Determination of nelfinavir, a potent HIV protease inhibitor, and its active metabolite M8 in human plasma by high-performance liquid chromatography with photodiode-array detection

Simple, Rapid and Validated LC Determination of Lopinavir in Rat Plasma and its Application in Pharmacokinetic Studies

Lopinavir is a new specific and potent HIV-1 protease inhibitor. A simple and rapid Reverse Phase High-Performance Liquid Chromatographic method using UV detection was developed and validated for the analysis of lopinavir in rat plasma under isocratic conditions. The method involves a single step protein precipitation technique. The detector response was linear over the concentration range of 250 to 4000 ng mL ⁻¹. High recovery ranging from 97.5 to 101.2 percent was obtained which precludes the use of internal standard. The developed method was validated as per standard guidelines. Validation of the developed method demonstrated accuracy, precision and selectivity of the proposed method. The drug was found to be stable under various processing and storage conditions. This rapid and cost-effective method was successfully applied in the estimation of lopinavir and determination of various pharmacokinetic parameters during post intravenous bolus administration of the drug in rats. The developed method can be suitably employed in preclinical pharmacokinetic evaluation of new formulations designed to improve the bioavailability of lopinavir.

Age-related changes in plasma concentrations of the HIV protease inhibitor lopinavir

The advent of highly active antiretroviral therapy in the treatment of HIV disease has substantially extended the lifespan of individuals infected with HIV resulting in a growing population of older HIV-infected individuals. The efficacy and safety of antiretroviral agents in the population are important concerns. There have been relatively few studies assessing antiretroviral pharmacokinetics in older patients. Thirty-seven subjects aged 18-30 years and 40 subjects aged 45-79 years, naive to antiretroviral therapy, received lopinavir/ritonavir (400/100) bid, emtricitibine 200 mg qd, and stavudine 40 mg bid. Trough lopinavir concentrations were available for 44 subjects, collected at 24, 36, and 96 weeks. At week 24, older age was associated with higher lopinavir trough concentrations, and a trend was observed toward older age being associated with higher lopinavir trough concentrations when all time points were evaluated. In the young cohort, among subjects with two or more measurements, there was a trend toward increasing intrasubject trough lopinavir concentrations over time. Using a nonlinear, mixed-effects population pharmacokinetic model, age was negatively associated with lopinavir clearance after adjusting for adherence. Adherence was assessed by patient self-reports; older patients missed fewer doses than younger patients (p = 0.02). No difference in grade 3-4 toxicities was observed between the two age group. Older patients have higher trough lopinavir concentrations and likely decreased lopinavir clearance. Age-related changes in the pharmacokinetics of antiretroviral drugs may be of increasing importance as the HIV-infected population ages and as older individuals comprise an increasing proportion of new diagnoses.

Treatment intensification does not reduce residual HIV-1 viremia in patients on highly active antiretroviral therapy

In HIV-1-infected individuals on currently recommended antiretroviral therapy (ART), viremia is reduced to <50 copies of HIV-1 RNA per milliliter, but low-level residual viremia appears to persist over the lifetimes of most infected individuals. There is controversy over whether the residual viremia results from ongoing cycles of viral replication. To address this question, we conducted 2 prospective studies to assess the effect of ART intensification with an additional potent drug on residual viremia in 9 HIV-1-infected individuals on successful ART. By using an HIV-1 RNA assay with single-copy sensitivity, we found that levels of viremia were not reduced by ART intensification with any of 3 different antiretroviral drugs (efavirenz, lopinavir/ritonavir, or atazanavir/ritonavir). The lack of response was not associated with the presence of drug-resistant virus or suboptimal drug concentrations. Our results suggest that residual viremia is not the product of ongoing, complete cycles of viral replication, but rather of virus output from stable reservoirs of infection.

Pharmacokinetic properties and tolerability of bevirimat and atazanavir in healthy volunteers: an open-label, parallel-group study

BACKGROUND

Bevirimat, an inhibitor of HIV-1 maturation, is currently in clinical development for the treatment of HIV-1 infection. It undergoes glucuronidation via uridine diphosphate glucuronosyltransferases (UGTs). The protease inhibitor atazanavir is a potent inhibitor of UGT1A1. Because of this inhibition, high atazanavir plasma levels are associated with increases in plasma bilirubin.

OBJECTIVES

The purposes of this study were to assess the pharmacokinetic (PK) properties and tolerability profiles of bevirimat administered as monotherapy and in combination with atazanavir.

METHODS

This was an open-label, parallel-group study in healthy volunteers. Nonsmoking men and women aged 18 to 60 years were eligible for inclusion in the study. After being stratified in a 1:1 ratio by sex, subjects were randomly assigned to 1 of 2 groups to receive bevirimat 200 mg/d for 14 days or atazanavir 400 mg/d on days 1 through 21 and bevirimat 200 mg/d on days 8 through 21. Bevirimat PK properties were assessed on day 14 in the monotherapy group and on day 21 in the combination group. Atazanivir PK properties were assessed on days 7 and 21 in the combination group. Serum bilirubin was assessed daily. Tolerability was assessed by monitoring of adverse events using physical examination and clinical laboratory evaluation, including recording of vital signs and electrocardiography throughout the study.

RESULTS

A total of 48 healthy volunteers (24 men, 24 women; mean age, 33 years; mean weight, 83.6 kg; mean body mass index, 27.8 kg/m(2)) were included in the study. There were no significant between-group effects on the PK properties with respect to geometric least squares mean ratios of C(max) and AUC(0-tau) (95.9 [90% CI, 84.5-108.8] and 92.0 [90% CI, 80.5- 105.2], bevirimat monotherapy vs bevirimat + atazanivir, respectively; and 93.9 [90% CI, 82.3-107.1 and 94.1 [90% CI, 78.2-113.1], atazanivir monotherapy vs bevirimat + atazanivir, respectively). Bevirimat was not associated with any significant changes from baseline in serum bilirubin concentrations, whereas 7-day atazanavir monotherapy was associated with a appromixately 5-fold increase. Coadministration was not associated with significant bilirubin concentration elevations compared with the administration of atazanavir alone. Dosing was discontinued in 4 subjects (atazanavir-induced hyperbilirubinemia, 3; atazanavir-induced rash, 1). In addition, 17 subjects (35.4%) experienced treatment-emergent adverse events including: ocular icterus, 5; headache, 5; unconjugated blood bilirubin increases, 4; diarrhea, 3; upper respiratory tract infection, 3; and yellow skin, 3.

CONCLUSIONS

In this study, there were no significant differences in PK properties in atazanavir or bevirimat administered as monotherapy or in combination in this small, select group of healthy volunteers. The coadministration of bevirimat and atazanavir was reasonably well tolerated. Bevirimat did not significantly increase serum bilirubin concentrations and had no significant effect on atazanavir-induced hyperbilirubinemia, potentially providing a further option in the management of HIV-1 infection following evaluation in HIV-infected patients.

Beneficial Pharmacokinetic Interaction Between Atazanavir and Lopinavir/Ritonavir

BACKGROUND

The combination of lopinavir/ritonavir (LPV/r) and atazanavir (ATV) with nucleoside reverse transcriptase inhibitors has been used as a salvage regimen in HIV-infected patients. Because these agents, to various degrees, are substrates, inducers, and inhibitors of CYP450 3A4, there is concern for alterations in the pharmacokinetics (PK) of these combined agents.

OBJECTIVE

To determine the steady-state PK interactions between ATV, ritonavir (RTV), and LPV when coadministered at various doses.

METHODS

HIV-negative subjects (n = 15) received a combination of ATV, RTV, and LPV in the following sequence: period I (days 1-10), ATV/r at a dose of 300/100 mg once daily; period II (days 11-24), ATV at a dose of 300 mg once daily plus LPV/r at a dose of 400/100 mg twice daily; and period III (days 25-34), ATV/r at a dose of 300/100 mg once daily plus LPV/r at a dose of 400/100 mg twice daily. Intensive PK analysis was performed on days 10, 24, and 34. A paired t test was used for pairwise comparison of log-transformed PK parameters of ATV and LPV.

RESULTS

In period II, the ATV minimum concentration (Cmin) geometric mean (GM) was higher compared with period I (GM: 0.75 vs. 0.51 microg/mL, geometric mean ratio (GMR) = 1.45, 90% confidence interval [CI]: 1.19 to 1.77; P = 0.006). The ATV area under the concentration-time curve from dosing to 24 hours after the dose (AUC0-24; GM: 36.40 vs. 39.62 microg.h/mL, GMR = 0.92, 90% CI: 0.80 to 1.05; P = 0.28) did not differ, however. The addition of 100 mg of RTV in period III did not significantly increase the ATV Cmin (GM: 0.84 vs. 0.75 microg/mL, GMR = 1.13, 90% CI: 0.91 to 1.40; P = 0.34) or ATV AUC0-24 (GM: 39.59 vs. 36.40 microg.h/mL, GMR = 1.09, 90% CI: 0.99 to 1.20; P = 0.14) compared with period II. The additional RTV in period III resulted in a higher LPV Cmin (GM: 5.12 vs. 3.99 microg/mL, GMR = 1.28, 90% CI: 1.15 to 1.43; P = 0.001), but the LPV areas under the concentration-time curve from dosing to 12 hours after the dose and maximum concentration were not significantly different. LPV PK parameters in period II were comparable to those of historical control subjects receiving LPV/r at a dose of 400/100 mg twice daily. All studied regimens were well tolerated. Indirect hyperbilirubinemia was the only grade 3 and 4 abnormality reported, which was expected given that ATV competitively inhibits UGTIA1 and has not been shown to result in other hepatic abnormalities.

CONCLUSIONS

The combination of ATV at a dose of 300 mg once daily plus LPV/r at a dose of 400/100 mg twice daily resulted in an appropriate PK profile for ATV and LPV and could be further evaluated in treatment-experienced patients requiring a dual-boosted protease inhibitor-containing regimen.

Psychological distress and physical pain appear to have no short-term adverse impact on plasma HIV-1 RNA levels in patients on successful HAART

PURPOSE

Previous studies have linked depression and stressful life events in HIV disease with a more rapid decline in CD4 count and progression to AIDS. However, the short-term effect of psychological and physical distress on HIV-1 RNA levels in patients on successful HAART has not been well studied.

METHOD

Ten asymptomatic HIV-infected adults with suppression of viremia to <50 copies/mL on a stable HAART regimen for > or =6 months were studied. Participants donated blood every 2-3 days over a 3-4 month period for duplicate independent viral load measurements and drug level monitoring. At each time point, psychological distress was measured using the Mental Health Inventory-5 (MHI-5) and an 11-point numeric rating scale for emotional stress. Physical pain was assessed using an 11-point numeric rating scale.

RESULTS

All patients maintained successful viral suppression throughout the study. Twenty-six of 713 (3.6%) viral load measurements were >50 copies/mL. Psychological distress and physical pain were not associated with episodes of detectable viremia.

CONCLUSION

Using frequent monitoring of HIV-1 RNA levels and patient ratings of mood, stress, and pain, we found that psychological distress and physical pain had no short-term adverse impact on HIV-1 RNA levels in highly adherent patients with stable suppression of viremia on HAART.

High variability of indinavir and nelfinavir pharmacokinetics in HIV-infected patients with a sustained virological response on highly active antiretroviral therapy

OBJECTIVES

To describe plasma concentrations of indinavir alone or combined with ritonavir, and of nelfinavir and its active metabolite M8, and to measure their variabilities in HIV-infected patients treated with a stable antiretroviral regimen and experiencing a sustained virological response for at least 12 months.

PATIENTS AND METHODS

In this prospective trial, blood samples were drawn during a 6-hour time interval between two doses at enrolment to assess protease inhibitor (PI) pharmacokinetic parameters, and 4 months later to assess plasma trough and peak concentrations. Safety and adherence assessments and laboratory data were collected during an 8-month period. PI pharmacokinetic characteristics were analysed using a non-compartmental approach. Inter- and intrapatient variabilities were estimated using a linear mixed-effect model. The impact of different covariates on plasma trough concentrations was investigated. Eighty-eight patients were analysed: 42 treated with indinavir and 46 with nelfinavir.

RESULTS

The interquartile range (IQR) of the plasma trough concentration corrected for the sampling time (Ccalc) was 116-374 microg/L for indinavir alone and 163-508 microg/L for indinavir/ritonavir. Ritonavir significantly increased indinavir elimination half-life and plasma exposure. For nelfinavir, the IQR of Ccalc was 896-2059 microg/L for three-times-daily administration and 998-2124 microg/L for twice-daily administration. Variabilities were high for both PIs. Intrapatient variability for indinavir alone (and indinavir + ritonavir) was 76% (107%) and interpatient variability was 58% (10%) in adherent patients. Intrapatient variability for nelfinavir three times daily (and twice daily) was 41% (74%) and interpatient variability was 62% (50%). Intrapatient variability was lowered in patients with a high adherence level.

CONCLUSION

Although performed in a homogeneous population, this study documented a high interpatient but also intrapatient variability of indinavir and nelfinavir pharmacokinetics, which should be taken into account when interpreting therapeutic drug monitoring. Once patients have reached a sustained virological response, plasma PI monitoring may have a limited impact.

Placental transfer of lopinavir/ritonavir in the ex vivo human cotyledon perfusion model

OBJECTIVE

This study was done to determine the placental transfer of the human immunodeficiency virus protease inhibitor lopinavir with ritonavir.

STUDY DESIGN

Twenty-five human cotyledons that were obtained after uneventful pregnancies and deliveries were perfused in an open double circuit with lopinavir (1099-10,606 microg/L) and ritonavir (254-1147 microg/L) at various albumin concentrations (2, 10, and 40 g/L).

RESULTS

The fetal transfer rate of lopinavir, when combined with ritonavir, was 23.6% +/- 6.9% at an albumin concentration of 2 g/L. The fetal transfer rate decreased to 20.7% +/- 10% at an albumin concentration of 10 g/L and to 3.3% +/- 0.5% at an albumin concentration of 40 g/L.

CONCLUSION

The placental transfer of lopinavir, a highly protein-bound molecule, was compatible with passive diffusion of the unbound fraction. Even at physiologic maternal albumin concentrations, the amount of drug transferred into the fetal compartment was well above the 50% inhibitory concentration.

Marked Intraindividual Variability in Antiretroviral Concentrations May Limit the Utility of Therapeutic Drug Monitoring

BACKGROUND

Effective therapeutic drug monitoring for antiretrovirals requires a better understanding of intraindividual variability in pharmacokinetics.

METHODS

We determined concentrations of human immunodeficiency virus (HIV) protease and nonnucleoside reverse-transcriptase inhibitors for 10 patients with undetectable plasma HIV RNA levels who had been receiving stable regimens for > or = 11 months. Plasma samples were collected at the same time of day 3 times per week for up to 4 months. Patients were instructed to take their antiretrovirals at the same time every day. Plasma protease and nonnucleoside reverse-transcriptase inhibitor concentrations were determined using high-performance liquid chromatographic methods. Pharmacokinetic variability was expressed as intraindividual percentage coefficient of variation (ICV), which was calculated as the patient's standard deviation divided by the mean drug concentration for that patient.

RESULTS

ICV was determined for 6 drugs for 10 patients, for a total of 17 different patient-drug combinations, using 600 total samples. ICV was unexpectedly high for most patients who were receiving protease inhibitors (ICVs for individual patients taking lopinavir/ritonavir were 24%, 33%, 51%, and 92%; for patients taking nelfinavir/M8 metabolite, they were 30%/44% and 39%/54%; for patients taking ritonavir, they were 34% and 43%; for patients taking saquinavir, they were 52% and 55%). ICVs for patients receiving nonnucleoside reverse-transcriptase inhibitors were lower (for patients receiving efavirenz, they were 7%, 13%, 29%, and 51%; for a patient receiving nevirapine, it was 25%). The median ICV for all patients receiving protease inhibitors (n = 12) was 43.5%, and for all patients receiving nonnucleoside reverse-transcriptase inhibitors (n = 5), the median ICV was 25%.

CONCLUSIONS

Intraindividual variability in concentrations of antiretrovirals was surprisingly high in virologically suppressed patients. Possible contributors include food effects, concomitant use of prescription and herbal medications, assay variability, or medication timing, which was assessed by self-report. High intraindividual pharmacokinetic variability may limit the utility of single measurements in therapeutic drug monitoring for some antiretroviral agents.

Clinical validation of atazanavir/ritonavir genotypic resistance score in protease inhibitor-experienced patients

OBJECTIVE

To develop a clinically relevant genotypic resistance score for boosted atazanavir (ATV) in protease inhibitor-experienced patients.

METHODS

At baseline, 62 patients with HIV-1 RNA > 1000 copies/ml switched to a boosted ATV regimen (300 mg ATV, 100 mg ritonavir once daily); two were excluded from analysis at 3 months as they had undetectable plasma ATV. The impact of baseline protease mutations on virological response (> 1 log10 copies/ml plasma HIV RNA decrease) at 3 months was analysed using Fisher's exact test. Mutations with prevalence > 8% and P < 0.2 were retained. Cochran-Armitage's test was used to select the combination of mutations most strongly associated with reduced virological response. Robustness of the score was investigated using bootstrap resampling.

RESULTS

At 3 months, 82% of patients had a virological response and 56% had RNA < 50 copies/ml. Eight mutations (10F/I/V, 16E, 33I/F/V, 46I/L, 60E, 84V, 85V and 90M) were retained in the genotypic resistance score (P = 8.67 x 10) and virological response was observed in 100%, 100%, 80%, 42%, and 0% of patients with none, one, two, three, and four/five mutations, respectively. There was 100% response in patients with a score < 2 independently of the number of active drugs, whereas in patients with a score > or = 3 there was a gradient of response according to the number of active drugs (0%, 29% and 60% with none, one and two/three active drugs, respectively).

CONCLUSIONS

The occurrence of three of the eight mutations in the ATV/RTV genotypic resistance score predicted a clinically identifiable reduced response in patients.

Population pharmacokinetic analysis for nelfinavir and its metabolite M8 in virologically controlled HIV-infected patients on HAART

AIMS

To describe the pharmacokinetics of nelfinavir and its main metabolite M8 in HIV-infected patients with a sustained virological response, to characterize the effect of covariates and to estimate inter- and intra-individual variability in the pharmacokinetics.

METHODS

Three hundred and twenty concentrations of both nelfinavir and M8 were measured in 46 patients enrolled in the COPHAR 1-ANRS 102 study. Blood samples were taken at a first visit (one sample before drug administration and four samples at fixed times after) and at a second visit 1 to 3 months later (one before and one 3 h after drug administration). The data from both visits on nelfinavir and M8 were modelled jointly in all patients using a population approach.

RESULTS

A one-compartment model with first-order absorption and elimination best described nelfinavir data, with an additional compartment incorporating a first order rate-constant describing the metabolism of the drug to M8. For nelfinavir, the apparent volume of distribution (V/F ) (95% confidence interval for the mean), was 309 l (185, 516), the absorption rate constant (k(a)) was 0.4 h(-1) (0.2, 0.8), and the apparent clearance (CL/F ) was 37.3 l h(-1) (32, 44). For M8, V(m) /(Fk(m)) and CL(m)/(Fk(m)) were 866 l h(-1) (351, 2161) and 1670 l (965, 2894), respectively. The interindividual variabilities were 34.9%, 34.3% and 62.2% for V/F, CL/F and CL(m)/(Fk(m)), respectively. The interoccasion variability was 27.8% for CL/F. The mean half-lives were 05.38 h and 00.44 h for nelfinavir and M8, respectively. Significant but opposite effects of comedication with zidovudine were found on nelfinavir CL/F and M8 CL(m)/(Fk(m)), but they were not considered to be clinically relevant.

CONCLUSIONS

A joint model was found to describe adequately nelfinavir and M8 concentrations and was used to estimate pharmacokinetic parameters for M8. The model can be used to build reference pharmacokinetic profiles for therapeutic drug monitoring of the drug.

Genotypic resistance analyses in nucleoside-pretreated patients failing an indinavir containing regimen: results from a randomized comparative trial: (Novavir ANRS 073)

BACKGROUND

Different studies have shown that most patients failing a first-line treatment containing a protease-inhibitor (PI) had low PI plasma levels and no PI-related resistance mutations. NOVAVIR was a randomized trial comparing stavudine/lamivudine/indinavir (d4T/3TC/IDV) and zidovudine/lamivudine/indinavir (AZT/3TC/IDV) in patients pretreated with AZT, didanosine (ddI) and/or zalcitabine (ddC) but naive for PIs.

OBJECTIVE

To study the mechanisms of virological failure in NOVAVIR trial through analyses of genotypic resistance profiles of reverse transcriptase (RT) and protease (PR), and plasma IDV concentrations at time to failure.

METHODS

Plasma HIV-RNA PR and RT sequences were determined in 27 failing patients (d4T/3TC/IDV n=11; AZT/3TC/IDV n=16) at baseline and at time to failure. IDV plasma measurements were performed in both samples.

RESULTS

At baseline, 20 out of the 27 patients had at least two thymidine analogs associated mutations. At time to failure, mutation M184V in the RT gene was present in 22 out of the 27 failing patients. Thirteen out of the 27 (48%) patients had acquisition of PI mutations compared to baseline sequence. Of the 26 patients with adherence data, 13 (50%) subjects were classified as having difficulty in adherence. The proportion of patients with low adherence was higher in the subgroup of patients failing without acquisition of new PI mutations.

CONCLUSIONS

In patients experienced with NRTIs, failure to PI-containing regimen may occur in spite of appropriate adherence to therapy and is associated with emergence of PI mutations in half of the cases. These results suggest that, although PIs have a high genetic barrier, sub-optimal activity of associated drugs may favor the selection of PI resistance mutations.

Determination of indinavir and nelfinavir trough plasma concentration efficacy thresholds according to virological response in HIV-infected patients

BACKGROUND

There is evidence to suggest a pharmacokinetic-pharmacodynamic relationship in HIV-infected patients receiving protease inhibitor (PI)-containing highly active antiretroviral therapy (HAART); however, the effective trough PI plasma concentrations achieved have not been precisely determined.

METHODS

The relationship between HIV viral load and concomitant PI trough plasma concentration (C(trough)) was evaluated in 101 patients receiving at least 4 months of thrice daily indinavir (IDV)-containing (n=68) or nelfinavir (NFV)-containing (n=33) HAART. The more discriminating C(trough) efficacy thresholds were determined statistically for each PI by using the raw C(trough) and the time-corrected C(trough), using the precise delay since the last PI intake and the half-life of each PI.

RESULTS

For IDV (P=0.002) and NFV (P=0.019) median C(trough) levels were higher in patients with undetectable viral load [0.23 mg/L (n=30) and 2.3 mg/L (n=16) respectively] than in patients with detectable viral load [0.11 mg/L (n=38) and 0.6 mg/L (n=17) respectively]. C(trough) levels of IDV (r=-0.45; P<0.0001) and NFV (r=-0.43; P=0.011) were correlated with the concomitant viral load. The more discriminating C(trough) efficacy thresholds were estimated statistically as 0.12 mg/L for IDV and 0.5 mg/L for NFV. When C(trough) values were time-corrected, the C(trough) efficacy thresholds, 8 h after the last intake, were 0.15 mg/L for IDV and 0.65 mg/L for NFV.

CONCLUSIONS

These results support the importance of achieving minimal effective C(trough) to improve the virological efficacy of PI-containing HAART, and specify the target concentrations for IDV and NFV.

GENOPHAR: a randomized study of plasma drug measurements in association with genotypic resistance testing and expert advice to optimize therapy in patients failing antiretroviral therapy

OBJECTIVES

To evaluate the benefits of therapeutic drug monitoring (TDM) in association with genotypic resistance testing and expert advice to optimize therapy in multiexperienced patients infected with HIV-1.

METHODS

Patients with a viral load>1000 HIV-1 RNA copies/mL and an unchanged antiretroviral therapy regimen over the last 3 months were randomized into two groups: a genotypic group (G) and a geno-pharmacological group (GP). Treatment was selected by an expert committee according to genotypic resistance testing (the G and GP groups) and TDM (the GP group) at week 4. Treatment could be modified at each visit according to toxicity, poor virological response and TDM. Results of TDM were withheld from the G group until week 12. The primary endpoint of the study was the percentage of patients with viral load<200 copies/mL at week 12.

RESULTS

A total of 134 patients were randomized in the study, with 67 in each group, and included in the intent-to-treat (ITT) analysis. At baseline, median values were as follows: viral load (log(10) copies/mL): G=4.1, GP=4.0; CD4 cell count (cells/microL): G=292, GP=294; and number of prior drugs: G=7, GP=8. The median number of resistance mutations was five in the G group [nucleoside reverse transcriptase inhibitors (NRTIs)=three; non-nucleoside reverse transcriptase inhibitors (NNRTIs)=one; protease inhibitors (PI)=one] and seven in the GP group (NRTI=four; NNRTI=two; PI=one). At week 8, treatment was adjusted according to the TDM in 13 of the 67 patients in the GP group (19%). By ITT missing equal failure analysis at week 12, and after only one intervention according to plasma concentration results, a viral load<200 copies/mL was achieved in 30 of the 67 patients (45%) in the G group and in 29 of the 67 patients (43%) in the GP group (not significant). In the multivariate analysis, only prior exposure to at least two PIs at baseline gave a poor response to subsequent antiretroviral therapy. At week 24, a viral load<200 copies/mL was achieved in 35 of the 67 patients (52%) in the G group and in 40 of the 67 patients (60%) in the GP group.

CONCLUSIONS

A statistically significant benefit of using TDM was not found in this short-term study where patients appeared to be adherent. However, combining genotypic resistance testing with the use of an expert committee to monitor subsequent therapy individually in patients with multiple resistance mutations was associated with high antiviral efficacy.

Benefit of treatment interruption in HIV-infected patients with multiple therapeutic failures: a randomized controlled trial (ANRS 097)

BACKGROUND

Both highly potent antiretroviral drug rescue therapy and treatment interruption have been suggested to be effective in patients with multiple treatment failure.

OBJECTIVE

To assess both the benefits and risks of an 8-week treatment interruption associated with a six to nine-drug rescue regimen in patients with multiple treatment failures.

DESIGN

A randomized comparative controlled trial in 19 university hospitals in France.

PATIENTS

Sixty-eight HIV-infected patients with multiple previous treatment failures and CD4 cell counts less than 200 x 10(6) cells/l and plasma HIV-1-RNA levels of 50,000 copies/ml or greater.

MEASUREMENTS

The primary efficacy outcome was the proportion of patients with at least a 1 log10 decrease (copies/ml) in the plasma HIV-1-RNA level after 12 weeks of therapy.

RESULTS

Treatment interruption followed by multidrug salvage therapy led to a greater proportion of patients achieving virological success (i.e. 1 log10 decrease) at 12 weeks compared with patients receiving multidrug therapy alone (62 versus 26%, intent-to-treat analysis; P = 0.007). The median decrease in the HIV-1-RNA level was -1.91 and -0.37 log10 copies/ml (P = 0.008), respectively. Treatment interruption led to an increase in the number of sensitive drugs of the multidrug regimen (71 versus 35% of regimen with at least two sensitive drugs; P = 0.004). Factors associated with virological success were treatment interruption, the reversion of at least one mutation to wild type, adequate plasma drug concentration, and the use of lopinavir.

CONCLUSION

Treatment interruption was beneficial for treatment-experienced HIV-infected patients with advanced HIV disease and multidrug-resistant virus.

Plasma Levels of Indinavir and Nelfinavir at Time of Virologic Response May Have a Different Impact on the Risk of Further Virologic Failure in HIV-Infected Patients

Indinavir and nelfinavir plasma levels were studied in 407 patients having plasma HIV RNA <500 copies/mL after 4 months of treatment with these drugs. For each drug, an observed/predicted (O/P) ratio was calculated between individual and mean time-adjusted population plasma drug levels. The relationship between the O/P ratio and the risk of rebound of plasma HIV RNA >500 copies/mL beyond month 4 was studied using Cox proportional hazard models. Median follow-up was 20 months. There was no association between indinavir plasma levels and risk of virologic rebound, whereas low nelfinavir + M8 (active nelfinavir metabolite) plasma levels were associated with a higher risk of virologic rebound. In multivariate analysis, the adjusted relative hazard of virologic rebound for patients with an O/P ratio of nelfinavir + M8 metabolite <0.8 compared with others was 2.2 (P = 0.01). In some patients, plasma levels of nelfinavir sufficient to achieve early viral response may not be sufficient to maintain it in the long term. This may be related to insufficient compliance with dietary recommendations. Monitoring of nelfinavir plasma levels thus seems useful, even in patients having early virologic response.

Determination of protease inhibitors using liquid chromatography-tandem mass spectrometry

A method for the analysis of six protease inhibitors and one metabolite has been developed and validated. Amprenavir, ritonavir, saquinavir, lopinavir, indinavir, nelfinavir, and an active metabolite of nelfinavir (M8) are quantitated using reversed-phase liquid chromatography coupled to tandem mass spectrometry, equipped with an electrospray ionization source (ESI-LC-MS-MS). The validation data presented here shows that the method allows the rugged analysis of these species from one aliquot. The evolution of complex drug interactions assessments and the clinical use of therapeutic drug monitoring for these antiretrovirals will be a potential immediate application of this method.

Simultaneous determination of five HIV protease inhibitors nelfinavir, indinavir, ritonavir, saquinavir and amprenavir in human plasma by LC/MS/MS

A sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS-MS) method has been developed to measure the levels of five HIV protease inhibitors nelfinavir (NFV), indinavir (IDV), ritonavir (RTV), saquinavir (SQV) and amprenavir (APV) in human plasma. The analytes and internal standard are isolated from plasma by a simple acetonitrile precipitation of plasma proteins followed by centrifugation. LC-MS-MS in positive mode used pairs of ions at m/z of 568.4/330.0, 614.3/421.2, 720.9/296.0, 671.1/570.2 and 505.9/245.0 for NFV, IDV, RTV, SQV and APV, respectively and 628/421 for the internal standard. Two 1/x weighted linear calibration curves for each analyte were established for quantitation with the low curve ranging from 5 to 1000 ng/ml and while the high curve ranging from 1000 to 10,000 ng/ml. Mean inter- and intra-assay coefficients of variation (CVs) over the ranges of the standard curves were less than 10%. The overall recovery of NFV, IDV, RTV, SQV and APV were 88.4, 91.4, 92.2, 88.9 and 87.6%, respectively.

Pharmacokinetic and other drug interactions in patients with AIDS

A variety of medications are used in treating patients infected with the human immunodeficiency virus (HIV). These medications are used to control viremia and to prevent and treat opportunistic infections. An individual is often required to take numerous drugs at the same time and thus clinicians are confronted with potential drug interactions, some of which are significant. Three different groups of anti-HIV drugs are used to treat patients. These groups include nucleoside reverse transcription inhibitors, non-nucleoside reverse transcription inhibitors, and protease inhibitors. This article reviews the most relevant drug interactions that occur during the treatment of HIV-infected patients with traditional and also alternative drugs. The role of therapeutic drug monitoring in the routine management of HIV-infected patients is discussed.

High-performance liquid chromatography of HIV protease inhibitors in human biological matrices

Methods for HPLC analysis of protease inhibitors (PIs) in human biological matrices were reviewed. Assays have been developed for analysis of single PIs or for simultaneous measurement of multiple PIs in plasma-serum, saliva, cerebrospinal fluid and semen. Liquid-liquid extraction was most often applied for sample pretreatment, but solid-phase extraction and protein precipitation were used as well. Reversed-phase or ion-pair chromatography have been used to separate PIs. Detection of PIs should be sensitive enough for quantitation of plasma concentrations below trough levels of single PIs, or below proposed therapeutic thresholds for PIs. The large majority of assays employs UV detection. As the potential for interferences is large, the selectivity of every method should be evaluated properly. The available high-performance liquid chromatography (HPLC) methods have been applied in clinical pharmacokinetic studies and for therapeutic drug monitoring of PIs. Participation in an interlaboratory quality control program is recommended for every laboratory engaged in the bioanalysis of PIs.

Value of patient self-report and plasma human immunodeficiency virus protease inhibitor level as markers of adherence to antiretroviral therapy: relationship to virologic response

Three methods of adherence to antiretroviral therapy were evaluated for 149 patients infected with human immunodeficiency virus (HIV): plasma level of protease inhibitors (PIs), patient self-report, and routine biological parameters associated with the use of some antiretroviral drugs. Adherence to therapy was estimated from a score calculated from answers to a self-administered questionnaire and on the basis of measurement of relevant plasma and blood levels. Of the 149 patients, 112 had a virologic response, and 122 had adequate trough PI levels. Plasma PI levels and virologic outcome were significantly correlated (P<.0001). The adherence score was significantly correlated with virologic response (P<.001). Macrocytosis was significantly associated with virologic response in the patients treated with zidovudine or stavudine (P=.006). PI level was the higher significant predictor of virologic response (P=.0003). Self-reported adherence (P=.01) and macrocytosis (P=.05) were also independently associated with antiretroviral efficacy.