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Background: In the ANRS 165 DARULIGHT study (NCT02384967) carried out in HIV-infected patients, the use of a darunavir/ritonavir-containing regimen with a switch to a reduced dose of darunavir maintained virological efficacy (≤50 copies/mL) for 48 weeks with a good safety profile., Objectives: To assess the total and unbound blood plasma pharmacokinetics of darunavir and associated antiretrovirals, and their penetration into semen before and after dose reduction., Patients and Methods: Patients receiving a darunavir/ritonavir (800/100 mg q24h)-containing regimen for >6 months with plasma HIV-RNA ≤50 copies/mL for >12 months were switched to 400/100 mg darunavir/ritonavir q24h at week 0. A 24 h intensive pharmacokinetic blood sampling and a trough seminal sampling were performed before (week 0) and after (week 12) dose reduction. Individual pharmacokinetic parameter estimates were obtained using non-linear mixed-effect modelling for darunavir/ritonavir in blood plasma and used to test for bioequivalence, whereas darunavir/ritonavir in seminal plasma and NRTIs were analysed using a non-compartmental approach., Results and Conclusions: Fifteen patients completed the intensive pharmacokinetic analysis. There was no significant decrease in total and unbound darunavir blood plasma exposure despite a 50% decrease in darunavir daily dose from 800 to 400 mg (AUC0-24 = 65 563 versus 52 518 ng·h/mL; P = 0.25). A decrease in apparent oral clearance (CL/F) of both darunavir and ritonavir at week 12 suggests a modification of the initial darunavir/ritonavir daily dose balance (800/100 to 400/100 mg), in favour of a reduced inducer effect of darunavir on cytochrome P450 and efflux transporters compared with the standard dose.

Background: We aimed at investigating the antiviral activity and the pharmacokinetics of the dual antiretroviral (ARV) combination of rilpivirine plus darunavir/ritonavir 25/800/100 mg once-daily in naïve HIV-1-infected individuals (NHII) with different baseline viral loads., Settings: Pharmacokinetic/pharmacodynamics study in ARV-naïve HIV-infected individuals., Methods: The primary endpoint was the number of NHII with HIV-RNA < 40 copies/mL at week 48. Secondary endpoints included rilpivirine/darunavir/ritonavir pharmacokinetics, HIV-RNA decay, and changes in ECG QT interval., Results: Thirty-six individuals were enrolled, 18 with a baseline viral load < 100,000 copies/mL (group A) and 18 with a baseline viral load > 100,000 copies/mL (group B). All but 1 (HIV-RNA = 63 copies/mL) subjects achieved viral load < 50 copies/mL by week 36, and all at week 48. Median (range) HIV-RNA reduction (Log10 copies/mL) was 1.3 (0.6-1.9) over the first week, with no differences between groups A and B. Geometric mean and 95%CI rilpivirine C max , C trough , AUC were 183 (165-239), 114 (104-109) ng/mL, 2966 (2704-3820) ng h/mL. No QTcF interval changes were recorded., Conclusions: rilpivirine/darunavir/ritonavir could be efficacious, with limited short-term toxicity in ARV-naïve patients. Although rilpivirine was co-administered with ritonavir, its exposure was within ranges measured during phase III trials.

Management of comorbidities and medications is complex in HIV-1-infected patients. The overall objective of this project was to develop separate physiologically based pharmacokinetic (PBPK) substrate models for the protease inhibitors darunavir and lopinavir. These protease inhibitors are used in the treatment of HIV infection. Both darunavir and lopinavir are coadministered with another medication that inhibits cytochrome (CYP) 3A. The current project focused on PBPK modeling for darunavir and lopinavir coadministered with ritonavir. Darunavir and lopinavir PBPK models that accounted for ritonavir CYP3A inhibition effects (linked PBPK models) were developed. The linked PBPK models were then used to predict the effect on darunavir or lopinavir exposure from CYP modulators. In the next step, the predicted effect of hepatic impairment was evaluated. Additional exploratory analyses predicted CYP3A inhibition effects on darunavir or lopinavir exposure in simulated hepatically impaired subjects. The linked PBPK models reasonably predicted darunavir or lopinavir exposure based on simulations with CYP inhibitors or inducers. Exploratory simulations using the linked darunavir or lopinavir PBPK models indicated CYP3A inhibition may further increase darunavir or lopinavir exposure in patients with hepatic impairment., (© 2017, The American College of Clinical Pharmacology.)

Objectives: Cobicistat and ritonavir have different inhibitory profiles for drug transporters that could impact the distribution of co-administered drugs. We compared darunavir concentrations in CSF when boosted by cobicistat versus ritonavir relative to plasma concentrations and with WT HIV-1 IC50 and IC90., Methods: An open, single-arm, sequential clinical trial (NCT02503462) where paired CSF and blood samples were taken from seven HIV-infected patients presenting with HIV-associated neurocognitive disorders (HAND) and treated with a darunavir/ritonavir (800/100 mg) once-daily regimen. Ritonavir was subsequently replaced by cobicistat and paired CSF and blood samples were obtained from the same patients after treatment with the darunavir/cobicistat (800/150 mg) once-daily regimen. Darunavir concentrations at the end of the dosing interval were quantified by LC-MS/MS., Results: The median (IQR) darunavir concentrations in CSF with ritonavir and cobicistat boosting were 16.4 ng/mL (8.6-20.3) and 15.9 ng/mL (6.7-31.6), respectively (P = 0.58). The median (IQR) darunavir CSF:plasma ratios with ritonavir and cobicistat boosting were 0.007 (0.006-0.012) and 0.011 (0.007-0.015), respectively (P = 0.16). Darunavir concentrations in CSF exceeded the darunavir IC50 and IC90 by a median of 9.2- and 6.7-fold with ritonavir boosting, and by 8.9- and 6.5-fold with cobicistat boosting, respectively. All patients had darunavir CSF concentrations above the target inhibitory concentrations and remained virologically suppressed in the CSF and plasma., Conclusions: This small study shows that cobicistat and ritonavir give comparable effective darunavir concentrations in CSF, thus suggesting that these boosters can be used interchangeably in once-daily darunavir regimens., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure., Methods: A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards., Results: The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P  <   0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P  =   0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL ( P  <   0.001), genotypic susceptibility score ≤2 ( P  =   0.001), lower nadir CD4 cell count ( P  =   0.003) and not being in the adherent group ( P  =   0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks., Conclusions: The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Pregnant women are usually excluded from clinical trials. Physiologically based pharmacokinetic (PBPK) modelling may provide a method to predict pharmacokinetics in pregnant women, without the need to perform extensive in vivo clinical trials. Here, we used mechanistic modelling to delineate the potential impact of drug transporters on darunavir pharmacokinetics and to identify current knowledge gaps that limit accurate PBPK modelling of darunavir/ritonavir (darunavir/r) exposure in pregnancy. Simcyp (version 13.2) was used for PBPK modelling, using physicochemical and in vitro pharmacokinetic parameters of darunavir and ritonavir from the literature. The Michaelis-Menten constant (K m) and the maximum rate of metabolite formation (V max) for cytochrome P450 3A4-mediated darunavir biotransformation and inhibition by ritonavir were determined experimentally, while the contributions of hepatocyte influx and efflux transporters were assessed by sensitivity analysis. The simulations were compared with previously published clinical pharmacokinetic data. We found that use of a well-stirred liver model overestimated darunavir exposure substantially. A permeability-limited liver model, including hepatic uptake and efflux transporters and an efficient enterohepatic circulation step, resulted in an acceptable description of darunavir/r exposure. For the 600/100 mg darunavir/r twice-daily dose and the 800/100 mg once-daily dose, the estimated pharmacokinetic parameters were within a 2-fold range of the reported data. The predicted decreases in the area under the concentration-time curve (AUC) values during pregnancy for the twice- and once-daily doses were 27 and 41%, respectively, which were in line with the observed decreases of 17-22 and 33%. In conclusion, our data support a clinically relevant role of hepatic transporters in darunavir pharmacokinetics. By including them in our model, we successfully approximated the increase in darunavir exposure mediated by ritonavir co-administration and the decrease in darunavir exposure observed during pregnancy.

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., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Background: The objective of the study was to assess plasma concentrations of efavirenz, darunavir/ritonavir and raltegravir in patients with human immunodeficiency virus-hepatitis C virus (HIV-HCV)-coinfection without liver cirrhosis., Methods: In this observational, open-label study, adult HIV-infected outpatients treated with tenofovir/emtricitabine plus efavirenz (600 mg daily), darunavir/ritonavir (800/100 mg daily) or raltegravir (400 mg twice daily) for at least 4 weeks were asked to participate. Subjects with liver cirrhosis were excluded. The trough concentration (C trough) of darunavir/ritonavir and raltegravir and the mid-dose concentration (C12h) of efavirenz were assessed at steady state by a validated high-performance liquid chromatography (HPLC)-tandem mass spectrometry method., Results: A total of 96 HIV-positive patients were enrolled into the study. Thirty-four patients were treated with efavirenz, 33 with darunavir/ritonavir and 29 with raltegravir. The geometric mean plasma C trough [coefficient of variation (%)] of darunavir was comparable between HIV+/HCV+ and HIV+/HCV- subjects: 2644 ng/ml (155%) and 2491 ng/ml (139%), respectively (geometric mean ratio (GMR) = 0.81; 95% confidence interval (CI) = 0.79-1.56; p = 0.69). These values were comparable for raltegravir: 108 ng/ml (149%) in the HIV+/HCV+ group and 96 ng/ml (161%) in the HIV+/HCV- group (GMR = 0.84; 95% CI = 0.61-1.44; p = 0.72). On the contrary, the geometric mean plasma C12h of efavirenz was significantly higher among the 15 HIV+/HCV+ patients (1915 ng/ml, 159%) than among the 19 HIV+/HCV- patients (1505 ng/ml, 167%; GMR = 1.41; 95% CI = 1.19-1.71; p = 0.009)., Conclusions: The mean plasma concentration of efavirenz was significantly higher in HCV-positive than in HCV-negative patients without liver cirrhosis, while the mean plasma levels of darunavir/ritonavir and raltegravir were comparable in both groups.

A sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the simultaneous determination of darunavir, ritonavir and tenofovir in human plasma. Sample preparation involved a simple liquid-liquid extraction using 200 μL of human plasma extracted with methyl tert-butyl ether for three analytes and internal standard. The separation was accomplished on an Acquity UPLC BEH C18 (50 mm x 2.1 mm, 1.7 μm) analytical column using gradient elution of acetonitrile/methanol (80:20, v/v) and 5.0 mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4 mL/min. The linearity of the method ranged between 20.0 and 12 000 ng/mL for darunavir, 2.0 and 2280 ng/mL for ritonavir, and 14.0 and 1600 ng/mL for tenofovir using 200 μL of plasma. The method was completely validated for its selectivity, sensitivity, linearity, precision and accuracy, recovery, matrix effect, stability, and dilution integrity. The extraction recoveries were consistent and ranged between 79.91 and 90.04% for all three analytes and internal standard. The method exhibited good intra-day and inter-day precision between 1.78 and 6.27%. Finally the method was successfully applied for human pharmacokinetic study in eight healthy male volunteers after the oral administration of 600 mg darunavir along with 100 mg ritonavir and 100 mg tenofovir as boosters., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This 2-part, phase 1, open-label, randomized, crossover study (NCT00752310) assessed ritonavir-boosted darunavir bioavailability (oral suspension vs. tablets), and steady-state darunavir pharmacokinetics (suspension). Part 1: 20 healthy adults randomly received 3 treatments with a ≥7-day washout between treatments; twice-daily ritonavir (100 mg, days 1-5) with darunavir (600 mg, day 3) as 2 × 300-mg tablets (fed, reference), or 6 mL of a 100-mg/mL suspension (fed or fasted, test). Part 2: 18 healthy volunteers received twice-daily darunavir (suspension, 600 mg days 1-6, one dose day 7) with twice-daily ritonavir (100 mg, days 1-9). Darunavir pharmacokinetics were evaluated (part 1 day 3; part 2 day 7). Safety/tolerability were assessed. In part 1, 90% confidence intervals for darunavir Cmax and AUC were all within 80-125% for suspension (fed or fasted) versus tablets (fed). Steady-state darunavir (suspension) pharmacokinetics in part 2 were similar to historic controls (tablets). No clinically relevant differences in adverse events or laboratory abnormalities occurred between treatments. Darunavir administered as an oral suspension or tablets (both with low-dose ritonavir) showed comparable bioavailability in healthy adults after a single dose. Steady-state darunavir pharmacokinetics (suspension, 600/100 mg twice daily) were consistent with historic controls; this formulation is considered suitable for pediatric use and for adults who cannot swallow tablets., (© 2014, The American College of Clinical Pharmacology.)