Homozygous CYP2B6 *6 (Q172H and K262R) correlates with high plasma efavirenz concentrations in HIV-1 patients treated with standard efavirenz-containing regimens

Biochem Biophys Res Commun. 2004 Jul 9;319(4):1322-6. doi: 10.1016/j.bbrc.2004.05.116.


Efavirenz (EFV) is metabolized by cytochrome P450 2B6 (CYP2B6) in the liver. We analyzed the genotypes of CYP2B6 and their contribution to plasma EFV concentrations in 35 EFV-treated patients in International Medical Center of Japan. The mean plasma EFV concentration of patients with CYP2B6 *6/*6 (Q172H and K262R) (25.4+/-7.5 microM, +/-SD, n = 2) was significantly higher than that of patients with genotypes *6 heterozygote (9.9+/-3.3 microM, n = 10) or without alleles *6 (8.0+/-2.6 microM, n = 23) (p < 0.0001). To confirm our result, we further analyzed nine patients (three with high EFV concentrations and arbitrarily selected six with normal EFV concentrations) treated in Osaka National Hospital, and it resulted that the only three patients with the high concentrations were the *6/*6 holder. EFV dose could be decreased in those patients harboring the genotype to reduce toxicity with compromising potency, representing the first step of the Tailor-Made therapy of HIV-1 infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkynes
  • Anti-HIV Agents / blood*
  • Aryl Hydrocarbon Hydroxylases / genetics*
  • Benzoxazines
  • Cyclopropanes
  • Cytochrome P-450 CYP2B6
  • Gene Frequency
  • Genotype
  • HIV Infections* / blood
  • HIV Infections* / drug therapy
  • HIV Infections* / genetics
  • HIV-1*
  • Oxazines / blood*
  • Oxidoreductases, N-Demethylating / genetics*
  • Polymorphism, Genetic*
  • Reverse Transcriptase Inhibitors / blood
  • Statistics as Topic


  • Alkynes
  • Anti-HIV Agents
  • Benzoxazines
  • Cyclopropanes
  • Oxazines
  • Reverse Transcriptase Inhibitors
  • Aryl Hydrocarbon Hydroxylases
  • Cytochrome P-450 CYP2B6
  • Oxidoreductases, N-Demethylating
  • efavirenz