Rapid and simultaneous determination of efavirenz, 8-hydroxyefavirenz, and 8,14-dihydroxyefavirenz using LC-MS-MS in human plasma and application to pharmacokinetics in healthy volunteers

Kwon Bok Kim, Hyunmi Kim, Fen Jiang, Chang Woo Yeo, Soo Kyung Bae, Zeruesenay Desta, Jae Gook Shin, Kwang Hyeon Liu

Research output: Contribution to journalArticle

5 Scopus citations


We developed a rapid and sensitive method for determining efavirenz, 8-hydroxyefavirenz, and 8,14-dihydroxyefavirenz in human plasma simultaneously using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Three compounds and ritonavir, an internal standard, were extracted from plasma using ethyl acetate in the presence of 0.1 M sodium carbonate after incubation of β-glucuronidase (500 U). After drying the organic layer, the residue was reconstituted in mobile phase (acetonitrile:20 mM ammonium acetate, 90:10, v/v) and injected onto a reversed-phase C18 column. The isocratic mobile phase was eluted at 0.2 mL min-1. The ion transitions monitored in multiple reaction-monitoring mode were m/z 314 → 244, 330 → 258, 346 → 262, and 721 → 296 for efavirenz, 8-hydroxyefavirenz, 8,14-dihydroxyefavirenz, and ritonavir, respectively. The retention time is 1.93, 1.70, 1.52, and 1.82 min for efavirenz, 8-hydroxyefavirenz, 8,14-dihydroxyefavirenz, and ritonavir, respectively. The coefficients of variation of the assay precision were less than 10.7%, and the accuracy was 90-111%. The lower limits of quantification (LLOQ) were 5 ng mL-1 for efavirenz and 8-hydroxyefavirenz. This method was used to measure the plasma concentrations of efavirenz and its metabolites from healthy volunteers after a single 600 mg oral dose of efavirenz. This analytical method is a very rapid, sensitive, and accurate to determine the pharmacokinetic profiles of efavirenz including its metabolites.

Original languageEnglish (US)
Pages (from-to)263-271
Number of pages9
Issue number3-4
StatePublished - Feb 1 2011



  • 8,14-Dihydroxyefavirenz
  • 8-Hydroxyefavirenz
  • Column liquid chromatography-tandem mass spectrometry
  • Efavirenz
  • Human plasma

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Clinical Biochemistry
  • Organic Chemistry

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