Aim To develop a sensitive and specific LC/MS/MS
method for determination of lornoxi cam in human
plasma and investigate
pharmacokinetics of single dose of lornox icam in healthy Chinese volunteers. Methods
Lornoxicam and the internal
standard piroxicam were extracted from plasma using liquid-liquid extraction, then separated on a Zorbax XDB-C 8 column. The mobi le phase consisted of methanol-water-formic acid (80∶20∶0 5) at a flow-ra te of 0 7 mL·min -1 . A Finnigan TSQ tandem mass spectrometer equipped with atmospheric pressure chemical ionization source was used as detector and o perated in the positive ion mode. Selected reaction monitoring (SRM) using the p recursor → product ion combinations of m/z 372→121 and m/z 332 →121 was used to quantify lornoxicam and internal standard, respectively. Results The linear calibration curves were
obtained in the concentration range of 2 0- 1 600 μg·L -1 . The limit of quantitation was 2 0 μg·L -1 . The method was suc cessfully used in the pharmacokinetic study for lornoxicam. The main parameters obtained after an oral dose of 8 mg lornoxicam to 18 Chinese male volunteers wer e as follows: the value of T 1/2 was (4 7±1 1) h, AUC 0-∞ was found to be (5 5±2 4) mg·h·L -1 . However, T 1/2 of 105 h and AUC 0-∞ of 189 5 mg·h·L -1 were obtained for another volun teer. Conclusion The method is proved to be suitable for clinical investigation of lornoxicam pha rmacokinetics, which offers advantages of specificity, speed, and higher sensiti vity over the previously reported methods.
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