Indinavir Plasma Concentration and Adherence Score Are Codeterminant of Early Virologic Response in HIV-Infected Patients of the APROCO Cohort

Prolonged exposure to lopinavir impairs endothelium-dependent hyperpolarization-mediated relaxation in rat mesenteric arteries

Protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors are effective antiretroviral drugs, but their use is associated with a high incidence of cardiovascular disease. As vascular dysfunction precedes cardiovascular events, this study aimed to examine the vascular effects of clinically used PIs (indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, and tipranavir) and non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine). Rat mesenteric arteries were suspended in conventional organ chambers for isometric tension recording. Efavirenz, indinavir, nelfinavir, ritonavir, and tipranavir, but not saquinavir and nevirapine, caused endothelium-independent relaxations. Lopinavir induced both endothelium-dependent and -independent relaxations; the former was inhibited by nitric oxide (NO) synthase inhibitor. Incubation with lopinavir for 24 hours reduced relaxations attributable to endothelium-derived hyperpolarization. Relaxations to the adenosine triphosphate-sensitive potassium (K(ATP)) channel opener, levcromakalim, but not those to the NO donor, sodium nitroprusside, were also inhibited. Western blotting indicated that the protein expressions of intermediate (IK(Ca)) and small (SK(Ca)) conductance calcium-activated potassium channels and K(ATP) channel were reduced in mesenteric arteries incubated with lopinavir for 24 hours. In conclusion, lopinavir differs from other PIs in that it acutely induces endothelium-derived NO-mediated relaxation. However, prolonged exposure to lopinavir impairs relaxations, likely by reducing the expressions of IK(Ca), SK(Ca), and K(ATP) channels.

Pharmacokinetics of antiretroviral drugs in anatomical sanctuary sites: the male and female genital tract

HIV resides within anatomical 'sanctuary sites', where local drug exposure and viral dynamics may differ significantly from the systemic compartment. Suboptimal antiretroviral concentrations in the genital tract may result in compartmentalized viral replication, selection of resistant mutations and possible re-entry of wild-type/resistant virus into the systemic circulation. Therefore, achieving adequate antiretroviral exposure in the genital tract has implications for the prevention of sexual and vertical transmission of HIV. Penetration of antiretrovirals in the genital tract is expressed by accumulation ratios derived from the measurement of drug concentrations in time-matched seminal plasma/cervicovaginal fluid and plasma samples. Penetration varies by gender and may be drug (as opposed to class) specific with high interindividual variability. Concentrations in seminal plasma are highest for nucleoside analogues and lowest for protease inhibitors and efavirenz. Seminal accumulation of newer agents, raltegravir and maraviroc, is moderate (rank order of accumulation is nucleoside/nucleotide reverse transcriptase inhibitors [lamivudine/zidovudine/tenofovir/didanosine > stavudine/abacavir] > raltegravir > indinavir/maraviroc/nevirapine >> efavirenz/protease inhibitors [amprenavir/atazanavir/darunavir > lopinavir/ritonavir > saquinavir] > enfuvirtide). In the female genital tract, the nucleoside analogues exhibit high accumulation ratios, whereas protease inhibitors have limited penetration; however, substantial variability exists between individuals and study centres. Second generation non-nucleoside reverse transcriptase inhibitor etravirine, and maraviroc and raltegravir, demonstrate effective accumulation in cervicovaginal secretions (rank order of accumulation is nucleoside/nucleotide reverse transcriptase inhibitor [zidovudine/lamivudine/didanosine > emtricitabine/tenofovir] > indinavir > maraviroc/raltegravir/darunavir/etravirine > nevirapine/abacavir > protease inhibitors [amprenavir/atazanavir/ritonavir] > lopinavir/stavudine/efavirenz > saquinavir).

Benefit of therapeutic drug monitoring of protease inhibitors in HIV-infected patients depends on PI used in HAART regimen--ANRS 111 trial

As a result of high inter-patient variability, and efficacy-concentration and toxicity-concentration relationships, optimization of HIV-protease inhibitor (PI) doses based on plasma concentrations could be beneficial. During a 48-week open prospective non-randomized interventional study of 115 protease inhibitor-naïve patients initiating an indinavir/ritonavir- or lopinavir/ritonavir-, or nelfinavir-containing therapy, protease inhibitor dose was modified when plasma trough concentrations (C(trough)) at weeks 2, 8, 16 and 24 were outside predefined optimal concentration ranges. Failure of the strategy was defined as the proportions of patients with HIV-RNA above 200 copies/mL from weeks 24 to 48 and/or experiencing grades 2, 3 or 4 PI-related adverse events during the study; proportion of patients with last C(trough) measurement outside the concentration range was determined at each visit. Virological failure and/or occurrence of adverse event were observed in 37/94 assessable patients (39%; 95% CI: 29.4-50.0). In the on-treatment analysis, failure of the strategy was noted in 16% of indinavir/r- or lopinavir/r-treated patients (8/51; 95% CI: 7.0-28.6; virological failure: 2; adverse event: 6) but in 44% of nelfinavir-treated patients (11/25; 95% CI: 24.4-65.1; virological failure: 10; adverse event: 1); C(trough) concentrations outside the range were less frequent at the last measurement than at W2 (41% vs. 66%; P < 0.05), with proportions of 35% for indinavir/r- or lopinavir/r-treated patients, but 57% for nelfinavir-treated patients. The proposed strategy of therapeutic drug monitoring may be beneficial to indinavir/r- and lopinavir/r-treated patients, but failed to move concentrations into the predefined range and to produce the expected virological success for nelfinavir-treated patients.

Influence of pharmacogenetics on indinavir disposition and short-term response in HIV patients initiating HAART

AIMS

To assess the relationship between genetic polymorphisms and indinavir pharmacokinetic variability and to study the link between concentrations and short-term response or metabolic safety.

METHODS

Forty protease inhibitor-naive patients initiating highly active antiretroviral therapy (HAART) including indinavir/ritonavir and enrolled in the COPHAR 2-ANRS 111 trial were studied. At week 2, four blood samples were taken before and up to 6 h following drug intake. A population pharmacokinetic analysis was performed using the stochastic approximation expectation maximization (SAEM) algorithm implemented in MONOLIX software. The area under the concentration-time curve (AUC) and maximum (C(max)) and trough concentrations (C(trough)) of indinavir were derived from the population model and tested for their correlation with short-term viral response and safety measurements, while for ritonavir, these same three parameters were tested for their correlation with short-term biochemical safety

RESULTS

A one-compartment model with first-order absorption and elimination best described both indinavir and ritonavir concentrations. For indinavir, the estimated clearance and volume of distribution were 22.2 L/h and 97.3 L, respectively. The eight patients with the *1B/*1B genotype for the CYP3A4 gene showed a 70% decrease in absorption compared to those with the *1A/*1B or *1A/*1A genotypes (0.5 vs. 2.1, P = 0.04, likelihood ratio test by permutation). The indinavir AUC and C(trough) were positively correlated with the decrease in human immunodeficiency virus RNA between week 0 and week 2 (r = 0.4, P = 0.03 and r = -0.4, P = 0.03, respectively). Patients with the *1B/*1B genotype also had a significantly lower indinavir C(max) (median 3.6, range 2.1-5.2 ng/mL) than those with the *1A/*1B or *1A/*1A genotypes (median 4.4, range 2.2-8.3 ng/mL) (P = 0.04) and a lower increase in triglycerides during the first 4 weeks of treatment (median 0.1, range -0.7 to 1.4 vs. median 0.6, range -0.5 to 1.7 mmol/L, respectively; P = 0.02). For ritonavir, the estimated clearance and volume of distribution were 8.3 L/h and 60.7 L, respectively, and concentrations were not found to be correlated to biochemical safety. Indinavir and ritonavir absorption rate constants were found to be correlated, as well as their apparent volumes of distribution and clearances, indicating correlated bioavailability of the two drugs.

CONCLUSION

The CYP3A4*1B polymorphism was found to influence the pharmacokinetics of indinavir and, to some extent, the biochemical safety of indinavir.

A Randomized Controlled Trial of Therapeutic Drug Monitoring in Treatment-Naive and -Experienced HIV-1-Infected Patients

OBJECTIVE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Indinavir Trough Concentration as a Determinant of Early Nephrolithiasis in HIV-1-Infected Adults

Indinavir plasma levels are associated with antiretroviral efficacy; however, little data are available regarding toxicity. We assessed the relationship between indinavir pharmacokinetic (PK) characteristics and severe nephrolithiasis as well as other severe or serious adverse reactions. Patients included in the ANRS CO8 APROCO-COPILOTE cohort and receiving 800 mg indinavir three times daily as a first-line protease inhibitor were eligible for this study. To be included in the analysis, their plasma sample at month 1 (M1) had to be available (n = 282) to estimate using population PK modeling, indinavir PK characteristics, ie, maximum (Cmax) and trough plasma (Cres) concentrations, area under the curve (AUC), and observed/predicted concentration ratio (CR). A Cox model was used to estimate the independent effect of Cmax, Cres, AUC, and CR on the hazard of severe nephrolithiasis and serious adverse reactions. At M1, median Cmax was 6205 ng/mL, Cres 631 ng/mL, AUC 24,242 ng . h/mL, and CR 0.6. After a median follow up of 12 months, 11% of patients (30 of 282) had experienced at least one serious adverse reaction among which 12 were nephrolithiasis. In the multivariate analyses, early high indinavir Cres (ie, >/=1000 ng/mL at M1) was associated with a higher rate of severe nephrolithiasis (hazard ratio = 6.7; 95% confidence interval = 1.8-25.2; P < 0.01) and was also associated with a higher rate of all serious adverse reactions but only when nephrolithiasis were included among those cases. Prospective and early indinavir Cres determination should be recommended in the patient's care management and dosage adjustments.

Adherence and plasma drug concentrations are predictors of confirmed virologic response after 24-week salvage highly active antiretroviral therapy

Data from 197 patients for whom highly active antiretroviral therapy (HAART) failed, who started a new regimen chosen under the guide of resistance testing results interpreted by experts, were retrospectively studied, provided that at least 2 determinations of adherence and plasma drug concentrations were performed during the follow-up. Univariate and multivariable logistic regression analyses were conducted, using confirmed virologic response at week 24 as outcome measure (i.e., achievement of undetectable HIV plasma viral load at any time point before week 24 and its maintenance up to week 24). Suboptimal drug concentrations (odds ratio [OR]: 0.3; 95% confidence interval [CI] 0.2-0.7; p = 0.006) and suboptimal adherence (OR: 0.4; 95% CI 0.2-0.8; p = 0.014) were both negative independent predictors of sustained virologic response, while the use of boosted protease inhibitor-containing regimens resulted to be protective (OR: 2.4; 95% CI 1.1-5.3; p = 0.032).

Hair versus plasma concentrations as indicator of indinavir exposure in HIV-1-infected patients treated with indinavir/ritonavir combination

Large intra-individual variability in plasma levels may limit the interest of therapeutic drug monitoring based on a single determination. Indinavir concentrations were determined both in plasma and hair samples, and correlated with concomitant plasma HIV-RNA in 43 HIV-infected patients. In multivariate analysis, significant association was found between HIV-RNA below 50 copies/ml and indinavir concentrations in hair but not in plasma, suggesting that hair concentrations gave more extensive information on drug exposure than a single plasma sample.