Impact of different low-dose ritonavir regimens on lipids, CD36, and adipophilin expression

Atherosclerotic Cardiovascular Disease and Anti-Retroviral Therapy

In the current era of available therapy for human immunodeficiency virus (HIV), life expectancy for persons living with HIV (PLWH) nears that of the general population. Atherosclerotic cardiovascular disease (ASCVD) has become a particular burden for PLWH and society at large. PLWH have historically been shown to have an excess of cardiovascular risk and subsequent events when compared to the general population. Potential explanations include the increased prevalence of traditional risk factors, direct inflammatory and immunological effects from the HIV virus itself, and metabolic adverse effects of anti-retroviral therapy (ART). Over the past few years, there has been building evidence that chronic inflammation and immune activation independent of virologic suppression contribute significantly to excess ASCVD risk. Although independent agents and combination therapies have varying metabolic effects, the evidence from major randomized controlled trials (RCTs) supports the benefits of early initiation of ART. In this review, we will discuss the epidemiology of ASCVD in HIV-infected patients compared with the general population, give an overview of potential pathogenesis of high-risk plaque in HIV-infected patients, discuss different metabolic effects of individual anti-retrovirals, and discuss the limitations in current screening models for assessing cardiovascular disease (CVD) risk and future directions for treatment.

The pharmacokinetic interaction between ivacaftor and ritonavir in healthy volunteers

AIMS

The aim of this study was to determine the pharmacokinetic interaction between ivacaftor and ritonavir.

METHODS

A liquid chromatography mass spectrometry (LC-MS) method was developed for the measurement of ivacaftor in plasma. An open-label, sequential, cross-over study was conducted with 12 healthy volunteers. Three pharmacokinetic profiles were assessed for each volunteer: ivacaftor 150 mg alone (study A), ivacaftor 150 mg plus ritonavir 50 mg daily (study B), and ivacaftor 150 mg plus ritonavir 50 mg daily after two weeks of ritonavir 50 mg daily (study C).

RESULTS

Addition of ritonavir 50 mg daily to ivacaftor 150 mg resulted in significant inhibition of the metabolism of ivacaftor. Area under the plasma concentration-time curve from time 0 to infinity (AUC_{0-inf obv} ) increased significantly in both studies B and C compared to study A (GMR [95% CI] 19.71 [13.18-31.33] and 19.77 [14.0-27.93] respectively). Elimination half-life (t_1/2 ) was significantly longer in both studies B and C compared to study A (GMR [95% CI] 11.14 [8.72-13.62] and 9.72 [6.68-12.85] respectively). There was no significant difference in any of the pharmacokinetic parameters between study B and study C.

CONCLUSION

Ritonavir resulted in significant inhibition of the metabolism of ivacaftor. These data suggest that ritonavir may be used to inhibit the metabolism of ivacaftor in patients with cystic fibrosis (CF). Such an approach may increase the effectiveness of ivacaftor in 'poor responders' by maintaining higher plasma concentrations. It also has the potential to significantly reduce the cost of ivacaftor therapy.

Response by gender of HIV-1-infected subjects treated with abacavir/lamivudine plus atazanavir, with or without ritonavir, for 144 weeks

Purpose

The 144-week results of the open-label, multicenter Atazanavir/Ritonavir Induction with Epzicom Study (ARIES) were stratified by gender to compare treatment responses.

Methods

A total of 369 HIV-infected, antiretroviral-naïve subjects receiving once-daily abacavir/lamivudine + atazanavir/ritonavir (ATV/r) whose HIV-1 RNA was <50 copies/mL by week 30 were randomized 1:1 at week 36 to maintain or discontinue ritonavir for 108 subsequent weeks. Between- and within-treatment gender-related efficacy and safety differences were analyzed.

Results

Subjects were 85% male; 64% white; and had a mean age of 39 years, baseline median HIV-1 RNA of 114,815 copies/mL, and median CD4+ cell count of 198 cells/mm³. Gender (ATV [n=189]: 29 females/160 males; ATV/r [n=180]: 25 females/155 males) and most other demographics were similar between groups; more females than males were black (65% vs 25%) and fewer females had baseline HIV-1 RNA ≥100,000 copies/mL (41% vs 58%). At week 144, no significant differences between genders were observed in proportion maintaining HIV-1 RNA <50 copies/mL (ATV, 79% vs 77%; ATV/r, 60% vs 75%) or <400 copies/mL (ATV, 83% vs 84%; ATV/r, 68% vs 82%) (intent-to-treat-exposed: time to loss of virologic response analysis); median CD4+ change from baseline (ATV, +365 vs +300 cells/mm³; ATV/r, +344 vs +301 cells/mm³); proportion with treatment-related grade 2–4 adverse events (baseline to week 144: ATV, 41% vs 31%; ATV/r, 36% vs 43%; weeks 36 to 144: ATV, 14% vs 13%; ATV/r, 24% vs 23%); or proportion developing fasting lipid changes. Female and male virologic failure rates (ATV, 0 vs 5; ATV/r, 2 vs 4) and proportions completing the study were similar during the extension phase. Primary withdrawal reasons were loss to follow-up and pregnancy for females and loss to follow-up and other for males.

Conclusion

Over 144 weeks, no significant gender differences were observed in efficacy, safety, or fasting lipid changes with abacavir/lamivudine +ATV or abacavir/lamivudine +ATV/r.

Treatment response to unboosted atazanavir in combination with tenofovir disoproxil fumarate and lamivudine in human immunodeficiency virus-1-infected patients who have achieved virological suppression: A therapeutic drug monitoring and pharmacogenetic study

BACKGROUND/PURPOSE

Treatment response to switch regimens containing unboosted atazanavir and tenofovir disoproxil fumarate (TDF)/lamivudine guided by therapeutic drug monitoring in human immunodeficiency virus-infected patients is rarely investigated.

METHODS

Consecutive patients with plasma human immunodeficiency virus RNA load < 200 copies/mL switching to unboosted atazanavir plus zidovudine-lamivudine (coformulated), abacavir-lamivudine (coformulated), or TDF/lamivudine > 3 months were included for determinations of treatment response, plasma atazanavir concentrations, and single-nucleotide polymorphisms of MDR1, PXR, and UGT1A1 genes from 2010 to 2014. Treatment failure was defined as either discontinuation of atazanavir for any reason or plasma viral load ≥ 200 copies/mL within 96 weeks.

RESULTS

During the study period, 128 patients switched to unboosted atazanavir with TDF/lamivudine (TDF group) and 186 patients switched to unboosted atazanavir with two other nucleoside reverse-transcriptase inhibitors (non-TDF group). There were no statistically significant differences in the distributions of single-nucleotide polymorphisms of MDR1 (2677 and 3435), PXR genotypes (63396), and UGT1A1*28 between the two groups. Recommended plasma atazanavir concentrations were achieved in 83.5% and 64.9% of the TDF group and non-TDF group, respectively (p < 0.01). After a median follow-up duration of 96.0 weeks, treatment failure occurred in 19 (14.9%) and 34 (18.3%) patients in the TDF group and non-TDF group, respectively (p = 0.60). Low-level viremia (40-200 copies/mL) before switch (adjusted hazard ratio, 2.12; 95% confidence interval, 1.12-4.01) and without therapeutic drug monitoring (adjusted hazard ratio, 2.08; 95% confidence interval, 1.16-3.73) were risk factors for treatment failure.

CONCLUSION

Switch to unboosted atazanavir with TDF/lamivudine achieves a similar treatment response to that with two other nucleoside reverse-transcriptase inhibitors in patients achieving virological suppression with the guidance of therapeutic drug monitoring.

Clinical use of cobicistat as a pharmacoenhancer of human immunodeficiency virus therapy

The pharmacoenhancement of plasma concentrations of protease inhibitors by coadministration of so-called boosters has been an integral part of antiretroviral therapy for human immunodeficiency virus (HIV) for 1.5 decades. Nearly all HIV protease inhibitors are combined with low-dose ritonavir or cobicistat, which are able to effectively inhibit the cytochrome-mediated metabolism of HIV protease inhibitors in the liver and thus enhance the plasma concentration and prolong the dosing interval of the antiretrovirally active combination partners. Therapies created in this way are clinically effective regimens, being convenient for patients and showing a high genetic barrier to viral resistance. In addition to ritonavir, which has been in use since 1996, cobicistat, a new pharmacoenhancer, has been approved and is widely used now. The outstanding property of cobicistat is its cytochrome P450 3A-selective inhibition of hepatic metabolism of antiretroviral drugs, in contrast with ritonavir, which not only inhibits but also induces a number of cytochrome P450 enzymes, UDP-glucuronosyltransferase, P-glycoprotein, and other cellular transporters. This article reviews the current literature, and compares the pharmacokinetics, pharmacodynamics, and safety of both pharmacoenhancers and discusses the clinical utility of cobicistat in up-to-date and future HIV therapy.

Cobicistat: a Novel Pharmacoenhancer for Co-Formulation with HIV Protease and Integrase Inhibitors

Human immunodeficiency virus (HIV) therapy has evolved over the last 20 years from mono-drug therapy given five times daily to regimens consisting of three or four drugs combined in a single-tablet dosed once daily. To allow once-daily administration, several drugs require pharmacokinetic boosting by a concomitantly administered P-glycoprotein and cytochrome P450 inhibitor such as ritonavir. The availability of cobicistat provides an alternative to ritonavir to those who are intolerant to this drug, and the opportunity for co-formulated single-tablet regimens consisting of tenofovir/emtricitabine, cobicistat and elvitegravir, atazanavir or darunavir. The cobicistat/elvitegravir-based regimen is well tolerated and patients achieved high rates of HIV RNA suppression in clinical trials. Cobicistat inhibits renal tubular secretion of creatinine, resulting in increased serum creatinine concentrations and reduced estimated glomerular filtration rate, with a new set point reached after 4 weeks. Treatment limiting renal toxicity with cobicistat/elvitegravir and tenofovir disoproxil fumarate is infrequent and may be further reduced when cobicistat is co-formulated with tenofovir alafenamide fumarate, a novel formation of tenofovir currently undergoing clinical trials.

Inflammatory biomarker changes and their correlation with Framingham cardiovascular risk and lipid changes in antiretroviral-naive HIV-infected patients treated for 144 weeks with abacavir/lamivudine/atazanavir with or without ritonavir in ARIES

Propensity for developing coronary heart disease (CHD) is linked with Framingham-defined cardiovascular risk factors and elevated inflammatory biomarkers. Cardiovascular risk and inflammatory biomarkers were evaluated in ARIES, a Phase IIIb/IV clinical trial in which 515 antiretroviral-naive HIV-infected subjects initially received abacavir/lamivudine + atazanavir/ritonavir for 36 weeks. Subjects who were virologically suppressed by week 30 were randomized 1:1 at week 36 to either maintain or discontinue ritonavir for an additional 108 weeks. Framingham 10-year CHD risk scores (FRS) and risk category of <6% or ≥6%, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) were assessed at baseline, week 84, and week 144. Biomarkers were stratified by FRS category. When ritonavir-boosted/nonboosted treatment groups were combined, median hsCRP did not change significantly between baseline (1.6 mg/liter) and week 144 (1.4 mg/liter) in subjects with FRS <6% (p=0.535) or with FRS ≥6% (1.9 mg/liter vs. 2.0 mg/liter, respectively; p=0.102). Median IL-6 was similar for subjects with FRS <6% (p=0.267) at baseline (1.6 pg/ml) and week 144 (1.4 pg/ml) and for FRS ≥6% (2.0 pg/ml vs. 2.2 pg/ml, respectively; p=0.099). Median Lp-PLA(2) decreased significantly (p<0.001) between baseline (197 nmol/min/ml) and week 144 (168 nmol/min/ml) in subjects with FRS <6% and with FRS ≥6% (238 nmol/min/ml vs. 175 nmol/min/ml, respectively; p<0.001). In conclusion, in antiretroviral-naive subjects treated with abacavir-based therapy for 144 weeks, median inflammatory biomarker levels for hsCRP and IL-6 generally remained stable with no significant difference between baseline and week 144 for subjects with either FRS <6% or FRS ≥6%. Lp-PLA(2) median values declined significantly over 144 weeks for subjects in either FRS stratum.

Effect of adherence as measured by MEMS, ritonavir boosting, and CYP3A5 genotype on atazanavir pharmacokinetics in treatment-naive HIV-infected patients

We investigated population pharmacokinetics and pharmacogenetics of ritonavir-boosted atazanavir (ATV), using drug intake times exactly recorded by the Medication Event Monitoring System. The ANRS 134-COPHAR 3 trial was conducted in 35 HIV-infected treatment-naive patients. ATV (300 mg), ritonavir (100 mg), and tenofovir (300 mg) + emtricitabine (200 mg), in bottles with MEMS caps, were taken once daily for 6 months. Six blood samples were collected at week 4 to measure drug concentrations, and trough levels were measured bimonthly. A model integrating ATV and ritonavir pharmacokinetics and pharmacogenetics used nonlinear mixed effects. Use of exact dosing data halved unexplained variability in ATV clearance. The ritonavir-ATV interaction model suggested that optimal boosting effect is achievable at lower ritonavir exposures. Patients with at least one copy of the CYP3A5*1 allele exhibited 28% higher oral clearance. We provide evidence that variability in ATV pharmacokinetics is defined by adherence, CYP3A5 genotype, and ritonavir exposure.

Ritonavir boosting dose reduction from 100 to 50 mg does not change the atazanavir steady-state exposure in healthy volunteers

OBJECTIVES

To evaluate the pharmacokinetics, tolerability and safety of 300 mg of atazanavir boosted with 100 or 50 mg of ritonavir, both once daily, at steady state.

METHODS

This was a single-blind, multiple-dose, crossover, sequence-randomized trial. Thirteen healthy HIV-1-negative men received witnessed once-daily doses of atazanavir (300 mg) and 100 or 50 mg of ritonavir for 10 days (15 day washout). Atazanavir and ritonavir plasma concentrations were determined for 24 h on day 10. Log-transformed individual pharmacokinetic parameters were compared between treatments (analysis of variance); the difference between treatments on the log scale and 95% CIs were calculated. Fasting cholesterol, triglycerides, glucose and bilirubin plasma levels were measured at the beginning and end of each period and compared (Wilcoxon signed rank test). Gastrointestinal symptoms and other events were recorded.

RESULTS

Ritonavir C(max) and the AUC₀₋₂₄ were lower after the 50 mg booster dose than after 100 mg [geometric mean ratio (GMR) (95% CI), 0.40 (0.31-0.51) and 0.35 (0.29-0.42), respectively]. No differences were observed in atazanavir exposure with 50 or 100 mg of ritonavir [GMR C(max) (95% CI), 1.00 (0.79-1.28); GMR AUC₀₋₂₄ (95% CI), 0.98 (0.79-1.21)]. Atazanavir trough concentration was >0.15 mg/L in all volunteers. Total and low-density lipoprotein cholesterol increased 0.40 mM (P = 0.01) and 0.37 mM (P = 0.003) from their corresponding baseline value during the 100 mg dosing period; there were no significant changes on 50 mg. Mild increases in bilirubin were detected on day 10 after both treatments without differences between treatments.

CONCLUSIONS

In spite of higher exposure to ritonavir with 100 mg, atazanavir exposure was equivalent; the lipid profile was better under the lower booster dose (50 mg).

A randomized comparative 96-week trial of boosted atazanavir versus continued boosted protease inhibitor in HIV-1 patients with abdominal adiposity

BACKGROUND

Abdominal adiposity in HIV-1 patients initiating antiretroviral therapy may be part of a restoration-to-health phenomenon. Lipoatrophy is associated with long-term thymidine analogue therapy. Individual protease inhibitors (PIs) differ in their effects on lipids and insulin resistance.

METHODS

A randomized open-label multicentre 96-week trial compared changes in fat distribution in patients with suppressed HIV-1 RNA and abdominal adiposity, who either continued on their current twice-daily ritonavir-boosted PI (PI/r) or switched to once-daily boosted atazanavir (ATV/r). Treatment with two nucleoside reverse transcriptase inhibitors was unchanged. Body composition was assessed by dual-energy x-ray absorptiometry (DEXA) and abdominal computerized tomography (CT) scanning.

RESULTS

In total, 201 patients were randomized; 131 switched to ATV/r. Viral suppression (<50 copies/ml) was similarly maintained (93% ATV/r versus 89% PI/r). Mean changes from baseline in trunk-to-limb fat ratio were similar; difference estimates 0.03 (95% CI -0.06, 0.12; P=0.48 at week 48) and 0.02 (95% CI -0.10, 0.14; P=0.73 at week 96). More patients in the PI/r arm had a decrease of ≥20% in limb fat from baseline at week 96. Significantly greater reductions in proatherogenic lipids occurred following switch to ATV/r. Both treatment regimens were generally well-tolerated; the incidence of grade 3-4 treatment-related clinical adverse events was 34% among ATV/r recipients versus 4% of PI/r-treated patients.

CONCLUSIONS

Switching to ATV/r had no demonstrable benefit on abdominal adiposity. Maintenance of efficacy, less limb fat loss and marked reduction in proatherogenic lipids was observed with ATV/r compared with continuing a PI/r regimen.

Effects of ritonavir-boosted darunavir, atazanavir and lopinavir on adipose functions and insulin sensitivity in murine and human adipocytes

BACKGROUND

Ritonavir-boosted protease inhibitors (PIs) could adversely affect metabolism and adipose tissue to different extents, depending on the molecule. Using drugs with minimal adverse metabolic effects is an important consideration in at-risk HIV-infected patients. In vitro adipocyte models can be useful for comparing the effects of different PIs.

METHODS

We compared the effects of darunavir, darunavir/ritonavir, atazanavir/ritonavir and lopinavir/ritonavir in murine and human adipocytes on differentiation, mitochondrial function, reactive oxygen species (ROS) production and insulin sensitivity.

RESULTS

In human and murine adipocytes, differentiation evaluated by lipid content and protein expression of adipogenic markers, mitochondrial function evaluated by aggregation of the cationic dye JC-1 and by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide lysis, and mitochondrial mass evaluated by MitoTracker fluorescence and the expression of mitochondrial proteins were unaffected by darunavir, mildly affected by darunavir/ritonavir and further altered by atazanavir/ritonavir and lopinavir/ritonavir. ROS production was unaltered by darunavir and darunavir/ritonavir but was increased by lopinavir/ritonavir and atazanavir/ritonavir. Regarding insulin sensitivity, darunavir and darunavir/ritonavir had no significant effect on insulin activation of protein kinase B (Akt/PKB) and MAP kinase and of glucose transport, whereas lopinavir/ritonavir and atazanavir/ritonavir partly impaired the effect of insulin. The effect of atazanavir/ritonavir was generally milder than that of lopinavir/ritonavir.

CONCLUSIONS

The various PIs differentially modified adipocyte functions. Darunavir alone did not affect adipocyte functions and only modestly altered differentiation and mitochondrial function when associated with ritonavir. Lopinavir/ritonavir adversely affected differentiation and lipid content, mitochondrial function, ROS production and insulin sensitivity, and the effect of atazanavir/ritonavir was intermediate. Thus, in vitro, darunavir/ritonavir presented a safer metabolic profile on adipocytes than atazanavir/ritonavir and lopinavir/ritonavir.

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.