{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,26]],"date-time":"2025-10-26T14:27:21Z","timestamp":1761488841573,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2012,1,17]],"date-time":"2012-01-17T00:00:00Z","timestamp":1326758400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Efavirenz is a non-nucleoside reverse transcriptase inhibitor used for the treatment of human immunodeficiency virus type 1 infections. Drug interactions of efavirenz have been reported due to in vitro inhibition of CYP2C9, CYP2C19, CYP3A4, and UDP-glucuronosyltransferase 2B7 (UGT2B7) and in vivo CYP3A4 induction. The inhibitory potentials of efavirenz on the enzyme activities of four major UDP-glucuronosyltransferases (UGTs), 1A1, 1A4, 1A6, and 1A9, in human liver microsomes were investigated using liquid chromatography-tandem mass spectrometry. Efavirenz potently inhibited UGT1A4-mediated trifluoperazine N-glucuronidation and UGT1A9-mediated propofol glucuronidation, with Ki values of 2.0 and 9.4 \u03bcM, respectively. [I]\/Ki ratios of efavirenz for trifluoperazine N-glucuronidation and propofol glucuronidation were 6.5 and 1.37, respectively. Efavirenz also moderately inhibited UGT1A1-mediated 17\u03b2-estradiol 3-glucuronidation, with a Ki value of 40.3 \u03bcM, but did not inhibit UGT1A6-mediated 1-naphthol glucuronidation. Those in vitro results suggest that efavirenz should be examined for potential pharmacokinetic drug interactions in vivo due to strong inhibition of UGT1A4 and UGT1A9.<\/jats:p>","DOI":"10.3390\/molecules17010851","type":"journal-article","created":{"date-parts":[[2012,1,17]],"date-time":"2012-01-17T11:00:44Z","timestamp":1326798044000},"page":"851-860","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Effect of Efavirenz on UDP-Glucuronosyltransferase 1A1, 1A4, 1A6, and 1A9 Activities in Human Liver Microsomes"],"prefix":"10.3390","volume":"17","author":[{"given":"Hye Young","family":"Ji","sequence":"first","affiliation":[{"name":"National Research Laboratory of Drug Metabolism & Bioanalysis, College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyeri","family":"Lee","sequence":"additional","affiliation":[{"name":"National Research Laboratory of Drug Metabolism & Bioanalysis, College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea"},{"name":"Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sae Rom","family":"Lim","sequence":"additional","affiliation":[{"name":"National Research Laboratory of Drug Metabolism & Bioanalysis, College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeong Han","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1055-9628","authenticated-orcid":false,"given":"Hye Suk","family":"Lee","sequence":"additional","affiliation":[{"name":"National Research Laboratory of Drug Metabolism & Bioanalysis, College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2012,1,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1517\/17425250903483207","article-title":"Efavirenz in the therapy of HIV infection","volume":"6","author":"Rakhmanina","year":"2010","journal-title":"Expert Opin. 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