title: Dose reduction of efavirenz: an observational study describing cost-effectiveness, pharmacokinetics and pharmacogenetics.
abstract: OBJECTIVE
  Antiretroviral treatment implies a high cost to the healthcare system. The aim of this study was to evaluate the clinical and economic impact of efavirenz (EFV) dose adjustment by monitoring plasma concentrations and pharmacogenetic analysis of the 516G>T CYP2B6 polymorphism.
  
  
  METHODS
  One hundred and ninety HIV patients treated with EFV were studied. Plasma EFV concentrations were measured by HPLC with ultraviolet detection, and pharmacogenetic analysis was performed by Real Time (RT)-PCR.
  
  
  RESULTS
  One hundred and ninety patients initially treated with a standard dose of EFV (600 mg/day) were studied. In 31 (16.3%) patients, EFV dose was reduced. A total of 87.1% of patients were heterozygous/homozygous carriers (GT/TT). CD4(+) count increased while the minimum steady-state plasma concentration and adverse effects decreased significantly after dose adjustment. Considering only the dose reduction, the adjustments accounted for a saving of 43,539 €/year.
  
  
  CONCLUSIONS
  The individualization of EFV dosage guided by genotyping 516G>T CYP2B6 and therapeutic drug monitoring could increase the efficiency of EFV use in antiretroviral treatment.
authors: Servicio de Farmacia, Hospital Univeristario de Salamanca, Spain.
authors: Almudena Sánchez
authors: AS
authors: Martín
authors: Alicia Iglesias
authors: AI
authors: Gómez
authors: Belén
authors: B
authors: García-Berrocal
authors: Salvador Cabrera
authors: SC
authors: Figueroa
authors: Miguel Cordero
authors: MC
authors: Sánchez
authors: María Victoria
authors: MV
authors: Calvo Hernández
authors: Jose Manuel
authors: JM
authors: Gonzalez-Buitrago
authors: María Paz
authors: MP
authors: Valverde Merino
authors: Carmen Bustos
authors: CB
authors: Tovar
authors: Aurelio Fuertes
authors: AF
authors: Martín
authors: María
authors: M
authors: Isidoro-García
mesh_terms: D000328:Adult; D000480:Alkynes; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D048588:Benzoxazines / Q000008:administration & dosage* / Q000493:pharmacokinetics; D003362:Cost-Benefit Analysis; D003521:Cyclopropanes; D065702:Cytochrome P-450 CYP2B6 / Q000235:genetics*; D016903:Drug Monitoring; D005260:Female; D005838:Genotype; D006678:HIV / Q000187:drug effects; D015658:HIV Infections / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010597:Pharmacogenetics
chemical_list: D000480:Alkynes; D019380:Anti-HIV Agents; D048588:Benzoxazines; D003521:Cyclopropanes; C585599:CYP2B6 protein, human; D065702:Cytochrome P-450 CYP2B6; C098320:efavirenz
keywords: CYP2B6; HIV; antiretroviral treatment; efavirenz; efficiency; pharmacogenetics; pharmacokinetics; therapeutic drug monitoring