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Glucuronidation of Efavirenz and its Cytochrome P450‐dependent Metabolites in Brain Microsomes and Neurons
Author(s) -
Wheeler Abigail,
Bumpus Namandjé
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.03511
Subject(s) - efavirenz , glucuronidation , microsome , pharmacology , chemistry , metabolite , cytochrome p450 , reverse transcriptase inhibitor , biochemistry , biology , metabolism , human immunodeficiency virus (hiv) , enzyme , reverse transcriptase , virology , antiretroviral therapy , rna , viral load , gene
Efavirenz (EFV) is a non‐nucleoside reverse transcriptase inhibitor (NNRTI) anti‐HIV medication that is glucuronidated by UDP‐glucuronosyl transferases (UGTs). Brain penetrant anti‐HIV drugs, such as EFV, are essential to combatting HIV in the brain. Persons with HIV often suffer from neurocognitive deficits, known as HIV‐associated neurocognitive disorder (HAND). In addition to HAND, EFV itself has been shown to lead to severe neurological adverse events that can result the discontinuation of EFV‐based therapies. Despite the importance of this drug and the observed adverse side effects, its metabolism in the brain is virtually unknown. Furthermore, UGT expression and activity in the brain remains poorly understood. We tested whether EFV and/or its cytochrome P450‐dependent metabolites –8‐hydroxyefavirenz (8‐OHEFV) and 8,14‐dihydroxyefavirenz (8,14‐diOHEFV) undergo glucuronidation in the brain. To investigate this, brain microsomes and primary mouse neurons in culture were incubated with EFV, 8‐hydroxyefavirenz (8‐OHEFV), or 8,14‐dihydroxy efavirenz (8,14‐diOHEFV). Glucuronidated metabolites were detected using ultra‐high performance liquid chromatography tandem mass spectrometry (UHPLC MS/MS). Incubating pooled brain microsomes from mice, cynomolgus macaques, and humans with 10µM EFV or one of its cytochrome P450‐dependent metabolites for 30 min, we observed the formation of glucuronidated metabolites of 8‐OHEFV and 8,14‐diOHEFV for all three species. Interestingly, the cynomolgus macaque microsomes were the only microsomes to yield the EFV N‐glucuronide metabolite, indicating interspecies differences in UGT activity toward EFV. In primary C57BL6/J neurons treated with a drug concentration of 50µM for 3‐4 hours, we observed glucuronidation of 8‐OHEFV, but not EFV. This was commensurate with our findings using mouse brain microsomes. These data lend insight into EFV disposition in brain across humans, mice, and cynomolgus macaques, and can be leveraged to inform understanding of EFV‐mediated neurotoxicity.