title: Variability in the plasma concentration of efavirenz and nevirapine is associated with genotypic resistance after treatment interruption.
abstract: BACKGROUND
  Selection and persistence of non-nucleoside reverse transcriptase inhibitor (NNRTI)-associated mutations during treatment interruptions (TIs) has been attributed to the long plasma half-life of these drugs. However, little is known about the contribution of variable NNRTI plasma levels before a TI. We evaluated the selection of NNRTI-related mutations and the coefficient of variation of NNRTI plasma concentrations during different TI periods.
  
  
  METHODS
  The selection of NNRTI-related mutations was examined in 50 HIV type-1 (HIV-1)-infected patients on a virologically suppressive regimen who underwent TI guided by CD4+ T-cell counts and plasma viraemia. Population and clone-based sequencing of the reverse transcriptase coding region was performed using plasma HIV-1 RNA samples during TI and proviral DNA from peripheral blood mononuclear cells before TI. NNRTI plasma concentrations were determined by HPLC.
  
  
  RESULTS
  In 7/50 treated patients, de novo and transient NNRTI-related mutations appeared when treatment was interrupted. Emergence of resistant variants (including K103N, Y181C or G190S) after interruption was associated with a higher coefficient of variation in NNRTI plasma concentrations during the treatment period. Moreover, minority HIV-1 variants containing different resistance patterns (V1061/A, K103R/E or Y188C/D/H) were detected regardless of NNRTI concentrations.
  
  
  CONCLUSIONS
  The emergence of NNRTI-associated mutations during TI appears to be associated with the variation of NNRTI plasma concentrations during the preceding treatment period. The selection of minority HIV-1 variants with different patterns of NNRTI resistance in the absence of drug pressure should be considered for the efficacy of future NNRTI-containing antiretroviral regimens.
authors.affiliation: IrsiCaixa Foundation, Badalona, Spain. ldarwich@irsicaixa.es
authors.forename: Laila
authors.initials: L
authors.lastname: Darwich
authors.forename: Anna
authors.initials: A
authors.lastname: Esteve
authors.forename: Lidia
authors.initials: L
authors.lastname: Ruiz
authors.forename: Rocio
authors.initials: R
authors.lastname: Bellido
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
authors.forename: Javier
authors.initials: J
authors.lastname: Martinez-Picado
mesh_terms: D000480:Alkynes; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D048588:Benzoxazines / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D018791:CD4 Lymphocyte Count; D003521:Cyclopropanes; D004279:DNA, Viral / Q000097:blood; D004334:Drug Administration Schedule; D024882:Drug Resistance, Viral / Q000235:genetics*; D004359:Drug Therapy, Combination; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D009154:Mutation; D019829:Nevirapine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D011533:Proviruses / Q000302:isolation & purification; D012367:RNA, Viral / Q000097:blood; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use
chemical_list: D000480:Alkynes; D019380:Anti-HIV Agents; D048588:Benzoxazines; D003521:Cyclopropanes; D004279:DNA, Viral; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; D019829:Nevirapine; D054303:HIV Reverse Transcriptase; C098320:efavirenz