Effect of therapeutic drug monitoring on outcome in antiretroviral experienced HIV-infected individuals

Background: The role of therapeutic drug monitoring (TDM) in the routine management of HIV-infected individuals is still unclear, largely due to a lack of basic data regarding specific drug concentrations and how they correlate with maximal effect and minimal toxicity within given populations. Nevertheless, it has a potentially important role to play in the management of HIV-infected patients, with the aim of limiting toxicity, optimising antiviral effect and decreasing virological failure and emergence of viral resistance. Objectives: To measure serum concentrations of specific antiretroviral drugs in individuals changing antiretroviral therapy and assess relationship to virological response. Study design: A prospective, non-randomised, 24-week study of 40 antiretroviral experienced HIV-infected patients. Subjects had failed their previous antiretroviral regimen and were beginning new regimens based on genotypic testing. Serum antiretroviral concentrations and virological response was measured after initiation of treatment. Results: There was a significant correlation between higher concentrations of lopinavir and efavirenz and better virological outcome. This was not seen with amprenavir. Conclusions: Use of TDM in this setting helps predict virological response to therapy. Optimal use of TDM would require dose adjustment on the basis of a TDM level. Further research is necessary to enable this practice to become routine in the management of HIV-infected patients. (C) 2002 Elsevier Science B.V. All rights reserved.