ± 36.2%, respectively, after intravenous administration of racemic- and R-ibuprofen. This study provides a theoretical basis for the safety of ibuprofen formula of injection drug.

[Determination of decapeptide LXT-101 in plasma by HPLC-MS/MS and its pharmacokinetics in Beagle dogs].

This paper developed a sensitive and specific liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/MS) method for the determination of decapeptide LXT-101 in Beagle dog plasma. Plasma samples spiked with internal standard (IS) were treated with acetonitrile to precipitate the protein. Selected reaction monitoring (SRM) using the precursor --> product ion combinations of m/z 472.1-->587.9 and m/z 502.8-->633.8 were used to quantify LXT-101 and IS, respectively. The linear calibration curves were obtained in the concentration range of 0.5 - 500.0 ng x mL(-1). The limit of quantification (LOQ) was 0.5 ng x mL(-1). The inter-day and intra-day precision (RSD) across three validation run over the entire concentration range was below 10.9%, and the accuracy (RE) was within +/- 1.8%. The main pharmacokinetic parameters of LXT-101 after muscle injection of 20 microg x kg(-1) were as follows, AUC(0-t): (176.8 +/- 116.7) microg x h x L(-1), MRT(0-t): (2.52 +/- 0.53) h, T(1/2): (1.4 +/- 0.3) h; CL: (0.16 +/- 0.09) L x h(-1) x kg(-1), and Vd: (0.30 +/- 0.16) L x kg(-1), respectively. The method is proved to be specific, sensitive and suitable for the investigation of LXT-101 pharmacokinetics in Beagle dog.

[Determination of cinnabar in zijinhong capsules by high performance liquid chromatography].

A high performance liquid chromatographic method was established for the determination of cinnabar in Zijinhong capsules using diethyldithiocarbamate (DEDTC) chelate. A Waters X-Terra C18 column was used with a mixture of methanol-0.01 mol/L Na2HPO4 (pH 7.5) (containing 0.01% DEDTC) (73:27, V/V) as the mobile phase and a detector set at 270 nm. The calibration curve was linear (r = 0. 999 6) in the range of 10.1 mg/L - 100.9 mg/L of Hg2+. The recoveries were 97.0% - 100.8% with RSDs of 1.8% - 2.3%.