title: Variability in non-nucleoside reverse transcriptase and protease inhibitor concentrations among HIV-infected adults in routine clinical practice.
abstract: OBJECTIVE
  The objective of this study was to assess interindividual variability in trough concentrations of plasma of non-nucleoside reverse transcriptase inhibitors (NNRTI) and protease inhibitors (PI) among HIV-infected adults in a routine outpatient setting.
  
  
  METHODS
  One hundred and seventeen patients who attended our clinic for routine blood tests, and who were receiving antiretroviral therapy which included NNRTI or PI were studied. Patients were not informed that drug concentrations were going to be measured until blood sampling. The times of the last antiretroviral dose and of blood sampling were recorded. Drug concentrations were considered optimal if they were above the proposed minimum effective value. In addition, efavirenz, nevirapine and atazanavir concentrations were considered potentially toxic if they were > 4.0 mg l(-1), > 6.0 mg l(-1) and > 0.85 mg l(-1), respectively.
  
  
  RESULTS
  Overall, interindividual variability of NNRTI and PI concentrations in plasma was approximately 50%, and only 68.4% of the patients had drug concentrations within the proposed therapeutic range. Poor adherence explained only 35% of subtherapeutic drug concentrations.
  
  
  CONCLUSIONS
  Interindividual variability in trough concentrations of NNRTI and PI among HIV-infected adults is large in routine clinical practice, with drug concentrations being outside the therapeutic window in a significant proportion of patients. These findings provide further evidence that therapeutic drug monitoring may be useful to guide antiretroviral therapy in clinical practice.
authors.affiliation: Lluita Contra la SIDA Foundation, Badalona, Barcelona, Spain. jmolto@flsida.org
authors.forename: José
authors.initials: J
authors.lastname: Moltó
authors.forename: Asunción
authors.initials: A
authors.lastname: Blanco
authors.forename: Cristina
authors.initials: C
authors.lastname: Miranda
authors.forename: José
authors.initials: J
authors.lastname: Miranda
authors.forename: Jordi
authors.initials: J
authors.lastname: Puig
authors.forename: Marta
authors.initials: M
authors.lastname: Valle
authors.forename: Meritxell
authors.initials: M
authors.lastname: DelaVarga
authors.forename: Carmina R
authors.initials: CR
authors.lastname: Fumaz
authors.forename: Manuel José
authors.initials: MJ
authors.lastname: Barbanoj
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000097:blood* / Q000627:therapeutic use; D005260:Female; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D008297:Male; D011480:Protease Inhibitors / Q000097:blood* / Q000627:therapeutic use; D018894:Reverse Transcriptase Inhibitors / Q000097:blood* / Q000627:therapeutic use
chemical_list: D019380:Anti-HIV Agents; D011480:Protease Inhibitors; D018894:Reverse Transcriptase Inhibitors