Pharmacokinetics and Pharmacodynamics of Darunavir and Etravirine in HIV-1-Infected, Treatment-Experienced Patients in the Gender, Race, and Clinical Experience (GRACE) Trial

Pharmacokinetics of Antiretroviral Drugs in Older People Living with HIV: A Systematic Review

BACKGROUND AND OBJECTIVE

The life expectancy of people living with HIV (PLWHIV) has significantly improved in recent decades, mostly due to antiretroviral (ARV) therapy. Aging can affect the pharmacokinetics of drugs and, as a consequence, increase the risk of drug interactions and toxicity that may impact treatment. The aim of this study was to carry out a systematic review of the literature on the effect of aging on ARV pharmacokinetics.

METHODS

Searches were performed in the BVS, EMBASE and PUBMED databases until November 2022. All studies available in English, Spanish and Portuguese investigating the pharmacokinetics of ARV approved by the US Food and Drug Administration (FDA) from 2005 to 2020 were selected. Peer-reviewed publications were included if they met all criteria: adults (≥ 18 years of age) living with or without HIV; report any pharmacokinetic parameter or plasma concentration of at least one of the following ARVs: tenofovir alafenamide fumarate (TAF); doravirine (DOR), rilpivirine (RIL) and etravirine (ETR); darunavir (DRV), tipranavir (TPV) and fostemsavir (FTR); dolutegravir (DTG), raltegravir (RAL), bictegravir (BIC) and elvitegravir (EVG); maraviroc (MVC); ibalizumab (IBA); cobicistat (COBI). Pharmacokinetic parameters were reported stratified per age group: young adults (aged 18-49 years) or older (age ≥ 50 years) and all studies were evaluated for quality. The review protocol was registered in the PROSPERO database (registration number CRD42021236432).

RESULTS

Among 97 studies included, 20 reported pharmacokinetic evaluation in older individuals (age ≥ 50 years). Twenty five percent of the articles were phase I randomized clinical trials with HIV-negative participants and non-compartmental pharmacokinetic analysis presenting the parameters area under the curve (AUC) and peak drug concentration (Cmax). Seven age-stratified studies evaluated BIC, ETR, DRV, DTG, DOR and RAL. We found publications with discordant results for ETR and DTG pharmacokinetics in different age groups. DRV exposure was highly variable but modestly increased in aging PLWHIV. In contrast, no influence of age on BIC, DOR and RAL exposure was observed. A variability in pharmacokinetic parameters could be observed for the other ARVs (TAF and MVC) in different age groups.

CONCLUSION

Exposure to DRV increases modestly with age, while exposure to BIC, DOR and RAL appears to be unaffected by age. As the available evidence to confirm a potential effect of aging on ARV pharmacokinetics is limited, further studies are necessary.

Population Pharmacokinetic Analysis of Darunavir and Tenofovir Alafenamide in HIV-1-Infected Patients on the Darunavir/Cobicistat/Emtricitabine/Tenofovir Alafenamide Single-Tablet Regimen (AMBER and EMERALD Studies)

The single-tablet regimen darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg has undergone phase III studies AMBER (NCT02431247) and EMERALD (NCT02269917) in HIV-infected patients. An existing population pharmacokinetic (PopPK) model for cobicistat-boosted darunavir (DRV) was updated to describe DRV PK in AMBER and EMERALD. For TAF, a PopPK model was developed using richly sampled phase I/II data and updated with sparsely sampled AMBER data. Individual exposure metrics for DRV and TAF in patients receiving D/C/F/TAF were derived (AMBER, n=356; EMERALD, n=750). The DRV PopPK model is a two-compartment model with sequential zero-order, first-order input. TAF PK is described by a one-compartment model with dual parallel input for absorption (slow and fast pathway). DRV covariates were α1-acid-glycoprotein and body weight. TAF covariates were lean body weight and α1-acid-glycoprotein. DRV and TAF PK were unaffected by age, race, or gender. Estimated DRV mean (SD) C_0h and AUC_24h, respectively, were 1899 (759) ng/mL and 87,909 (20,232) ng*h/mL in AMBER; 1813 (859) ng/mL and 85,972 (22,413) ng*h/mL in EMERALD. Estimated TAF mean (SD) AUC_24h was 132 (41) ng*h/mL. These PK parameters were in line with historical data. No apparent relationships of DRV or TAF exposure with efficacy (virologic response) or safety (metabolic, cardiac, liver, gastrointestinal, skin, bone, renal, pancreas, lipid events) parameters were seen. Additionally, our findings demonstrate that in patients with low plasma concentrations, there is no risk of decreased virologic response or virologic rebound. This supports the use of a once-daily, single-tablet regimen of D/C/F/TAF 800/150/200/10 mg for the treatment of HIV-1-infected subjects.

Exploration of Reduced Doses and Short-Cycle Therapy for Darunavir/Cobicistat in Patients with HIV Using Population Pharmacokinetic Modeling and Simulations

BACKGROUND AND OBJECTIVES

Protease inhibitors such as darunavir are an important therapeutic option in the anti-human immunodeficiency virus arsenal. Current dosage guidelines recommend using cobicistat- or ritonavir-boosted darunavir 800 mg every 24 h (q24h) in protease inhibitor-naïve patients, or ritonavir-boosted darunavir 600 mg q12h in experienced patients. However, darunavir displays a large, poorly characterized, inter-individual pharmacokinetic variability. The objectives of this study were to investigate the pharmacokinetics of darunavir and to elucidate the sources of its inter-individual variability using population pharmacokinetic modeling. Then, to determine the appropriateness of current treatment guidelines and the feasibility of alternative dosing regimens in a representative cohort of adult patients using simulations.

METHODS

Sparse pharmacokinetic samples were collected in 127 patients with human immunodeficiency virus type 1 infection, then supplemented with rich sampling data from a subset of 12 individuals. Data were analyzed using the nonlinear mixed-effects modeling software NONMEM. The effect of reduced doses (600 mg q24h and 400 mg q24h) or reduced frequency of administration (800 mg q24h for 5 days followed by 2 days of treatment interruption) was simulated.

RESULTS

Our model adequately described the pharmacokinetics of darunavir. Predictors of individual exposure were CYP3A5*3 and SLCO3A1 rs8027174 genotypes, sex, and alpha-1 acid glycoprotein level. No relationship was apparent between darunavir area under the curve and treatment efficacy or safety. For reduced dose regimens, darunavir concentrations remained above the protein binding-corrected EC₅₀ in the majority of subjects. More stringent pharmacokinetic targets were not reached in a significant proportion of patients.

CONCLUSIONS

These results add to the growing body of evidence that darunavir-based therapy could be simplified to reduce costs and toxicity, as well as to improve patient compliance. However, the heterogeneity in pharmacokinetic response should be considered when assessing whether individual patients could benefit from a particular regimen, for instance through the use of population pharmacokinetic models.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03101644, date of registration: 5 April, 2017.

Darunavir concentration in PBMCs may be a better indicator of drug exposure in HIV patients

PURPOSE

The clinical efficacies of some antiretroviral drugs are known to not depend on its concentration in blood. To establish a method of dosage adjustment for darunavir (DRV) based on pharmacokinetic theory, we analyzed the correlation between DRV levels in peripheral blood mononuclear cells (PBMCs) and plasma.

METHODS

The concentrations of DRV and ritonavir (RTV) in plasma and PBMCs of 31 samples obtained from 19 patients were analyzed. An in vitro kinetic study using MOLT-4 cells was performed to assess the contribution of RTV to the intracellular accumulation of DRV.

RESULTS

DRV levels in PBMCs varied between 7.91 and 29.36 ng/10⁶ cells (CV 37.5%), while those in plasma were greater. No significant correlation was found between the trough level of DRV in plasma and that in PBMCs (p = 0.575). The inter-day difference in DRV levels in PBMCs seemed smaller than that in plasma (- 41.6-23.0% vs - 83.3-109.1%). In the in vitro study, the elimination half-life of cellular efflux of DRV was 15.7 h in the absence of RTV and extended to 47.6 h in the presence of RTV.

CONCLUSIONS

We found a poor correlation between intracellular DRV and plasma DRV levels in patients receiving highly active antiretroviral therapy. The efflux rate of DRV from cells was slow; therefore, the concentration of DRV in PBMCs may reflect average exposure to the drug and clinical efficacy.

Therapeutic drug monitoring in treatment-experienced HIV-infected patients receiving darunavir-based salvage regimens: A case series

Therapeutic drug monitoring (TDM) constitutes a compelling approach for the optimization of antiretroviral therapy in treatment-experienced HIV-1 patients. While various inhibitory indices have been proposed to predict virologic outcome, there is a lack of consensus on the clinical value of TDM. Here, we report the comparative results of TDM in 14 HIV-1-infected patients who had previously received at least two different PI-based regimens and who initiated darunavir (DRV)-based salvage therapy. Pharmacokinetic/pharmacodynamics (PK/PD) parameters were calculated for each subject. Seventy-nine percent of subjects had a viral load <50 copies/mL at 48 weeks. The only subject with two consecutive viral loads >50 copies/mL at the end of the study period was the patient with the lowest instantaneous inhibitory potential (IIP). The sample size was insufficient to show an association between any of the PK/PD parameters and virologic response. Based on our observations, we suggest that the utility of IIP for antiretroviral combinations for the prediction of virologic outcome in HIV-1 drug-experienced patients should be studied further.

Impact of obesity on antiretroviral pharmacokinetics and immuno-virological response in HIV-infected patients: a case-control study

Background

Obesity has high prevalence among HIV-infected patients. Increased adipose tissue mass affects the pharmacokinetics of numerous drugs, but few data are available for antiretroviral drugs.

Objectives

In this study we aimed to explore the pharmacokinetics of antiretroviral drugs and the immuno-virological response in obese patients with HIV infection.

Patients and methods

We examined data from 2009 to 2012 in our hospital's database for HIV-1-infected patients who received an antiretroviral drug (abacavir, emtricitabine, lamivudine, tenofovir, efavirenz, etravirine, nevirapine, atazanavir/ritonavir, darunavir/ritonavir, lopinavir/ritonavir or raltegravir). Obese patients were defined as those with BMI ≥30 kg/m 2 and normal-weight patients as those with BMI 19-25 kg/m 2 . Plasma concentrations ( C 12/24 ) were compared for each antiretroviral drug using a Mann-Whitney test. Suboptimal dosing and virological outcome were assessed by logistic regression, adjusting on covariates.

Results

We enrolled 291 obese and 196 normal-weight patients. Among the 12 analysed antiretroviral drugs, tenofovir, efavirenz and lopinavir C 12 values were significantly lower in obese than normal-weight patients: 66 versus 86 ng/mL, 1498 versus 2034 ng/mL and 4595 versus 6420 ng/mL, respectively ( P  <   0.001). Antiretroviral drug C 12/24 values were more frequently below efficacy thresholds for obese than for normal-weight patients after adjustment for other covariates ( P  <   0.001). Although obese patients showed a higher CD4 count than normal-weight patients (510 versus 444 cells/mm 3 , P  <   0.001), the groups did not differ in virological failure rate.

Conclusions

This study highlights the impact of obesity on antiretroviral drug plasma exposure, but identifies no consequence of this suboptimal exposure on the immuno-virological control in this population.

Pharmacokinetic Evaluation of Darunavir Administered Once or Twice Daily in Combination with Ritonavir or the Three-Direct-Acting Antiviral Regimen of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir in Adults Coinfected with Hepatitis C and Human Immunodeficiency Viruses

The three-direct-acting antiviral (3D) regimen containing ombitasvir, paritaprevir, ritonavir, and dasabuvir with or without ribavirin (RBV) is approved for treatment of hepatitis C virus (HCV) genotype 1 (GT1)/human immunodeficiency virus type 1 (HIV-1) coinfection. Results of a pharmacokinetic substudy of 3D and darunavir are presented. HCV/HIV-1-coinfected subjects were randomized to maintain an antiretroviral regimen with darunavir at 800 mg once daily (QD) or switched to a regimen with darunavir at 600 mg twice daily (BID). On study day 1, subjects received 3D and RBV plus darunavir for 12 weeks. Pharmacokinetic parameters were compared for darunavir and ritonavir with and without 3D (week 4 and day -1). Pharmacokinetic parameters of 3D were compared to historical data. Ten subjects received darunavir QD, and 12 subjects received darunavir BID. The central value ratios (90% confidence interval [CI]) for maximum concentrations (C_max), area under the plasma concentration-time curve between 0 and 24 h postdose (AUC₂₄), and trough plasma concentration at 24 h postdose (C₂₄) of darunavir administered QD with 3D versus administration of darunavir alone were 0.92 (0.72, 1.18), 0.83 (0.71, 0.98), and 0.64 (0.44, 0.93), respectively. The ratios (90% CI) for darunavir C_max, AUC₁₂, and C₁₂ administered BID with 3D were 0.92 (0.76, 1.12), 0.88 (0.73, 1.05), and 0.73 (0.58, 0.92), respectively. Exposures of 3D were similar to or slightly lower than those in historical data. All darunavir trough concentrations (C_trough) associated with an HIV-1 RNA level of >40 copies/ml were above the darunavir 50% effective concentration (EC₅₀) of 550 ng/ml for resistant virus. In conclusion, the 3D regimen with darunavir QD or BID did not affect darunavir C_max and AUC, whereas the darunavir C_trough decreased. Changes in pharmacokinetic parameters of 3D were not considered clinically significant. Episodes of intermittent HIV-1 viremia were infrequent and were not associated with darunavir C_trough values below 550 ng/ml. (This study has been registered at ClinicalTrials.gov under identifier NCT01939197.).

Etravirine combined with antiretrovirals other than darunavir/ritonavir for HIV-1-infected, treatment-experienced adults: Week 48 results of a phase IV trial

Objective:

VIOLIN (TMC125IFD3002; NCT01422330) evaluated the safety, tolerability, and pharmacokinetics of etravirine with antiretrovirals other than darunavir/ritonavir in HIV-1-infected patients.

Methods:

In a 48-week, phase IV, single-arm, multicenter study, patients on prior antiretroviral therapy (⩾8 weeks) who needed to change regimen for virologic failure (viral load ⩾ 500 copies/mL) or simplification/adverse events (viral load < 50 copies/mL) received etravirine 200 mg bid with ⩾1 other active antiretroviral, excluding darunavir/ritonavir or only nucleoside/tide reverse transcriptase inhibitors.

Results:

Of 211 treated patients, 73% (n = 155) had baseline viral load ⩾ 50 copies/mL and 27% (n = 56) had baseline viral load < 50 copies/mL. Protease inhibitors were the most common background antiretrovirals (83%). Diarrhea was the most frequent adverse event (17%). Serious adverse events (no rash) occurred in 5% of patients; none were etravirine related. Overall, median etravirine AUC_12h was 5390 ng h/mL and C_0h was 353 ng/mL (N = 199). Week 48 virologic response rates (viral load < 50 copies/mL; Food and Drug Administration Snapshot algorithm) were 48% (74/155) (baseline viral load ⩾ 50 copies/mL) and 75% (42/56) (baseline viral load < 50 copies/mL). Virologic failure rates were 42% and 13%, respectively. The most frequently emerging etravirine resistance-associated mutations in virologic failures were Y181C, E138A, and M230L. Virologic response rates for patients with baseline viral load ⩾ 50 copies/mL were 38% (30/79) (non-adherent) versus 64% (44/69) (adherent subset).

Conclusion:

Etravirine 200 mg bid in combination with antiretrovirals other than darunavir/ritonavir was well tolerated in the studied treatment-experienced HIV-1-infected population. The overall etravirine safety and tolerability profile and pharmacokinetics (specifically in those patients who were adherent) were similar to those previously observed for etravirine in HIV-1-infected adults. The relatively high level of non-adherence, also observed in the pharmacokinetic assessments, negatively impacted virologic response, especially in patients with ⩾50 copies/mL at baseline.

Interaction between Darunavir and Etravirine Is Partly Mediated by CYP3A5 Polymorphism

OBJECTIVES

To assess the impact of the loss-of-function CYP3A5*3 allele (rs776746, 6986A>G SNP) on darunavir (DRV) plasma concentrations.

METHODS

135 HIV-1 infected patients treated with DRV-based therapy were included in the study and plasma samples were obtained immediately before drug intake in order to determine DRV trough concentrations using an ultra performance liquid chromatography method (UPLC) with diode-array detection (DAD). Noteworthy is the fact that in 16 (11.9%) patients, etravirine (ETR) was combined with DRV. CYP3A5 genotypes were determined using real time PCR method (TaqMan® genotyping assay). The patients were then classified into CYP3A5 expressors (CYP3A5*1 allele carriers) and non-expressors (CYP3A5*3 homozygous). Subsequently, the association between DRV plasma trough concentration ([DRV]plasma) and CYP3A5 genotype-based expression status was analyzed.

RESULTS

45% of the patients were classified as CYP3A5 expressors. In the whole cohort, mean [DRV]plasma was not different between CYP3A5 expressors and non-expressors (1894ng/ml [CI95%: 1566-2290] versus 1737ng/ml [CI95%: 1468-2057], p = 0.43). However, in the subgroup of the 16 patients receiving DRV combined with ETR, a significantly lower [DRV]plasma was observed for CYP3A5 expressors when compared to non-expressors (1385ng/ml [CI95%:886.3-2165] versus 3141ng/ml [CI95%:2042-4831], p = 0.007).

CONCLUSIONS

Interaction between DRV and ETR is partly mediated by CYP3A5 polymorphism with lower DRV plasma trough concentrations in CYP3A5 expressors suggesting a specific ETR-driven CYP3A5 activation only in CYP3A5 expressors. Consequently, these patients might be more at risk of infra-therapeutic [DRV]plasma. This potentially important observation is a good illustration of a genotype-based drug interaction, which could also have considerable consequences if translated to other CYP3A5-metabolized drugs. Further investigations are thus needed to confirm this association and to explore its clinical impact, mainly in the African population among whom CYP3A5 expressors are more frequent, before recommending systematic CYP3A5 pre-emptive genotyping for DRV-ETR co-administration.

Etravirine Pharmacokinetics in HIV-Infected Pregnant Women

Background: The study goal was to describe etravirine pharmacokinetics during pregnancy and postpartum in HIV-infected women.

Methods: IMPAACT P1026s and PANNA are on-going, non-randomized, open-label, parallel-group, multi-center phase-IV prospective studies in HIV-infected pregnant women. Intensive steady-state 12-h pharmacokinetic profiles were performed from 2nd trimester through postpartum. Etravirine was measured at two labs using validated ultra performance liquid chromatography (detection limits: 0.020 and 0.026 mcg/mL).

Results: Fifteen women took etravirine 200 mg twice-daily. Etravirine AUC_0–12 was higher in the 3rd trimester compared to paired postpartum data by 34% (median 8.3 vs. 5.3 mcg*h/mL, p = 0.068). Etravirine apparent oral clearance was significantly lower in the 3rd trimester of pregnancy compared to paired postpartum data by 52% (median 24 vs. 38 L/h, p = 0.025). The median ratio of cord blood to maternal plasma concentration at delivery was 0.52 (range: 0.19–4.25) and no perinatal transmission occurred.

Conclusion: Etravirine apparent oral clearance is reduced and exposure increased during the third trimester of pregnancy. Based on prior dose-ranging and safety data, no dose adjustment is necessary for maternal health but the effects of etravirine in utero are unknown. Maternal health and infant outcomes should be closely monitored until further infant safety data are available.

Clinical Trial registration: The IMPAACT protocol P1026s and PANNA study are registered at ClinicalTrials.gov under NCT00042289 and NCT00825929.

Pharmacokinetics of Once-Daily Darunavir/Ritonavir With and Without Etravirine in Human Immunodeficiency Virus-Infected Children, Adolescents, and Young Adults

BACKGROUND

Limited data are available for once-daily (QD) darunavir (DRV)/ritonavir (r) in the pediatric population. Coadministration of etravirine (ETR) may alter the pharmacokinetics (PK) of DRV. We evaluated the PK interactions between DRV/r (QD) and ETR QD or twice-daily (BID) in children, adolescents, and young adults.

METHODS

Human immunodeficiency virus-infected subjects 9 to < 24 years old on optimized background therapy including DRV/r 800/100 mg QD alone or combined with ETR 200 mg BID or ETR 400 mg QD were enrolled. Protocol-defined target drug exposure ranges based on adult data were used to assess the adequacy of each regimen. Intensive 24-hour blood sampling was performed, and PK parameters were determined using noncompartmental analysis.

RESULTS

Thirty-one subjects (14 males) completed the study; 16 received DRV/r QD alone (group 1), 6 received DRV/r plus ETR BID (group 2A), and 9 received DRV/r plus ETR QD (group 2B). The geometric mean (90% confidence interval [CI] geometric mean) for DRV area under the curve at 24 hours (AUC24) was 57.9 (49.6-67.6), 74.9 (44.4-126.5), and 66.4 (50.8-86.9) mg × h/L for patients in groups 1, 2A, and 2B, respectively. The increased DRV exposure when coadministered with ETR was not statistically significant. The geometric mean (90% CI geometric mean) of ETR AUC24 was 8.6 (4.4-16.8) and 11.9 (7.5-18.9) mg × h/L for groups 2A and 2B, respectively, with comparable C24.

CONCLUSIONS

The results suggest that DRV/r QD with ETR 400 mg QD or 200 mg BID is appropriate and support further evaluation of the safety and efficacy of the once-daily regimen in older children, adolescents, and young adults.

Darunavir and ritonavir total and unbound plasmatic concentrations in HIV-HCV-coinfected patients with hepatic cirrhosis compared to those in HIV-monoinfected patients

Our objective was to describe the pharmacokinetic (PK) parameters of total and unbound darunavir and ritonavir concentrations in HIV-hepatitis C virus (HCV)-coinfected patients with cirrhosis, as ritonavir-boosted darunavir is mainly metabolized in the liver, and hepatic cirrhosis might modify darunavir-ritonavir concentrations. This was a prospective, case-control, and unicenter study. HIV-HCV-coinfected patients with compensated cirrhosis (cases) and HIV-monoinfected patients with normal liver function (controls) were included. Darunavir-ritonavir was given at 800/100 mg once daily. Patients were followed for 24 weeks to assess safety and efficacy. A steady-state 12-h PK study was performed. Total and unbound concentrations were determined by liquid chromatography-tandem mass spectrometry. The unbound fraction was obtained by ultrafiltration. The plasma area under the concentration-time curve (AUC) and oral clearance (CL/F) were assessed by noncompartmental models. Thirty patients (20 cases and 10 controls) were included. Among cirrhotic patients, the Child-Pugh score was C in 4 cases, B in 1 case, and A in 15 cases; the median (interquartile range) transient elastography values were 20 kPa (14 to 26 kPa), and 5 patients had prior clinical decompensations. There were no significant differences in the darunavir PK parameters between cases and controls except for longer time to maximum plasma concentrations (Tmax) and half-lives in the cirrhotic patients. There were no significant differences in ritonavir total concentrations, but the unbound concentrations were higher in cirrhotic patients. There were significant correlations between the darunavir total and unbound concentrations in both cirrhotic patients and controls. There were no differences in PK parameters based on Child-Pugh score, liver elasticity, gender, or use of concomitant medications. In conclusion, in HIV-HCV-coinfected patients with clinically compensated cirrhosis receiving darunavir-ritonavir at 800/100 mg once daily, the darunavir total and unbound concentrations are similar to those observed in noncirrhotic patients, and dose adjustments are not necessary.

Darunavir: a review of its use in the management of HIV-1 infection

The latest HIV-1 protease inhibitor (PI) darunavir (Prezista™) has a high genetic barrier to resistance development and is active against wild-type HIV and HIV strains no longer susceptible to some older PIs. Ritonavir-boosted darunavir, as a component of antiretroviral therapy (ART), is indicated for the treatment of HIV-1 infection in adult and paediatric patients (aged ≥3 years), with or without treatment experience (details vary depending on region of approval). Several open-label or partially-blinded trials have evaluated the efficacy of ritonavir-boosted darunavir ART regimens for up to 192 weeks in these settings. In treatment-naïve adults, once-daily boosted darunavir was no less effective in establishing virological suppression than once- or twice-daily boosted lopinavir, yet was more effective at maintaining suppression long term. Moreover, treatment-experienced adults with no darunavir resistance-associated mutations (RAMs) had no less effective viral load suppression with once-daily than with twice-daily boosted darunavir. In treatment-experienced adults, including some with multiple major PI RAMs, twice-daily boosted darunavir was more effective than twice-daily boosted lopinavir or boosted control PIs in reducing viral load, and provided virological benefit as part of a salvage regimen in those with few remaining treatment options. Boosted darunavir also reduced viral load when administered once-daily in treatment-naïve adolescents or twice-daily in treatment-experienced children and adolescents. Boosted darunavir is generally well tolerated, with gastrointestinal disturbances and lipid abnormalities among the most common tolerability issues. It has a lipid profile more favourable than that of boosted lopinavir in terms of total cholesterol and triglyceride changes and, when administered once daily, its lipid effects are generally similar to those of boosted atazanavir. Thus, boosted darunavir is a useful option for the ART regimens of adult and paediatric patients with HIV-1 infection.

Pharmacokinetics of etravirine in HIV-infected patients concomitantly treated with rifampin for tuberculosis

Etravirine is metabolized by three cytochrome P450 enzymes that are in turn induced by rifampin. Consequently, co-administration of etravirine and rifampin is not recommended. To date, however, no clinical studies exploring the drug-drug interaction of this combination have been conducted. Here we report two cases of off-label etravirine use concurrently with antitubercular treatment, dictated by the unavailability of other treatments. Plasma drug concentrations were monitored by regular measurements. Our results appear to confirm the increased metabolism of etravirine through the induction of cytochrome P450 enzymes, but the adequacy of drug levels in all of the measurements and subsequent virological suppression suggest that this drug interaction may not be clinically relevant.

Caring for women living with HIV: gaps in the evidence

Introduction

In the management of HIV, women and men generally undergo the same treatment pathway, with gender differences being given limited consideration. This is in spite of accumulating evidence that there are a number of potential differences between women and men which may affect response to treatment, pharmacokinetics, toxicities and coping. There are also notable psychological, behavioural, social and structural factors that may have a unique impact on women living with HIV (WLWH). Despite our increasing knowledge of HIV and advances in treatment, there are significant gaps in the data relating specifically to women. One of the factors contributing to this situation is the under-representation of women in all aspects of HIV clinical research. Furthermore, there are clinical issues unique to women, including gynaecologic and breast diseases, menopause-related factors, contraception and other topics related to women's and sexual health.

Methods

Using scoping review methodology, articles from the literature from 1980 to 2012 were identified using appropriate MeSH headings reflecting the clinical status of WLWH, particularly in the areas of clinical management, sexual health, emotional wellbeing and treatment access. Titles and abstracts were scanned to determine whether they were relevant to non-reproductive health in WLWH, and papers meeting inclusion criteria were reviewed.

Results

This review summarizes our current knowledge of the clinical status of WLWH, particularly in the areas of clinical management, sexual health, emotional wellbeing and treatment access. It suggests that there are a number of gender differences in disease and treatment outcomes, and distinct women-specific issues, such as menopause and co-morbidities, that pose significant challenges to the care of WLWH.

Conclusions

Based on a review of this evidence, outstanding questions and areas where further studies are required to determine gender differences in the efficacy and safety of treatment and other clinical and psychological issues specifically affecting WLWH have been identified. Well-controlled and adequately powered clinical studies are essential to help provide answers to these questions and to contribute to activities aimed at improving the health and wellbeing of WLWH.

Non-nucleoside reverse transcriptase inhibitors: a review on pharmacokinetics, pharmacodynamics, safety and tolerability

INTRODUCTION

Human immunodeficiency virus (HIV) type-1 non-nucleoside and nucleoside reverse transcriptase inhibitors (NNRTIs) are key drugs of highly active antiretroviral therapy (HAART) in the clinical management of acquired immune deficiency syndrome (AIDS)/HIV infection.

DISCUSSION

First-generation NNRTIs, nevirapine (NVP), delavirdine (DLV) and efavirenz (EFV) are drugs with a low genetic barrier and poor resistance profile, which has led to the development of new generations of NNRTIs. Second-generation NNRTIs, etravirine (ETR) and rilpivirine (RPV) have been approved by the Food and Drug Administration and European Union, and the next generation of drugs is currently being clinically developed. This review describes recent clinical data, pharmacokinetics, metabolism, pharmacodynamics, safety and tolerability of commercialized NNRTIs, including the effects of sex, race and age differences on pharmacokinetics and safety. Moreover, it summarizes the characteristics of next-generation NNRTIs: lersivirine, GSK 2248761, RDEA806, BILR 355 BS, calanolide A, MK-4965, MK-1439 and MK-6186.

CONCLUSIONS

This review presents a wide description of NNRTIs, providing useful information for researchers interested in this field, both in clinical use and in research.

Insights on GRACE (Gender, Race, And Clinical Experience) from the patient's perspective: GRACE participant survey

The Gender, Race And Clinical Experience (GRACE) study was conducted between October 2006 and December 2008 to evaluate sex- and race-based differences in outcomes after treatment with a darunavir/ritonavir-based antiretroviral regimen. Between June 2010 and June 2011, former participants of the GRACE trial at participating sites were asked to complete a 40-item questionnaire as part of the GRACE Participant Survey study, with a primary objective of assessing patients' characteristics, experiences, and opinions about participation in GRACE. Of 243 potential survey respondents, 151 (62%) completed the survey. Respondents were representative of the overall GRACE population and were predominantly female (64%); fewer were black, and more reported recreational drug use compared with nonrespondents (55% vs. 62% and 17% vs. 10%, respectively). Access to treatment (41%) and too many blood draws (26%) were reported as the best and worst part of GRACE, respectively. Support from study site staff was reported as the most important factor in completing the study (47%). Factors associated with nonadherence, study discontinuation, and poor virologic response in univariate analyses were being the primary caregiver for children, unemployment, and transportation difficulties, respectively. Patients with these characteristics may be at risk of poor study outcomes and may benefit from additional adherence and retention strategies in future studies and routine clinical care.

Clinical pharmacokinetics of antiretroviral drugs in older persons

INTRODUCTION

Combination antiretroviral therapy has enabled HIV-infected persons to reach older ages in high numbers. Hepatic and renal changes that normally occur with advancing age occur earlier and with higher incidence in HIV-infected individuals. A limited number of prospective controlled studies have demonstrated small reductions (17 to 41%) in lopinavir, atazanavir and lamivudine clearance in older versus younger adults. A much larger number of retrospective studies in adults (age range ∼ 20 to 60 years), including all antiretroviral drugs, have evaluated age as a covariate for pharmacokinetics. Most studies did not detect substantial associations between drug exposures and age.

AREAS COVERED

This review summarizes antiretroviral drug pharmacokinetics in older persons. The authors review articles from PubMed (search terms: elderly, antiretroviral, pharmacokinetics) in addition to the bibliographies of those selected.

EXPERT OPINION

The evidence to date does not support major pharmacokinetic changes in adults between ∼ 20 and 60 years of age. However, additional prospective, well-controlled studies are needed in more persons > 60 years, including those with frailty and comorbidities, with assessment of unbound drug clearance, and incorporation of adherence, pharmacogenetics and concomitant medications. Until then, guidelines for drug-drug interactions and dosing in renal and hepatic impairment should be followed in older HIV-infected individuals.