CYP2B6 genotype-directed dosing is required for optimal efavirenz exposure in children 3-36 months with HIV infection

Carolyn Bolton Moore*, Edmund V. Capparelli, Pearl Samson, Mutsa Bwakura-Dangarembizi, Patrick Jean-Philippe, Carol Worrell, Barbara Heckman, Lynette Purdue, Stephen A. Spector, Alex Benns, William Borkowsky, Amy Loftis, Elizabeth Hawkins, Carole Wallis, Ellen G. Chadwick

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Objectives: To determine safety-specific, efficacy-specific and genotypic-specific dose requirements of efavirenz (EFV) in children aged 3 to less than 36 months with HIV infection. Design: IMPAACT P1070 was a 24-week prospective cohort trial of EFV (as open capsules) and two nucleoside reverse transcriptase inhibitors in children with HIV infection 3 to less than 36 months without tuberculosis (Cohort 1). Methods: CYP2B6 G516T genotype was determined, and intensive pharmacokinetics was performed at week 2. EFV dose was adjusted if outside the target area under the curve (AUC) 35-180 (μLgh/ml. Pharmacokinetic and CYP2B6 G516T genotype data were used to model EFV exposures based on Food and Drug Administration (FDA)-approved doses. Results: Forty-seven participants, median age 19 months, initiated the study regimen with 24 weeks median follow-up; 38 516GG/GT and 9 516TT genotypes. Initially, median EFV AUC was higher in 516TTvs. 516GG/GT (median 490 vs. 107(μgh/ml; P= 0.0001) with all 516TT above AUC target. Following an amendment that reduced the 516TT EFV dose by 75%, pharmacokinetic modeling predicted that 83% of participants met the AUC target (31/38 516GG/GT, 8/9 516TT). In contrast, modeling using P1070 data predicted that FDA-approved doses would produce subtherapeutic AUCs in almost one-third of participants with 516GG/GT and excessive AUCs in more than 50% with 516TT genotypes. Conclusion: CYP2B6 G516T genotype strongly influences EFV exposures in this age group. Genotype-directed dosing yields therapeutic EFV concentrations and appears to outperform other dosing approaches.

Original languageEnglish (US)
Pages (from-to)1129-1136
Number of pages8
Issue number8
StatePublished - May 15 2017


  • CYP2B6 G516T genotype
  • Children
  • Efavirenz
  • HIV
  • Pharmacokinetics
  • Treatment

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Infectious Diseases


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