Therapeutic drug monitoring of nelfinavir and indinavir in treatment-naive HIV-1-infected individuals. A randomized controlled trial of therapeutic drug monitoring in treatment-naive and -experienced HIV-1-infected patients. Therapeutic drug monitoring of nevirapine reduces pharmacokinetic variability but does not affect toxicity or virologic success in the ATHENA study. A randomized controlled trial to evaluate antiretroviral salvage therapy guided by rules-based or phenotype-driven HIV-1 genotypic drug-resistance interpretation with or without concentration-controlled intervention: the Resistance and Dosage Adapted Regimens (RADAR) study. Concentration-controlled compared with conventional antiretroviral therapy for HIV infection. PharmAdapt: a randomized prospective study to evaluate the benefit of therapeutic monitoring of protease inhibitors: 12 week results.
Both virological failure and the toxicity of HIV protease inhibitors have been related to interindividual variability of plasma drug concentrations. Therapeutic drug monitoring (TDM) offers the possibility to detect patients with drug concentrations outside therapeutic ranges, who can subsequently benefit from dose modifications.
                ATHENA was a randomized controlled clinical trial. Subjects were randomly assigned to either a TDM group, in which the results of drug concentration measurements plus advice were reported to their treating physician, or to a control group for whom TDM results were not reported. This analysis refers to treatment-naive patients who started a regimen containing indinavir or nelfinavir before November 1999.
                A total of 147 patients were randomly assigned: 92 to nelfinavir, 55 to indinavir. After one year of follow-up significantly fewer patients in the TDM group had discontinued nelfinavir or indinavir than in the control group: 17.4 versus 39.7%. This was mainly driven by a significantly lower rate of discontinuation because of virological failure in nelfinavir patients: 2.4% in the TDM group versus 17.6% in the control group, and by a non-significant difference in the rate of discontinuation because of toxicity in indinavir patients: 14.3% in the TDM group versus 29.6% in the control group. In a non-completer equals failure analysis of all randomized patients, the TDM group showed a significantly higher proportion of patients with a viral load below 500 copies after 12 months of treatment (78.2 versus 55.1%).
                TDM of nelfinavir and indinavir in treatment-naive patients improves treatment response. To improve the utility of therapeutic drug monitoring (TDM) by defining the proportion of patients with and predictors of above or below target protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor (NNRTI) concentrations.
                This 48-week, multicenter, open-label clinical trial randomized patients to TDM versus standard of care (SOC). Serial pharmacokinetics, including a week-2 3-sample sparse collection, and expert committee TDM recommendations were given to TDM-arm patients' providers.
                Seventy-four (39%) of 190 patients had week-2 concentrations outside of targets and 122 (64%) of 190 had nontarget exposure at least once over 48 weeks. Providers accepted 75% of TDM recommendations. Among patients with below-target concentrations, more TDM-arm than SOC-arm patients achieved targets (65% vs. 45%; P = 0.09). Increased body weight and efavirenz or lopinavir/ritonavir use were significant predictors of nontarget concentrations. Patients at target and patients who achieved targets after TDM-directed dose modifications trended toward greater viral load reductions at week 48 than patients with below-target exposures (HIV RNA reductions: 2.4, 2.3, and 1.9 log10 copies/mL, respectively; P = 0.09).
                Most patients had nontarget PI and/or NNRTI concentrations over 48 weeks. TDM recommendations were well accepted and improved exposure. Patients below TDM targets trended toward worse virologic response. nan It is not well defined whether concentration-controlled intervention (CCI) and rules-based human immunodeficiency virus (HIV) type 1 genotype drug-resistance interpretation (GI) or virtual phenotype drug-resistance interpretation (VPI) may improve the outcome of HIV salvage therapy.
                In a prospective, randomized, controlled trial, patients were randomized (on a factorial basis) to change treatment after either GI or VPI, and they then were further randomized to the control arm (no CCI) or the CCI arm. Protease inhibitor (PI) and nonnucleoside reverse-transcriptase inhibitor (NNRTI) trough concentration (Ctrough) values were determined at weeks 1, 4, 12, and 24 of the study.
                Among 230 patients, virological benefit (defined by an HIV RNA load of <400 copies/mL at week 24) was not statistically different, either between patients in the GI and VPI arms or between patients in the CCI and control arms. A virological benefit was found for patients in the CCI arm, compared with patients in the control arm, but this benefit was not statistically significant (56.8% vs. 64.3% at week 4 and 63.6% vs. 74% at week 12). Dosage adaptation was possible for only a fraction of patients, because of low rates of treatment adherence or patient refusal to increase dosages. In the logistic regression analysis, independent predictors of virological response at week 24 were a PI Ctrough value and/or an NNRTI Ctrough value in the higher quartiles (or above cutoff levels) and a low number of PIs previously received. Moreover, receipt of a regimen that contained PIs boosted with ritonavir was an independent predictor of virological response.
                The present study did not support the routine use of CCI for patients undergoing salvage treatment, probably as a result of existing difficulties associated with its clinical application. However, a higher Ctrough value appeared to be correlated with treatment response. No major differences were found between VPI or GI when they are used together with expert advice for the selection of salvage treatment combinations. To demonstrate the feasibility of a concentration-controlled approach to combination antiretroviral therapy, and to compare the virological responses and safety of this strategy versus conventional fixed-dose therapy.
                A prospective, randomized, 52 week, open-label trial of concentration-controlled compared with conventional dose zidovudine, lamivudine, and indinavir therapy conduced in a university-based general clinical research center in the United States.
                Forty antiretroviral-naive individuals with plasma HIV-RNA levels > 5000 copies/ml.
                Zidovudine, lamivudine, and indinavir plasma concentrations were measured in all participants. Doses were adjusted in those assigned to concentration-controlled therapy to achieve levels equal to or greater than target values.
                The proportion of patients who achieved the desired drug concentrations, the proportion of patients with HIV-RNA levels < 50 copies/ml at week 52, and safety and tolerance in the concentration-controlled versus conventional therapy arms.
                Significantly more concentration-controlled recipients achieved the desired concentration targets for all three drugs: 15 of 16 concentration-controlled recipients compared with nine of 17 conventional recipients (P = 0.017) had HIV-RNA levels < 50 copies/ml at week 52. No difference was observed in the occurrence of drug-related clinical events or laboratory abnormalities between the two treatment arms.
                Concentration-controlled therapy implemented simultaneously for three antiretroviral agents was feasible, as well tolerated as conventional therapy, and resulted in a greater proportion of recipients with HIV-RNA levels < 50 copies/ml after 52 weeks. These findings provide a scientific basis to challenge the accepted practice of administering the same dose of antiretroviral agents to all adults, ignoring the concentrations actually achieved. A randomized study to evaluate the usefulness of protease inhibitor (PI) therapeutic drug monitoring (TDM) in antiretroviral-experienced HIV-infected patients.
                In the control arm, treatment was modified according to genotypic resistance testing. In the TDM arm, therapy was modified on the basis of genotypic resistance testing and at week 8 according to PI plasma trough levels measured at week 4. The major endpoint was the change in HIV-RNA levels at week 12.
                A total of 183 patients, 96 in the control arm and 87 in the TDM arm, were included in the study. Low-dose ritonavir to enhance the associated PI was prescribed to 62.5% of patients in the control arm and 65.5% of patients in the TDM arm. Using our PI concentration targets, 17/81 patients (21%) in the TDM arm were considered to have suboptimal or partly optimal PI plasma levels at week 4. Physician and protocol-driven PI modifications were performed in 18/85 patients (23.5%) in the TDM arm, and in seven of 94 patients (7%) in the control arm (P < 0.01). Week 12 HIV RNA dropped 2 log10 copies/ml in the control arm and 1.7 log10 copies/ml in the TDM arm, respectively.
                We found no statistically significant difference between the TDM arm and control arm in virological outcome at week 12. The utility of TDM could be dependent on the presence of low-dose ritonavir as a booster and the antiretroviral experience of the studied population. Effective non-toxic target concentrations for resistant viruses have still to be determined.
                Copyright 2002 Lippincott Williams & Wilkins
Our review does not support routine use of ARV TDM in ARV-naive or -experienced patients on either boosted PI or NNRTI ART regimens. TDM in treatment-naive participants on a PI-based ART regimen, particularly if unboosted by ritonavir, may improve virological outcomes. Trials were underpowered with small sample sizes, short durations of follow-up and generally poor uptake of TDM recommendations. As these trials were conducted in higher income earning countries, results may not be generalisable to resource-limited countries where the burden of HIV is heaviest.