Original article Bioequivalence of a darunavir/cobicistat fixed-dose combination tablet versus single agents and food effect in healthy volunteers

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1 Antiviral Therapy 2014; 19: (doi: /IMP2814) Original article Bioequivalence of a darunavir/cobicistat fixed-dose combination tablet versus single agents and food effect in healthy volunteers Thomas N Kakuda 1 *, Tom Van De Casteele 2, Romana Petrovic 2, Mark Neujens 3, Hiba Salih 3, Magda Opsomer 2, Richard MW Hoetelmans 2 1 Janssen Research & Development, LLC, Titusville, NJ, USA 2 Janssen Infectious Diseases BVBA, Beerse, Belgium 3 CPU Janssen Pharmaceutica NV, Antwerp, Belgium *Corresponding author tkakuda@its.jnj.com Background: Darunavir requires pharmacokinetic enhancement to increase its bioavailability. Cobicistat is potentially an alternative pharmacokinetic booster to ritonavir. Bioequivalence of a darunavir/cobicistat fixed-dose combination (FDC) versus darunavir and cobicistat co-administered as single agents and the effect of a high-fat meal on the pharmacokinetics of the FDC were evaluated. Methods: In this Phase I, open-label, randomized, three-panel, crossover study (NCT ), healthy volunteers received a single dose of darunavir (800 mg) with cobicistat (150 mg) as either an FDC or as single agents co-administered under fasted (panel 1, n=74) or fed (breakfast, panel 2, n=40) conditions, or as the FDC under fasted versus fed (high-fat breakfast) conditions (panel 3, n=19), with a 7 day washout period between treatments. Pharmacokinetic profiles, safety and tolerability were assessed. Results: 90% confidence intervals of the least square mean ratios for darunavir and cobicistat maximum plasma concentration and area under the plasma concentration time curve (AUC) were all within 80.00% and % in panels 1 and 2. Administration of the FDC with a highfat breakfast significantly increased darunavir maximum plasma concentration 2.27-fold and AUC fold, whereas cobicistat pharmacokinetics were unaffected. No volunteers discontinued due to adverse events (AEs). All AEs were grade 1 or 2. Overall, 27 (20%) and 26 (20%) volunteers had 1 AE at least possibly related to darunavir and cobicistat, respectively. Conclusions: Bioequivalence of the darunavir/cobicistat 800/150-mg FDC was demonstrated versus darunavir and cobicistat co-administered as single agents under fasted or fed conditions. Food increased darunavir exposure, therefore, darunavir/cobicistat should be administered with food. Introduction Many treatment guidelines for HIV-1 infection recommend protease inhibitors (PIs), usually boosted with low-dose ritonavir, in combination with other antiretrovirals for treatment-naive and -experienced patients. Ritonavir-boosted darunavir, a PI, is one of the preferred treatment options in current guidelines [1 4]. Ritonavir has intrinsic antiviral activity against the HIV-1 virus and was originally approved for use as a PI at a dose of 600 mg twice daily. However, ritonavir is now almost exclusively used as a pharmacokinetic enhancer at a low dose (100 mg once or twice daily). Ritonavir is a potent inhibitor of cytochrome P450 (CYP) 3A, thereby increasing the oral bioavailability of CYP3A substrates, including most HIV-1 PIs [5]. Indeed, co-administration of low-dose ritonavir increased darunavir plasma concentrations 11-fold versus darunavir alone [6]. Low-dose ritonavir is associated with adverse events (AEs), with the most frequently reported being gastrointestinal disorders and (when used as the liquid formulation) taste disturbance [5]. Furthermore, hyperlipidaemia has also been associated with lowdose ritonavir [7]. Ritonavir is an inducer of several CYP isozymes (CYP1A2, CYP2B6, CYP2C9 and CYP2C19) and glucuronosyl transferase, and is an inhibitor of CYP2D6 and P-glycoprotein [8]. Thus, 2014 International Medical Press (print) (online) 597

2 TN Kakuda et al. clinically significant drug drug interactions can occur with ritonavir. A pharmacokinetic enhancer with reduced tolerability issues compared with ritonavir would be an important addition to antiretroviral combination therapy. Cobicistat (GS-9350), a structural analogue of ritonavir, is a potent CYP3A inhibitor [9,10]. Cobicistat has not demonstrated in vitro antiviral activity [10] and does not induce CYP isozymes or efflux transporter proteins [9,10]. Like ritonavir, cobicistat inhibits CYP2D6 and P-glycoprotein. Cobicistat also inhibits the organic anion transport protein (OATP) 1B1 and OATP1B3, breast cancer resistance protein (BCRP), and multidrug and toxin extrusion protein 1 (MATE-1) [9,11 13]. Due to its chemical stability, cobicistat can be co formulated into fixed-dose combinations (FDCs) [12]. The availability of an FDC of an HIV-1 PI and cobicistat suitable for once-daily dosing would reduce pill burden, thereby potentially improving adherence [14 18]. Several Phase I studies have shown that cobicistat is an effective pharmacokinetic enhancer and may be a suitable alternative to ritonavir. For example, in healthy volunteers, elvitegravir pharmacokinetic parameters following administration of an FDC consisting of elvitegravir, emtricitabine, tenofovir disoproxil fumarate and cobicistat were similar to those of ritonavir-boosted elvitegravir [19]. Atazanavir plasma concentrations were comparable following co-administration of atazanavir/ritonavir (300/100 mg) versus atazanavir/cobicistat (300/150 mg) [20]. Furthermore, comparable efficacy and safety of cobicistat versus ritonavir as pharmacokinetic enhancers of atazanavir combined with emtricitabine/tenofovir disoproxil fumarate has been demonstrated in treatment-naive, HIV-1-infected patients [21,22]. Darunavir pharmacokinetic parameters following once-daily darunavir (800 mg) co-administered with cobicistat (150 mg), either as single agents [23] or as two candidate FDC formulations (G003 and G004) [24] were similar to those of once-daily darunavir/ritonavir (800/100 mg), except for lower darunavir plasma concentrations at the end of the dosing interval with darunavir/cobicistat [23,24]. In the second study, both candidate FDC formulations were suitable for further development and G004 was selected. The final FDC formulation for commercialization, G006, is G004 with a non-functional pink colour coating (G004 was a white tablet). The primary objective of the present Phase I study was to evaluate the single-dose pharmacokinetics and bioequivalence of darunavir administered as an FDC with cobicistat (G006) versus single agents, under fasted or fed conditions. The secondary objectives were to determine cobicistat pharmacokinetic parameters, the effect of a high-fat meal on darunavir and cobicistat pharmacokinetics (when administered as the FDC), and the short-term tolerability of darunavir/cobicistat administration. Methods Sample size In a previous single 800-mg darunavir dose pharmacokinetic study, the within-volunteer standard deviations (logarithmic scale) for darunavir area under the plasma concentration time curve (AUC) were estimated to be 0.34 (fasted conditions) and 0.24 (fed conditions) [25]. Using a two one-sided t-test at a=0.05 nominal level, the number of volunteers required to demonstrate bioequivalence of the darunavir/cobicistat FDC versus single agents with 90% power (when the true difference between treatments within a panel is 5%) was 70 (fasted conditions, panel 1) and 36 (fed conditions, panel 2). No formal sample size estimation was conducted for panel 3 (FDC under fasted and fed conditions). A minimum of 16 volunteers was considered sufficient to assess the effect of a high-fat breakfast on the FDC. This sample size would yield a precision of the geometric mean ratio for darunavir AUC of 24%. Study population Key eligibility criteria included: males or females aged years old, with a body mass index kg/m 2. Women were required to be postmenopausal for 2 years, or surgically sterile, or using highly effective birth control. All volunteers had to be healthy based on physical examination, medical history, vital signs, electrocardiogram results and clinical laboratory tests (serum chemistry, haematology and urinalysis). Key exclusion criteria were recent/current substance abuse, significant currently active disease and use of disallowed therapies (including over-the-counter products, herbal preparations and dietary supplements). The study protocol was reviewed by an Independent Ethics Committee (Ethical Committee, University Hospital, Antwerp, Belgium). All volunteers provided written, informed consent. The study was conducted in accordance with the Declaration of Helsinki and Good Clinical Practice. Study design This study (TMC114IFD1003; NCT ) was a Phase I, open-label, randomized, three-panel, singlecentre, crossover study conducted between May and August Three panels of volunteers were randomized (on day 1 of the first treatment phase of the study), using a pre-defined randomization list created using permuted blocks, to receive two treatments with a washout period of 7 days between each treatment session. The treatment sequences were panel 1: International Medical Press

3 Darunavir/cobicistat combination tablet bioequivalence vs single agents AB or BA; panel 2: CD or DC; and panel 3: EF or FE. The six treatments were: darunavir and cobicistat as single agents without (A) or with food (standardized breakfast; C); the darunavir/cobicistat FDC without (B and E) or with food (standardized breakfast D and high-fat breakfast F). Study treatment Volunteers were screened up to 21 days prior to study start and were admitted to the study unit on day -1 of each treatment phase. Study drugs were administered on day 1 and the volunteers were discharged from the unit on day 4 of each phase. Each treatment consisted of a single oral dose of darunavir (800 mg) and cobicistat (150 mg). In panel 1 (n=74, fasting), treatment A (reference) was single agents (two 400-mg darunavir tablets [commercial formulation F030] with one 150-mg cobicistat tablet) and treatment B (test) was the FDC (formulation G006). The same treatments were administered in panel 2 (n=40), either as single agents (treatment C, reference) or the FDC (treatment D, test), but were administered under fed conditions, that is, a standardized breakfast. In panel 3 (n=19), all volunteers were given the FDC under fasted (treatment E, reference) and fed (high-fat breakfast; treatment F, test) conditions. The standardized breakfast (533 kcal; 21 g fat) consisted of (or its equivalent) four slices of bread, two slices of ham and/or cheese, butter, jelly and two cups (up to 480 ml) of decaffeinated coffee or tea with milk and/or sugar, if required. The high-fat breakfast (928 kcal; 56 g fat) consisted of (or its equivalent) two scrambled eggs, 114 g (4 oz) hashed brown potatoes, two strips of bacon, two slices of bread, butter, jelly and 240 ml (8 oz) of whole milk. These meals were consumed within 30 min and the study drugs were taken within 30 min of starting the breakfast. Pharmacokinetic assessments Venous blood samples were collected predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 9, 12, 16, 20, 24, 36, 48, 60 and 72 h after darunavir/cobicistat intake. Plasma concentrations of darunavir [26] and cobicistat [10] were measured using validated liquid chromatographic mass spectrometry/mass spectrometry methods, with lower limits of quantification of 5.00 ng/ml and 2.00 ng/ml, respectively. Plasma concentration time curves were plotted, and descriptive statistics were calculated for darunavir and cobicistat pharmacokinetic parameters (WinNonlin Professional version 4.1, Pharsight, Mountain View, CA, USA). Key pharmacokinetic parameters included maximum plasma concentration ( ), time to (T max ), terminal elimination half-life (T 1/2 ), AUC from time of administration up to the last time point with a measurable concentration post-dose ( ) calculated by linear linear trapezoidal summation and extrapolated to infinity ( ) using the following equation: = +C last /l where C last is the last measurable plasma concentration and l is the elimination rate constant (l=0.693/t 1/2 ). For each treatment group, the least square (LS) means of for darunavir and cobicistat were estimated with a linear mixed-effects model, controlling for treatment, session and sequence as fixed effects, and subject as a random effect (SAS version 9.3; SAS Institute, Cary, NC, USA). Bioequivalence was established if the 90% confidence intervals (CIs) of the LS means ratio for the test versus reference were within the limits of %. Safety and tolerability assessments AEs, including severity and causality, were assessed continuously throughout the study. Clinical chemistry, haematology, urinalysis and vital signs were evaluated during screening, on days 1 and 4 of each treatment phase, and during the final follow-up (7 10 days after the last intake of study drugs). Physical examinations of the volunteers took place during screening, on day 4 of each phase and during follow-up. AEs were coded based on the Medical Dictionary for Regulatory Activities (version 15.0). Laboratory data were assessed using the National Institutes of Allergy and Infectious Diseases Division of AIDS toxicity scale [27]. Results Disposition and baseline characteristics Overall, 333 volunteers were screened and 200 were excluded (125 did not meet the entry criteria; 39 withdrew consent; 36 were reserves). Of the 133 randomized and treated volunteers (panel 1, n=74; panel 2, n=40; panel 3, n=19), 3 discontinued: 1 for a protocol violation (panel 1) and 2 withdrew consent (both in panel 2). Thus, 130 volunteers completed the study. The baseline characteristics were generally well balanced across the three panels. For panels 1, 2 and 3, respectively, the median (range) age was 46.0 (19 60), 43.0 (19 60) and 46.0 (22 59) years. The median (range) body mass index was 25.1 (19 30), 25.2 (20 30) and 25.3 (19 30) kg/m 2, respectively. Just over half of the volunteers were male (54.1%, 57.5% and 57.9%, respectively), and almost all were White (98.6%, 100% and 94.7%, respectively). Most volunteers were non-smokers (93.2%, 92.5% and 89.5%, respectively). Pharmacokinetics of FDC versus single agents Darunavir pharmacokinetics Darunavir plasma concentration time curves, in the presence of cobicistat, following administration of Antiviral Therapy

4 TN Kakuda et al. the FDC (800/150 mg) were similar to those after ingestion of single agents, under fed or fasted conditions (Figure 1A). Within a panel, comparable values for darunavir median T max and mean T 1/2 were observed between the FDC and single agents (Table 1). For both fasted and fed conditions, bioequivalence of the darunavir/ cobicistat 800/150-mg FDC versus single agents was demonstrated as the 90% CIs of the LS means ratio for of darunavir were all within 80.00% and % (Table 1). Cobicistat pharmacokinetics Mean cobicistat plasma concentrations over time, in the presence of darunavir, when given as the single FDC (800 mg darunavir/150 mg cobicistat) were comparable to those after administration of single agents, regardless of intake being under fed or fasted conditions (Figure 1B). Comparable values for cobicistat mean T 1/2 were observed for the FDC and single agents, for both fed and fasted conditions (Table 2). For cobicistat,, the 90% CIs of the LS means ratio, under both fasted or fed conditions, were all within 80.00% and %, demonstrating the bioequivalence of the FDC versus single agents (Table 2). Effect of food Darunavir pharmacokinetics Administration of the 800/150-mg darunavir/cobicistat FDC with food (high-fat breakfast) resulted in higher darunavir plasma concentrations compared with fasted conditions (Figure 2A). Darunavir and were significantly increased by 2.27-, and 1.70-fold, respectively, for fed versus fasted conditions (Table 3). The lower bound 90% CIs of the LS mean ratios for these parameters were all above 125%. The median T max for darunavir was prolonged after administration of the FDC tablet with a high-fat breakfast compared with fasted conditions, was similar between these states (Table 3). Consistent with these findings, in panels 1 and 2, for both the FDC and single agents, darunavir/cobicistat administration with food (standardized breakfast) resulted in higher darunavir plasma concentrations versus fasting conditions (Figure 1A). Cobicistat pharmacokinetics A high-fat breakfast delayed the T max of cobicistat compared with fasted conditions (Figure 2B; Table 3). Cobicistat T 1/2 was comparable between fed and fasted conditions (Table 3). The 90% CIs of the LS mean ratios for cobicistat were all within 80.00% and % following administration of the FDC 800/150-mg darunavir/ cobicistat with a high-fat breakfast versus fasted conditions (Table 3). Again, consistent with these results in for both the FDC and single agents in panels 1 and 2, darunavir/cobicistat administration with food (standardized breakfast) slightly delayed T max compared with fasting conditions (Figure 1B; Table 2). Safety and tolerability No volunteer discontinued the study due to AEs. Overall, 64/133 (48%) volunteers had 1 AE during treatment with darunavir/cobicistat. No relevant differences in the incidence of AEs were observed between administration of the FDC compared with single agents, or between fed and fasted conditions. Under fasting conditions, 32% (23/73; single agents), 41% (30/74; FDC) and 26% (5/19; FDC) volunteers had 1 AE. For fed conditions, the proportion of volunteers with 1 AE was 34% (13/38; single agents, standardized breakfast), 40% (16/40; FDC, standardized breakfast) and 32% (6/19; FDC, high-fat breakfast). All AEs were grade 1 (56 [42%] volunteers) or 2 (8 [6%] volunteers). The most common AEs (in 5% of volunteers during any treatment phase) were headache (40/133 [30%]), muscle spasms (12/133 [9%]), diarrhoea (11/133 [8%]) and nausea (6/133 [5%]). Overall, 27/133 (20%) and 26/133 (20%) volunteers had AEs considered to be at least possibly related to darunavir or cobicistat, respectively. The most frequent graded laboratory abnormalities were increased cholesterol concentrations (total cholesterol, 55 [41%] volunteers; low-density lipoprotein cholesterol, 35 [26%] volunteers), which were mainly grade 1 in severity. No consistent or clinically relevant changes in blood chemistry, haematology, urinalysis or vital signs were observed. No laboratory abnormalities were reported as AEs. Discussion The present study demonstrated the bioequivalence of the 800/150-mg FDC (formulation G006) of darunavir/ cobicistat versus single agents, following administration under both fasted and fed conditions. Compared with fasting conditions, food increased exposure to darunavir, but had no effect on cobicistat exposure. A single dose of darunavir/cobicistat administered as the FDC or as single agents was well tolerated. Plasma concentrations of most HIV PIs, including darunavir, sufficient for antiviral activity are achieved by pharmacokinetic enhancement [1 6,28]. Two previous studies in healthy volunteers have directly compared the effects of the pharmacokinetic enhancers ritonavir and cobicistat on steady-state International Medical Press

5 Darunavir/cobicistat combination tablet bioequivalence vs single agents Figure 1. Darunavir and cobicistat plasma concentration time curves following administration of a single dose of 800 mg darunavir with 150 mg cobicistat as either an FDC or as single agents, under fasted or fed conditions A Mean plasma concentration of darunavir, ng/ml (±SD) 8,000 6,000 4,000 2,000 Single agents - fasted (n=72) FDC - fasted (n=74) Single agents - fed (n=38) FDC - fed (n=40) B Mean plasma concentration of cobicistat, ng/ml (±SD) 0 1, Time, h Single agents - fasted (n=72) FDC - fasted (n=74) Single agents - fed (n=38) FDC - fed (n=40) Time, h (A) Darunavir and (B) cobicistat plasma concentration time curves following administration of a single dose of 800 mg darunavir with 150 mg cobicistat as either a fixed-dose combination (FDC) or as single agents, under fasted (panel 1) or fed (standardized breakfast; panel 2) conditions. Antiviral Therapy

6 TN Kakuda et al. Table 1. Darunavir pharmacokinetic parameters and statistical analyses following administration of single dose of 800 mg darunavir with 150 mg cobicistat as either an FDC or as single agents, under fasted or fed (standardized breakfast) conditions Panel 1: fasted conditions Panel 2: fed conditions Pharmacokinetic parameter Single agents (reference; n=72 b ) FDC (test; n=74 b ) Single agents (reference; n=38 c ) FDC (test; n=40 d ) Mean (sd) a, ng/ml 3,129 (933) 3,087 (927) 6,979 (1,201) 6,773 (1,343) T max, h 3.0 ( ) 3.0 ( ) 4.0 ( ) 4.0 ( ), ng h/ml 47,326 (18,314) 46,329 (18,476) 81,483 (27,540) 78,942 (26,709), ng h/ml 47,668 (18,689) 46,291 (18,781) 79,836 (26,913) 78,811 (27,304) T 1/2, h 7.2 (3.3) 7.6 (3.5) 5.5 (1.6) 6.7 (3.4) LS means ratio (test/reference; 90% CI) 0.99 (0.94, 1.04) 0.97 (0.93, 1.01) 0.96 (0.91, 1.02) 0.98 (0.93, 1.03) 0.96 (0.90, 1.02) 0.98 (0.93, 1.03) a Except T max = median (range). b n=66 for. c n=35 for. d n=37 for. AUC 0-, area under the concentration time curve from time of administration and extrapolated to infinity; AUC 0-last, area under the concentration time curve from time of administration up to the last time point with a measurable concentration post dose;, maximum plasma concentration; CI, confidence interval; FDC, fixed-dose combination; LS, least square; T 1/2, terminal elimination half-life; T max, time to. Table 2. Cobicistat pharmacokinetic parameters and statistical analyses following administration of single dose of 800 mg darunavir with 150 mg cobicistat as either the FDC or as single agents, under fasted or fed (standardized breakfast) conditions Panel 1: fasted conditions Panel 2: fed conditions Pharmacokinetic parameter Single agents (reference; n=72 b ) FDC (test; n=73 c ) Single agents (reference; n=38) FDC (test; n=40) Mean (sd) a, ng/ml 664 (301) 697 (339) 823 (208) 819 (221) T max, h 2.5 ( ) 2.0 ( ) 4.0 ( ) 4.0 ( ), ng h/ml 4,962 (2,493) 5,219 (3,051) 6,401 (2,745) 6,285 (2,735), ng h/ml 5,106 (2,474) 5,448 (3,005) 6,511 (2,784) 6,388 (2,779) T 1/2, h 4.0 (0.9) 3.9 (0.8) 3.9 (0.9) 3.8 (0.8) LS means ratio (test/reference; 90% CI) 1.03 (0.94, 1.13) 0.98 (0.94, 1.02) 1.01 (0.92, 1.12) 0.98 (0.95, 1.01) 1.04 (0.95, 1.15) 0.98 (0.95, 1.01) a Except T max = median (range); b n=71 for ; c n=71 for and n=72 for T 1/2. AUC 0-, area under the concentration time curve from time of administration and extrapolated to infinity; AUC 0-last, area under the concentration time curve from time of administration up to the last time point with a measurable concentration post dose;, maximum plasma concentration; CI, confidence interval; FDC, fixed-dose combination; LS, least square; T 1/2, terminal elimination halflife; T max, time to. darunavir pharmacokinetics in once-daily dosing regimens [23,24]. Using single agents under fed conditions, the first study demonstrated that and AUC (0-tau) of darunavir were comparable with cobicistat (800/150 mg once daily) and ritonavir (800/100 mg once daily) co-administration [23]. The second study examining two darunavir/cobicistat FDCs (G003 and G004; both 800/150 mg once daily) versus darunavir/ritonavir (800/100 mg once daily) as single agents showed both co-formulations were comparable to single agents darunavir/ritonavir based on the LS means ratio for and AUC (0-24h) [24]. In both studies, darunavir C min was modestly lower with cobicistat as the pharmacoenhancer rather than ritonavir. However, this effect is unlikely to be clinically relevant since no significant relationship between darunavir C min and virological response has been demonstrated [29,30]. Indeed, modelling suggests that a reduction of up to 50% in darunavir trough levels would not reduce virological activity [31]. The present study was conducted to extend the previous healthy volunteer studies by assessing the bioequivalence of the G006 darunavir/cobicistat FDC versus single agents. Our results demonstrated that the rate (T max ) and extent ( ) of absorption and total systemic exposure ( ) to both International Medical Press

7 Darunavir/cobicistat combination tablet bioequivalence vs single agents Figure 2. Darunavir and cobicistat plasma concentration-time curves following administration of single dose of 800 mg darunavir/150 mg cobicistat as the FDC under fasted and fed conditions A Mean plasma concentration of darunavir, ng/ml (±SD) 8,000 6,000 4,000 2,000 FDC - fasted (n=18) FDC - fed (n=18) B Mean plasma concentration of cobicistat, ng/ml (±SD) 0 1, Time, h FDC - fasted (n=18) FDC - fed (n=18) Time, h (A) Darunavir and (B) cobicistat plasma concentration time curves following administration of single dose of 800 mg darunavir/150 mg cobicistat as the fixed-dose combination (FDC) under fasted and fed (high-fat breakfast) conditions (panel 3). Antiviral Therapy

8 TN Kakuda et al. Table 3. Darunavir and cobicistat pharmacokinetic parameters and statistical analyses following administration of single dose of 800 mg darunavir/150 mg cobicistat as the FDC under fasted and fed (high-fat breakfast) conditions (panel 3) Darunavir Cobicistat Pharmacokinetic parameter Fasted (reference; n=18 b ) Fed (test; n=18 c ) Fasted (reference; n=18) Fed (test; n=18 d ) Mean (sd) a, ng/ml 3,173 (859) 7,053 (1,057) 741 (222) 769 (174) T max, h 3.0 ( ) 4.5 ( ) 2.0 ( ) 5.0 ( ), ng h/ml 47,356 (17,723) 75,258 (21,632) 5,459 (1,959) 5,491 (1,425), ng h/ml 43,985 (13,548) 76,165 (22,090) 5,532 (1,967) 5,526 (1,478) T 1/2, h 6.8 (3.1) 6.6 (3.2) 3.9 (0.7) 3.9 (0.7) LS means ratio (test/reference; 90% CI) 2.27 (2.06, 2.51) 1.06 (0.98, 1.14) 1.63 (1.45, 1.84) 1.04 (0.96, 1.12) 1.70 (1.49, 1.95) 1.04 (0.96, 1.13) a Except T max = median (range); b n=16 for ; c n=17 for ; d n=17 for. AUC 0-, area under the concentration time curve from time of administration and extrapolated to infinity; AUC 0-last, area under the concentration time curve from time of administration up to the last time point with a measurable concentration post dose;, maximum plasma concentration; CI, confidence interval; FDC, fixed-dose combination; LS, least square; T 1/2, terminal elimination half-life; T max, time to. darunavir and cobicistat were comparable between the FDC and single agents, under fasted and fed conditions. For both darunavir and cobicistat, bioequivalence of the FDC with single agents was demonstrated as the 90% CIs for were all within 80.00% and %. Our findings are clinically noteworthy since the availability of an FDC for darunavir/cobicistat would reduce the pill burden for HIV-1-infected patients being treated with ritonavir-boosted darunavir. Pill burden has been shown to have a major impact on adherence [1,14,15], and the latter is a key factor for the long-term success of antiretroviral therapy [1]. Furthermore, FDCs, by reducing pill burden, have a role in improving treatment adherence [16 18,32]. Further to this several ongoing clinical trials are evaluating the safety and efficacy of cobicistat-boosted darunavir in combination with other antiretroviral agents in HIV-1-infected adults (Phase II: NCT ; Phase III: NCT and NCT ). A food effect was observed in the present study as, in the presence of cobicistat, darunavir pharmacokinetic parameters, that is,, for panel 2 (fed conditions standardized breakfast) were all higher compared with those in panel 1 (fasted conditions) following administration of the FDC and the single agents. Furthermore, for the FDC, administration with a high-fat breakfast significantly increased darunavir versus fasted conditions. These findings with darunavir co-administered with cobicistat are consistent with the food effect reported for darunavir/ritonavir in healthy volunteers [33]. In the latter study, the type of meal did not affect darunavir pharmacokinetic parameters and, compared with fasted conditions, darunavir was increased by fold and by fold [33] by the presence of food. For cobicistat, a small food effect was seen in the present study as cobicistat and were slightly higher with a standardized breakfast (panel 2) versus fasted conditions (panel 1). However, with the FDC, there were no significant differences in cobicistat pharmacokinetic parameters between fasted and fed (high-fat breakfast) conditions. Overall, these results demonstrate that the darunavir/cobicistat FDC should be taken with food. Although our study only investigated a single oral dose of darunavir/cobicistat, the FDC and single agents were generally well tolerated and no new safety issues were identified. The results are consistent with the AE profile reported for multiple dosing with 800/150 mg once-daily darunavir/cobicistat in healthy volunteers [23,24]. Moreover, the AEs considered at least possibly related to darunavir in the present study were consistent with those reported with once-daily darunavir/ritonavir (800/100 mg) in healthy volunteers [33] and in HIV-1-infected patients [28,34,35]. In conclusion, this healthy volunteer study demonstrated that the FDC of darunavir/cobicistat (800/150 mg; formulation G006) was bioequivalent to administration of single agents, under fasted and fed conditions. Presence of food increased exposure to darunavir and had no effect on cobicistat pharmacokinetics. Darunavir/cobicistat should therefore be administered with food. A single dose of darunavir/ cobicistat as the FDC or as single agents was well tolerated. These data support the further development of a darunavir/cobicistat FDC International Medical Press

9 Darunavir/cobicistat combination tablet bioequivalence vs single agents Acknowledgements The authors are grateful to the study volunteers for their participation, and thank the trial centre staff from the Janssen Clinical Pharmacology Unit, Merksem, Belgium and the Janssen Research & Development team members for their input, in particular Eric Wong. The authors received medical writing support and assistance in co-ordinating and collating author contributions from Jackie Phillipson of Gardiner-Caldwell Communications Ltd, Macclesfield, UK, which was funded by Janssen. Data were previously presented at the 14th International Workshop on Clinical Pharmacology of HIV Therapy (IWCPHIV; Amsterdam, the Netherlands, April, Poster P_10). Disclosure statement This trial was sponsored by Janssen. TNK, TVDC, MN, HS, MO and RMWH are full-time employees of Janssen. RP is a full-time consultant to Janssen. References 1. DHHS guidelines: Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Department of Health and Human Services (Updated May Accessed 22 September 2014.) Available from lvguidelines/adultandadolescentgl.pdf 2. EACS. European AIDS Clinical Society Guidelines. (Updated June Accesssed 22 September 2014.) Available from Portals/0/140601_EACS%20EN7.02.pdf 3. Thompson MA, Aberg JA, Hoy JF, et al. Antiretroviral treatment of adult HIV infection, 2012 recommendations of the International Antiviral Society-USA Panel. JAMA 2012; 308: Williams I, Churchill D, Anderson J, et al. British HIV Association guidelines for the treatment of HIV-1-positive adults with antiretroviral therapy HIV Med 2012; 13 Suppl 2: Hull MW, Montaner JS. Ritonavir-boosted protease inhibitors in HIV therapy. Ann Med 2011; 43: Vermeir M, Lachau-Durand S, Mannens G, et al. Absorption, metabolism, and excretion of darunavir, a new protease inhibitor, administered alone and with low-dose ritonavir in healthy subjects. Drug Metab Dispos 2009; 37: Samaras K, Richardson R, Carr A. Postprandial lipid effects of low-dose ritonavir vs. raltegravir in HIV-uninfected patients. AIDS 2010; 24: Foisy MM, Yakiwchuk EM, Hughes CA. Induction effects of ritonavir: implications for drug interactions. Ann Pharmacother 2008; 42: Xu L, Liu H, Murray B, et al. Cobicistat (GS-9350): a potent and selective inhibitor of human CYP 3A as a novel pharmacoenhancer. ACS Med Chem Lett 2010; 1: Mathias AA, German P, Murray BP, et al. Pharmacokinetics and pharmacodynamics of GS-9350: a novel pharmacokinetic enhancer without anti-hiv activity. Clin Pharmacol Ther 2010; 87: Lepist EI, Phan TK, Roy A, et al. Cobicistat boosts the intestinal absorption of transport substrates, including HIV protease inhibitors and GS-7340, in vitro. Antimicrob Agents Chemother 2012; 56: Shah BM, Schafer JJ, Priano J, Squires KE. Cobicistat: a new boost for the treatment of human immunodeficiency virus infection. Pharmacotherapy 2013; 33: Lepist El, Zhang X, Hao J, et al. Contribution of the organic anion transporter OAT2 to the renal active tubular secretion of creatinine and mechanism for serum creatinine elevations caused by cobicistat. Kidney Int 2014; 86: Buscher A, Harman C, Kallen MA, Giordano TP. Impact of antiretroviral dosing frequency and pill burden on adherence among newly diagnosed, antiretroviral-naive HIV patients. Int J STD AIDS 2012; 23: Juday T, Gupta S, Grimm K, Wagner S, Kim E. Factors associated with complete adherence to HIV combination antiretroviral therapy. HIV Clin Trials 2011; 12: Sterrantino G, Santoro L, Bartolozzi D, Trotta M, Zaccarelli M. Self-reported adherence supports patient preference for the single tablet regimen (STR) in the current cart era. Patient Prefer Adherence 2012; 6: Kauf TL, Davis KL, Earnshaw SR, Davis EA. Spillover adherence effects of fixed-dose combination HIV therapy. Patient Prefer Adherence 2012; 6: Bangalore S, Kamalakkannan G, Parkar S, Messerli FH. Fixed dose combinations improve medication compliance: a meta-analysis. Am J Med 2007; 120: German P, Warren D, West S, Hui J, Kearney BP. Pharmacokinetics and bioavailability of an integrase and novel pharmacoenhancer-containing single-tablet fixed-dose combination regimen for the treatment of HIV. J Acquir Immune Defic Syndr 2010; 55: Ramanathan S, Warren D, Wei L, Kearney BP. Pharmacokinetic boosting of atazanavir with the pharmacoenhancer GS-9350 versus ritonavir. 49th Interscience Conference on Antimicrobial Agents and Chemotherapy September 2009, San Francisco, CA, USA. Abstract A Elion R, Cohen C, Gathe J, et al. Phase 2 study of cobicistat versus ritonavir each with once-daily atazanavir and fixeddose emtricitabine/tenofovir DF in the initial treatment of HIV infection. AIDS 2011; 25: Gallant JE, Koenig E, Andrade-Villanueva J, et al. Cobicistat versus ritonavir as a pharmacoenhancer of atazanavir plus emtricitabine/tenofovir disoproxil fumarate in treatmentnaïve HIV type 1-infected patients: week 48 results. J Infect Dis 2013; 208: Mathias A, Liu HC, Warren D, Sekar V, Kearney BP. Relative bioavailability and pharmacokinetics of darunavir when boosted with the pharmacoenhancer GS-9350 versus RTV. 11th International Workshop on Clinical Pharmacology of HIV Therapy. 7 9 April 2010, Sorrento, Italy. Abstract Kakuda TN, Opsomer M, Timmers M, et al. Pharmacokinetics of darunavir in fixed-dose combination with cobicistat compared with coadministration of darunavir and ritonavir as single agents in healthy volunteers. J Clin Pharmacol 2014; 54: Kakuda TN, Leopold L, Timmers M, et al. Bioavailability and bioequivalence of a darunavir 800-mg tablet formulation compared with the 400-mg tablet formulation. Int J Clin Pharmacol Ther 2014; 52: Schöller-Gyüre M, Kakuda RN, Sekar V, et al. Pharmacokinetics of darunavir/ritonavir and TMC125 alone and coadministered in HIV-negative volunteers. Antivir Ther 2007; 12: DAIDS Table for Grading the Severity of Adult and Pediatric Adverse Events. Version 1.0. December 2004 (Updated August Accessed 19 June 2013.) Available from safetyandpharmacovigilance/table_for_grading_severity_ of_adult_pediatric_adverse_events.pdf Antiviral Therapy

10 TN Kakuda et al. 28. Boffito M, Miralles D, Hill A. Pharmacokinetics, efficacy, and safety of darunavir/ritonavir 800/100 mg once-daily in treatment-naïve and -experienced patients. HIV Clin Trials 2008; 9: Sekar V, Vanden Abeele C, Van Baelen B, et al. Pharmacokinetic-pharmacodynamic analyses of once-daily darunavir-ritonavir in the ARTEMIS study. 15th Conference on Retroviruses and Opportunistic Infections. 3 6 February 2008, Boston, MA, USA. Abstract Sekar V, De La Rosa G, Van de Casteele T, et al. Pharmacokinetic (PK) and pharmacodynamic analyses of once- and twice-daily darunavir/ritonavir (DRV/r) in the ODIN trial. 10th International Conference on Drug Therapy in HIV Infection November 2010, Glasgow, UK. Abstract P Kakuda T, Brochot A, Tomaka F, et al. Generalized additive model analysis of the relationship between darunavir pharmacokinetics and pharmacodynamics following once daily darunavir/ritonavir 800/100mg treatment in the Phase III trials ARTEMIS and ODIN. 11th International Congress on Drug Therapy in HIV Infection November 2012, Glasgow, UK. Abstract P072. Accepted 6 May 2014; published online 25 June Connor J, Rafter N, Rodgers A. Do fixed-dose combination pills or unit-of-use packaging improve adherence? A systematic review. Bull World Health Organ 2004; 82: Sekar V, Kestens D, Spinosa-Guzman S, et al. The effect of different meal types on the pharmacokinetic of darunavir (TMC114)/ritonavir in HIV-negative healthy volunteers. J Clin Pharmacol 2007; 47: Cahn P, Fourie J, Grinzstein B, et al. Week 48 analysis of once-daily vs. twice-daily darunavir/ritonavir in treatment-experienced HIV-1-infected patients. AIDS 2011; 25: Orkin C, DeJesus E, Khanlou H, et al. Final 192-week efficacy and safety of once-daily darunavir/ritonavir compared with lopinavir/ritonavir in HIV-1-infected treatment-naive patients in the ARTEMIS trial. HIV Med 2013; 14: International Medical Press