Separation and Determination of Diastereomeric Flurbiprofen Acyl Glucuronides in Human Urine by LC/ESI-MS with a Simple Column-Switching Technique

Nariyasu Mano, Takashi Narui, Ayako Nikaido, Junichi Goto

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Endogenous and exogenous compounds having a carboxyl group, such as a-arylpropionic acid derivatives, undergo a phase II metabolic reaction to produce an amino acid conjugate through the acyl CoA thioester as well as the acyl glucuronide. It was previously shown that flurbiprofen, one of the nonsteroidal anti-inflammatory drugs, is not subjected to activation of the carboxyl group by the CoA thioester ligase, suggesting that acyl glucuronidation is the main phase II metabolic pathway. Recent observations, however, have demonstrated that the nonenzymatic formation of a covalently protein-bound drug, which is produced by the action of the acyl glucuronide, may cause hypersensitive reactions. Accordingly, a reliable method to measure diastereomeric flurbiprofen glucuronides in human biological fluids is required. In this study, we describe a liquid chromatographic /mass spectrometric method with a simple column switching technique to determine diastereomeric flurbiprofen acyl glucuronides in human urine specimens. The optimal conditions for the electrospray ionization were established based on the effects of orifice and ring lens voltages as well as mobile phase additives. The proposed method applied to urine specimens demonstrates high accuracy and reproducibility for the determination of flurbiprofen glucuronides in a quantitative range from 0.74 to 146.5 mg /mL, with a detection limit of 7.4 pg (17.6 fmol)/injection of S-flurbiprofen glucuronide, at a signal-to-noise ratio of 10 under the selected ionmonitoring mode. The urinary concentration of R-flurbiprofen glucuronides in healthy subjects determined by the proposed method were 6.8-29.4 mg /mL, and those values were slightly higher than that of S-flurbiprofen glucuronides (3.9-18.0 mg /mL).

Original languageEnglish
Pages (from-to)142-149
Number of pages8
JournalDrug metabolism and pharmacokinetics
Issue number2
Publication statusPublished - 2002 Jan 1


  • LC /MS; column-switching
  • a-arylpropionic acid
  • acyl glucuronide
  • electrospray ionization
  • protein-bound adduct

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science
  • Pharmacology (medical)


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