title: Influence of CYP2B6 polymorphisms on the persistence of plasma nevirapine concentrations following a single intra-partum dose for the prevention of mother to child transmission in HIV-infected Thai women.
abstract: OBJECTIVE
  To investigate the association of single nucleotide polymorphisms (SNPs) with nevirapine concentrations following intra-partum single-dose nevirapine.
  
  
  METHODS
  Plasma and DNA samples were obtained from 330 HIV-infected Thai women who received intra-partum single-dose nevirapine in the PHPT-2 clinical trial to prevent perinatal HIV transmission. Nine SNPs within CYP2B6, CYP3A4 and ABCB1 were genotyped by real-time PCR. Nevirapine plasma concentrations were determined by HPLC and used in a population pharmacokinetic analysis.
  
  
  RESULTS
  Higher nevirapine exposure was observed in women carrying the CYP2B6 516G>T polymorphism, but this did not reach statistical significance (P = 0.054). The TGATC CYP2B6 haplotype (g.3003T, 516G, 785A, g.18492T and g.21563C) was associated with increased nevirapine clearance and lower exposure (P = 0.0029). The median time for nevirapine concentrations to reach 10 ng/mL post-partum (nevirapine IC(50) for HIV-1) was 14 days [interquartile range (IQR, 14-18)] for TGATC homozygotes, 16 days (14-20) for TGATC heterozygotes and 18 days (14-20) for non-TGATC homozygotes (P = 0.020).
  
  
  CONCLUSIONS
  The CYP2B6 516G>T impact on nevirapine concentrations was less pronounced after intra-partum single-dose nevirapine than reported under steady-state conditions, perhaps due to lack of enzyme auto-induction at the time of dosing. Although the TGATC CYP2B6 haplotype may shorten the persistence of nevirapine post-partum, its practical implications for the prevention of HIV transmission or selection of resistance mutations are likely limited.
authors.affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Soranun
authors.initials: S
authors.lastname: Chantarangsu
authors.forename: Tim R
authors.initials: TR
authors.lastname: Cressey
authors.forename: Surakameth
authors.initials: S
authors.lastname: Mahasirimongkol
authors.forename: Edmund
authors.initials: E
authors.lastname: Capparelli
authors.forename: Yardpiroon
authors.initials: Y
authors.lastname: Tawon
authors.forename: Nicole
authors.initials: N
authors.lastname: Ngo-Giang-Huong
authors.forename: Gonzague
authors.initials: G
authors.lastname: Jourdain
authors.forename: Marc
authors.initials: M
authors.lastname: Lallemant
authors.forename: Wasun
authors.initials: W
authors.lastname: Chantratita
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D065702:Cytochrome P-450 CYP2B6; D005260:Female; D015658:HIV Infections / Q000517:prevention & control* / Q000635:transmission; D006239:Haplotypes; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control*; D019829:Nevirapine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D010089:Oxidoreductases, N-Demethylating / Q000235:genetics*; D010949:Plasma / Q000737:chemistry*; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D013785:Thailand; D013997:Time Factors; D055815:Young Adult
chemical_list: D019380:Anti-HIV Agents; D019829:Nevirapine; D001189:Aryl Hydrocarbon Hydroxylases; C585599:CYP2B6 protein, human; D065702:Cytochrome P-450 CYP2B6; D010089:Oxidoreductases, N-Demethylating