Darunavir Plasma Research Articles

Pharmacokinetic profile and safety of adjusted doses of darunavir/ritonavir with rifampicin in people living with HIV.

Darunavir/ritonavir is better tolerated than lopinavir/ritonavir and has a higher genetic barrier to resistance. Co-administration with rifampicin has been contraindicated as a significant reduction in darunavir exposure is expected. This is a barrier to darunavir/ritonavir use where TB is endemic. To evaluate the safety and pharmacokinetic profile of adjusted doses of darunavir/ritonavir with rifampicin. Virally suppressed participants on second-line lopinavir/ritonavir-based ART were switched to darunavir/ritonavir 800/100 mg q24h. In sequence: rifampicin was added; the dose of ritonavir was escalated; and darunavir was increased (darunavir/ritonavir 1600/200 mg q24h and 800/100 mg q12h were given in randomized sequence with rifampicin). Darunavir plasma concentrations were measured on the seventh/last day of each treatment period. To prevent viral rebound, dolutegravir (50 mg q12h) was added during rifampicin administration and for 1 week thereafter. Clinical events, ALT and bilirubin were monitored every 2-3 days during rifampicin administration. A total of 17/28 participants started study treatment. Six (35.3%) were withdrawn for symptomatic hepatitis with severe ALT elevations, developing after 9-11 days of rifampicin and 2-4 days of ritonavir 200 mg. The study was stopped prematurely due to this high rate of hepatotoxicity. Only four participants completed the study. All hepatotoxicity resolved on withdrawal of study treatment. All participants were successfully re-established on their lopinavir/ritonavir-based regimen. After doubling the darunavir/ritonavir doses on rifampicin, darunavir pre-dose concentrations approached those on standard doses without rifampicin for q12h doses, but not for q24h doses. Adjusted doses of darunavir/ritonavir with rifampicin had unacceptable risk of hepatotoxicity. Darunavir trough concentrations were markedly reduced with the daily adjusted dose.

Risk factors contributing to a low darunavir plasma concentration.

Darunavir is an efficacious drug; however, pharmacokinetic variability has been reported. The objective of this study was to find predisposing factors for low darunavir plasma concentrations in patients starting the once‐ or twice‐daily dosage. Darunavir plasma concentrations from January 2010 till December 2014 of human immunodeficiency virus‐infected individuals treated in the outpatient clinic of the University Medical Center Groningen were retrospectively reviewed. The first darunavir plasma concentration of patients within 8 weeks after initiation of darunavir therapy was selected. A dichotomous logistic regression analysis was conducted to select the set of variables best predicting a darunavir concentration below median population pharmacokinetic curve. In total 113 patients were included. The variables best predicting a darunavir concentration besides food intake included age together with estimated glomerular filtration rate (Hosmer–Lemeshow test P = 0.945, Nagelkerke R 2 = 0.284). Systematic evaluation of therapeutic drug monitoring results may help to identify patients at risk for low drug exposure.

O-1 Dosing for two: placental transfer and fetal darunavir exposure

Background Fetal drug exposure during pregnancy can be a determinant of fetal drug toxicity or efficacy. Fetal exposure is usually derived from the cord-to-maternal (ctm) concentration ratio. This static parameter does not provide information on the pharmacokinetics in utero, limiting the assessment of a fetal exposure-effect relationship. Pregnancy physiologically-based pharmacokinetic (p-PB-PK) modelling could provide a solution, although incor-poration of placental transfer remains challenging. Here, we aimed to include placental transfer parameters de-rived from an ex vivo human cotyledon perfusion model into a p-PBPK model, to quantitatively simulate fetal ex-posure to the antiretroviral agent darunavir, co-adminis-tered with ritonavir, at term. Methods An existing and validated p-PBPK model of ma-ternal darunavir/ritonavir exposure was coded in Berkeley Madonna syntax to allow expansion with a feto-placental unit. Bidirectional placental transport of darunavir at term was included. In order to parameterize the model, we determined maternal-to-fetal (mtf) and fetal-to-maternal (ftm) darunavir/ritonavir placental clearances with an ex vivo human cotyledon perfusion model. Simulated ma-ternal PK profiles were compared with observed clinical data to verify the validity of the maternal model aspect. Next, population fetal PK profiles were simulated for different darunavir/ritonavir dosing regimens. These profiles were compared with available cord blood concen-trations in vivo . Additionally, we explored the influence of different DRV/r dosing regimens on fetal exposure and antiviral effects. Results An average (±SD) mtf cotyledon clearance of 0.91±0.11 mL/min and ftm of 1.6±0.3 mL/min was de-termined (n=6 perfusions). Scaled placental transfer was included into a feto-placental unit and integrated in the p-PBPK model. For darunavir 600/100 mg twice daily, the simulated fetal plasma Cmax, Ctrough, Tmax and T1/2 at steady state were; 1.1 mg/L, 0.57 mg/L, 3 hours, and 21 hours, respectively. This indicates that the fetal population Ctrough is above the protein-adjusted EC90 for inhibit-ing the replication of wild type (0.20 mg/L) and around the EC90 for resistant virus (0.55 mg/L). The simulated ftm plasma concentration ratio (range) over a dosing interval was 0.30 (0.16–0.37), compared to a median (range) ratio for observed darunavir ctm plasma ratio of 0.18 (0–0.82; 0 reported if cord blood concentrations were below the lower limit of quantification [ Conclusion A p-PBPK model for maternal darunavir exposure was extended with a feto-placental unit. The simulated fetal darunavir plasma concentrations were in the range of observed cord blood concentrations. This advanced model provides a valuable tool in assessing the implications of new dosing regimens, optimising the safety of maternal pharmacotherapy and fetal antiretro-viral treatment.

Food intake and darunavir plasma concentrations in people living with HIV in an outpatient setting.

AimsPatients receiving darunavir are advised to take it concomitantly with food. The objectives of the present cross‐sectional study were to evaluate the actual concomitant food intake of patients visiting an HIV outpatient clinic.MethodsSixty participants treated with darunavir/ritonavir once daily were subjected to a food recall questionnaire concerning their last concomitant food intake with darunavir. Darunavir trough concentrations were calculated.ResultsThe median food intake was 507 (0–2707) kcal; protein intake, 20 (0–221)g; carbohydrate intake, 62 (0–267)g; fat intake: 14 (0–143)g; and dietary fibre: 4 (0–30)g. Twenty‐five patients (42%) ingested their drug with between‐meal snacks. No relationship was found between food intake and trough concentrations.ConclusionsClear advice on the optimal caloric intake is needed, to avoid high caloric intake in patients who already have an increased risk of cardiovascular disease due to their HIV infection.

Interaction between Darunavir and Etravirine Is Partly Mediated by CYP3A5 Polymorphism.

ObjectivesTo assess the impact of the loss-of-function CYP3A5*3 allele (rs776746, 6986A>G SNP) on darunavir (DRV) plasma concentrations.Methods135 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.Results45% 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).ConclusionsInteraction 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.

Quantification of darunavir and etravirine in human peripheral blood mononuclear cells using high performance liquid chromatography tandem mass spectrometry (LC–MS/MS), clinical application in a cohort of 110 HIV-1 infected patients and evidence of a potential drug–drug interaction

ObjectivesTo describe the validation of a sensitive high performance liquid chromatography tandem mass spectrometry (LC–MS/MS) method allowing the simultaneous quantification of darunavir (DRV) and etravirine (ETR) in peripheral blood mononuclear cells (PBMCs) and its application in a cohort of HIV-1 infected patients. MethodsBlood samples were obtained from 110 patients. PMBCs were isolated using density gradient centrifugation. Drug extraction from PBMCs was performed with a 60:40 methanol–water (MeOH–H2O) solution containing deuterated IS (DRV-d9 and ETR-d8). The chromatographic separation was performed on a RP18 XBridge™ column. ResultsThe geometric mean (GM) of cell associated concentration ([DRV]CC) and plasmatic concentration ([DRV]plasma) were 360.5ng/mL (CI95%:294.5–441.2) and 1733ng/mL (CI95%:1486–2021), respectively. A geometric mean intracellular (IC)/plasma ratio (GMR) of 0.21 (CI95%:0.18–0.24) was calculated. Adjusted for dose/body surface area and post-intake time, a statistically significant correlation was observed between [DRV]Plasma and the eGFR (p=0.002) and between [DRV]Plasma and the concomitant use of ETR (p=0.038). For the 10 patients receiving ETR in addition to DRV, the GM of [ETR]Plasma (available for 8 out of 10 patients) and [ETR]CC were 492.3ng/mL and 2951ng/mL respectively. The GMR of ETR was 7.6 (CI95%: 3.61–13.83). ConclusionsA handy and sensitive high performance LC–MS/MS method allowing the simultaneous quantification of DRV and ETR in PBMCs has been described and successfully applied in the largest cohort of DRV-treated patients reported to date. ETR accumulates more efficiently in PBMCs compared to DRV. We have also highlighted a possible impact of ETR on DRV plasma concentrations requiring further investigations.

Interindividual and Intra-Individual Variabilities of Darunavir and Ritonavir Plasma Trough Concentrations in Multidrug Experienced HIV Patients Receiving Salvage Regimens

There is no consensus on darunavir (DRV) target levels in plasma for clinical use, and information about variability in plasma concentrations is limited. : To investigate the variability in DRV plasma trough concentrations in the clinical setting, evaluating interindividual and intraindividual variabilities of plasma drug levels among HIV-infected patients receiving ritonavir (RTV)-boosted DRV (DRV/r) within salvage regimens, and evaluate the potential correlation between variability and virological response. Sixty-two patients taking DRV/r (600/100 mg twice a day) were evaluated for trough plasma concentrations and immunovirological parameters after 6 months from the start of the regimen. A subgroup of patients (n = 21) was also evaluated for intraindividual variability (expressed as coefficient of variation) on 2 samples taken at different time points. Drug concentrations were assayed by high-performance liquid chromatography with ultraviolet detection, and the values were expressed as medians with interquartile range (IQR). Genotypic sensitivity score and genotypic inhibitory quotient were calculated. DRV/r was used with a median of 3 other antiretroviral drugs (raltegravir use 88.7%). Median plasma concentrations were 3.22 mcg/mL (IQR, 2.04-5.69) for DRV and 0.44 mcg/mL (IQR, 0.21-0.70) for RTV. Both drugs showed a high interindividual variability in plasma concentrations (61% and 99.3%, respectively). Only 3 patients (4.8%) had undetectable DRV plasma levels. DRV plasma concentrations showed a significant positive correlation with age (r = 0.298, P = 0.019), but no significant correlation between DRV genotypic inhibitory quotient and HIV-RNA plasma levels (P = 0.614) was found. Intraindividual coefficients of variation were 58.4% for DRV and 47.1% for RTV. Patients with undetectable HIV-RNA showed a trend for lower intraindividual coefficients of variation compared with patients with detectable HIV-RNA (55.9% versus 83.8%, P = 0.156). No major interaction effects with other antiretroviral drugs were found. In a context of salvage therapy, both DRV and RTV plasma levels showed high interindividual and intraindividual variabilities. Lower intraindividual variability could be beneficial in maintaining viral suppression.

Switching to darunavir/ritonavir 800/100 mg once‐daily containing regimen maintains virological control in fully suppressed pre‐treated patients infected with HIV‐1

The objective of this study was to evaluate the switch to once-daily darunavir/ritonavir 800/100 mg in treatment-experienced patients with suppressed HIV-1 replication on a twice-daily ritonavir-boosted protease-inhibitor (bid PI/r) containing regimen, that is in a setting where genotypic resistance test cannot be performed. In this open label, non-comparative, multicenter study, patients on a bid PI/r-containing triple combination, with suppressed viral replication, were switched to once-daily darunavir/r 800/100 mg containing triple combination. The primary endpoint was the proportion of patients with plasma HIV-RNA < 50 copies/ml 24 weeks after the switch. Intensive darunavir pharmacokinetic evaluation was performed at Week 4 (W4) in 11 patients. Eighty-five patients were enrolled. All had HIV-RNA < 50 copies/ml at screening with a pre-exposure to a median of 2 PI/r (1-5). By intent-to-treat analysis (missing = failure), 78/85 patients (92%, 95% CI [83;96]) maintained an HIV-RNA < 50 copies/ml at W24. Seven patients experienced protocol-defined treatment failure between baseline and W24: Two had confirmed low-level viral rebound, one discontinued study treatment for adverse event, three withdrew their consent, and one was lost to follow-up. By on-treatment analysis, 78/80 patients (97%, 95% CI [91;99]) maintained an HIV-RNA < 50 copies/ml at W24. Results were similar at Week 48. The median area under the darunavir plasma concentration-time curve measured in 11 patients was 61,380 ng hr/ml; darunavir median trough concentration 1,340 ng/ml and darunavir half-life was 12.2 hr. Tolerability of once-daily darunavir/r 800/100 mg was excellent. Optimally suppressed, treatment-experienced patients can switch safely from a twice-daily PI/r regimen to a once-daily darunavir/r 800/100 mg containing regimen.

Is There a Drug–Drug Interaction Between Darunavir/Ritonavir and Raltegravir?

Is There a Drug–Drug Interaction Between Darunavir/Ritonavir and Raltegravir?

Drug interactions between voriconazole, darunavir/ritonavir and etravirine in an HIV-infected patient with Aspergillus pneumonia

Drug interactions between voriconazole, darunavir/ritonavir and etravirine in an HIV-infected patient with Aspergillus pneumonia

Pharmacokinetic concerns related to the AIDS Clinical Trial Group (ACTG) A5262 trial

Taiwo et al. [1] have recently reported results of the AIDS Clinical Trial Group (ACTG) A5262 trial, specifically designed to investigate a two-drug, reverse transcriptase inhibitor-sparing regimen of darunavir/ritonavir (DRV/r) with raltegravir (RAL) for initial antiretroviral therapy. The proposed regimen met the protocol definition of ‘acceptable virologic efficacy’, but only 60% of participants reached viral load less than 50 copies/ml at week 48 in spite of an unanticipated high incidence of virologic failure and integrase resistance especially in patients with baseline viral load more than 100 000 copies/ml. Taiwo et al. [1] have attempted to find out potential explanations for these unexpected results. Particularly, they have explored the potential contribution of DRV and RAL pharmacokinetics on the study findings. Average DRV and RAL trough concentrations were not significantly different for patients with and without virologic failure. However, sensitivity analyses evidenced a significant role of DRV levels, which were significantly lower in patients with virologic failure compared with those without virologic failure (1042 vs. 1649 ng/ml, P = 0.017). This scenario was further complicated by findings from Cox models, showing that having RAL trough concentrations below the assay detection limit immediately before or at one or more previous visit was also highly significantly associated with increased hazard of virologic failure. So, which conclusions on the value of DRV and RAL therapeutic monitoring can be drawn from this study? We and others [2,3] have previously shown that RAL trough concentrations are associated with large interindividual variability and, most importantly, largely failed to correlate with RAL area under the time–concentration curve (AUC)0-12, taken as the golden standard pharmacokinetic parameter for the quantification of daily drug exposure. Moreover, recent studies have demonstrated that RAL has a resistance time on the integrase/DNA pre-integration complex that exceeds the half-life of the pre-integration complex in the cells [4,5]. Consequently, as the inhibition induced by RAL is functionally irreversible, no association between RAL pharmacokinetics and clinical outcome can be reasonably expected [6]. According to these findings, it is unlikely that RAL trough concentrations can per se directly affect response to therapy of patients enrolled in the ACTG trial. Therefore, other ways in which RAL could indirectly impact on patient outcome should be advocated. A clear indication from the ACTG trial is that, according to sensitivity analyses, DRV concentrations were significantly lower in patients with virologic failure compared with those without virologic failure. Therefore, any factor able to affect DRV pharmacokinetics could theoretically impact on patient outcome. An intriguing hypothesis is that co-administration of RAL may lower plasma concentrations of DRV, as recently documented by Fabbiani et al.[7], ultimately resulting in suboptimal DRV exposure and poor response to combined RAL and DRV therapy. Unfortunately, no matched control patients given DRV/r at comparable dosage without RAL were available from the ACTG trial to compare DRV plasma trough concentrations in patients given or not given RAL. The authors have, however, rejected the hypothesis of a drug–drug interaction because the DRV trough concentrations measured in the ACTG trial were ‘within the range previously reported in an intensive pharmacokinetic study of DRV 800/100 mg daily’ [8]. Taiwo et al. [1] failed, however, to consider an important methodological drawback of their study. Particularly, they based their assumptions on the assessment of trough DRV concentration as the solely pharmacokinetic drug parameter, which is not appropriate for the assessment of drug–drug interactions. Indeed, by performing detailed DRV pharmacokinetic evaluations in 25 HIV-infected patients [9], we have recently shown that co-administration of RAL did not impact on DRV trough levels, but was associated with highly significantly lower DRV AUC0-24 compared with values measured in patients not given RAL (Fig. 1).Fig. 1: Mean (±SD) darunavir (DRV) trough concentration (left panel) and area under the time–concentration curve (AUC)0-24 (right panel) measured in patients given DRV with or without concomitant raltegravir (RAL) administration.According to these findings, a potential pharmacokinetic drug–drug interaction between RAL and DRV ultimately affecting the results of the ACTG A5262 trial cannot be ruled out. This potential interaction should be investigated further and taken into account when DRV with RAL-based HAART regimens are implemented in the setting of HIV. Acknowledgements Both authors have read and approved the text. Conflicts of interest D.C. has received educational/travel grants from Merck Sharp & Dome (MSD) and from Janssen-Cilag. C.G. has received educational grants from Merck Sharp & Dome (MSD), Janssen-Cilag, Bristol Myers Squibb and Abbott.

Desarrollo y validación de un método para la determinación de darunavir en plasma mediante LC-MS/MS

Introduction Darunavir is a latest generation of protease inhibitors (PI) drugs used as a treatment of HIV infection owing to its improved efficacy and its better tolerance among other characteristics. Several studies have demonstrated a correlation between the dose and the effect of darunavir, although a therapeutic range for the drug concentrations has not yet been established. These factors, besides the high inter-individual variability and the adverse effects resulting from drug interactions, reinforce the need for having a sensitive method for monitoring its plasma concentrations in treated patients. Objective Technical validation of a new method for darunavir plasma concentration monitoring by LC/MS/MS. Materials and methods The method validation procedure was based on the recommendations published in the guidelines ICH Topic Q 2B Validation of Analytical Procedures: Methodology ( CPMP/ICH/281/95). Darunavir was extracted from plasma samples by a protein precipitation procedure. The chromatographic separation was achieved with a gradient program (acetonitrile/buffer) on an X-Bridge TM C18 3.5 μm 2.1×100 mm (Waters ®). Analytes quantification is performed by electrospray ionization in positive mode, a Quattro Micro triple quadrupole mass spectrometer. Results Linearity (0.1-10 μg/mL): y = 18.85×-150.4 r 2: 0.997. Precision: Intra-assay CV: 1.07-4.62%. Inter-assay CV: 2.72-4.70%. Accuracy: Intra-assay: 1-9%. Inter-assay: 2-7%. LOD: 0.05 μg/mL, LLOQ: 0.15 μg/mL. Conclusion The developed method based on LC/MS/MS has an adequate sensibility and reproducibility for the determination of plasma concentrations of darunavir in treated patients.

Co-administration of darunavir and a new pharmacokinetic booster: Formulation strategies and evaluation in dogs

Various formulations for combination of the anti-HIV protease inhibitor darunavir (DRV) and TMC41629, a pharmacokinetic booster for DRV, were studied. TMC41629 (a BCS-IV compound) was formulated in capsules, as polyethylene glycol 400 (PEG400) solution, binary or ternary self-microemulsifying drug delivery system (SMEDDS), inclusion complex with hydroxypropyl-beta-cyclodextrin (HPβCD) or polyvinylpyrrolidone-co-vinylacetate 64 (PVP/VA64) extrudate. In addition, tablets were prepared using unmilled or micronized powder and a disintegrant. On co-administration with DRV tablets in dogs, DRV plasma concentration levels were boosted by TMC41629, the PVP/VA64 extrudate achieving the highest DRV levels (2-fold increase). Yet, with extrudate prepared with both compounds, no boosting effect was observed, likely due to transition of DRV from crystalline solvate to amorphous state. Therefore, a co-formulation, combining DRV as crystalline solvate with amorphous TMC41629, was developed. DRV/kappa-carrageenan 80/20% (w/w) beads coated with TMC41629 released at least 80% within 1 h in 0.01 M HCl with 0.5% sodium lauryl sulphate, TMC41629 dissolving faster than DRV. In dogs, the DRV exposure increased 2.7-fold with the TMC41629-coated beads relative to DRV alone, yet remained lower, but less variable, than following co-administration as separate formulations. Coating of TMC41629 on DRV/kappa-carrageenan beads is a suitable technique for co-formulation, whereby TMC41629 can function as a booster of DRV.

The Effect of Different Meal Types on the Pharmacokinetics of Darunavir (TMC114)/Ritonavir in HIV‐Negative Healthy Volunteers

This open-label, randomized, crossover study investigated the bioavailability, short-term safety, and tolerability of darunavir (TMC114) coadministered with low-dose ritonavir under fasted conditions and after different meal types in HIV-negative healthy volunteers. All volunteers received ritonavir 100 mg twice daily on days 1 to 5, with a single darunavir 400-mg tablet given on day 3 (darunavir/rtv). Pharmacokinetic parameters for darunavir and ritonavir were determined under fasted conditions and following a standard breakfast, a high-fat breakfast, a nutritional protein-rich drink, or a croissant with coffee. Administration of darunavir/rtv in a fasting state resulted in a decrease in darunavir C(max) and AUC(last) of approximately 30% compared with administration after a standard meal. No significant differences in darunavir plasma concentrations were observed between different fed states. Darunavir/rtv should therefore be administered with food, but exposure to darunavir is not affected by the type of meal.