Effect of patient genetics on etonogestrel pharmacokinetics when combined with efavirenz or nevirapine ART

Megan Neary, Catherine A. Chappell, Kimberly K. Scarsi, Shadia Nakalema, Joshua Matovu, Sharon L. Achilles, Beatrice A. Chen, Marco Siccardi, Andrew Owen, Mohammed Lamorde

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background: We previously demonstrated that etonogestrel concentrations were 82% lower in women using etonogestrel contraceptive implants plus efavirenz-based ART compared with women not receiving ART. Objectives: To investigate the genetic contribution to this previously observed drug-drug interaction through studying SNPs in genes known to be involved in efavirenz, nevirapine or etonogestrel metabolism in the same group of women. Patients and methods: Here, we present a secondary analysis evaluating SNPs involved in efavirenz, nevirapine and etonogestrel metabolism and associated etonogestrel pharmacokinetics among 57 women, 19 not receiving ART (control group), 19 receiving efavirenz-(600 mg daily) based ART and 19 receiving nevirapine-(200 mg twice daily) based ART. Associations between patient genotype and etonogestrel pharmacokinetic parameters were determined through univariate and multivariate linear regression. This study was registered at clinicaltrials.gov (NCT02082652). Results: Within the control group, CYP2B6 983 T>C was associated with 27% higher etonogestrel Cmax and 28% higher AUC0-24weeks. In the efavirenz group CYP2B6 516 G>T was associated with 43% lower etonogestrel Cmin and 34% lower AUC0-24weeks. For participants receiving nevirapine, NR1I2 63396 C>T was associated with 39% lower etonogestrel Cmin and 37% lower AUC0-24weeks. Conclusions: This study demonstrates the influence of pharmacogenetics on the extent of drug-drug interactions between etonogestrel and efavirenz-or nevirapine-based ART. Efavirenz plus the etonogestrel contraceptive implant results in a detrimental drug-drug interaction irrespective of patient genetics, which is worsened in women possessing variant alleles for these CYP2B6 SNPs.

Original languageEnglish (US)
Pages (from-to)3003-3010
Number of pages8
JournalJournal of Antimicrobial Chemotherapy
Issue number10
StatePublished - Oct 1 2019

ASJC Scopus subject areas

  • Microbiology (medical)
  • Pharmacology (medical)
  • Infectious Diseases
  • Pharmacology


Dive into the research topics of 'Effect of patient genetics on etonogestrel pharmacokinetics when combined with efavirenz or nevirapine ART'. Together they form a unique fingerprint.

Cite this