Parameterization of Physiologically Based Biopharmaceutics Models: Workshop Summary Report.

This Article shares the proceedings from the August 29th, 2023 (day 1) workshop "Physiologically Based Biopharmaceutics Modeling (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives". The focus of the day was on model parametrization; regulatory authorities from Canada, the USA, Sweden, Belgium, and Norway presented their views on PBBM case studies submitted by industry members of the IQ consortium. The presentations shared key questions raised by regulators during the mock exercise, regarding the PBBM input parameters and their justification. These presentations also shed light on the regulatory assessment processes, content, and format requirements for future PBBM regulatory submissions. In addition, the day 1 breakout presentations and discussions gave the opportunity to share best practices around key questions faced by scientists when parametrizing PBBMs. Key questions included measurement and integration of drug substance solubility for crystalline vs amorphous drugs; impact of excipients on apparent drug solubility/supersaturation; modeling of acid-base reactions at the surface of the dissolving drug; choice of dissolution methods according to the formulation and drug properties with a view to predict the in vivo performance; mechanistic modeling of in vitro product dissolution data to predict in vivo dissolution for various patient populations/species; best practices for characterization of drug precipitation from simple or complex formulations and integration of the data in PBBM; incorporation of drug permeability into PBBM for various routes of uptake and prediction of permeability along the GI tract.

Breaking the Silence: An Epidemiological Report on Asian American and Pacific Islander Youth Mental Health and Suicide (1999-2021).

BACKGROUND: Limited studies have focused on recent trends in Asian American and Pacific Islander (AAPI) youth suicide. This study aimed to evaluate epidemiological trends in AAPI youth suicide and reports of depressive symptoms among Asian and Pacific Islander youth in the USA. METHODS: This cross-sectional study analyzed mortality data from the Centers for Disease Control Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER) and reports of depressive symptoms from the Youth Risk Behaviour Surveillance System (YRBSS). Data from 1999 to 2021 were analyzed for suicide rates and methods used among AAPI youth aged 5-24 years. YRBSS data from 1991 to 2021 were analyzed for depressive symptoms reported by Asian American (AA) 9th-12th graders. RESULTS: From 1999 to 2021, 4747 AAPI youth died by suicide in the USA. Rates of suicide doubled from 3.6 to 7.1 per 100,000 during 1999-2021, with an increasing trend observed from 2014 onwards. The most common methods of suicide deaths in this population were suffocation, firearms and poisoning. Rates of suicide were higher among AA males than females, although more AA females reported depressive symptoms, including suicidal planning and attempts. CONCLUSION: This study shows a concerning increase in suicide rates among AAPI youth over 1999-2021. Suffocation, firearms and poisoning were the most common methods used. While more AAPI males died by suicide, AA females reported higher rates of depressive symptoms. These findings highlight the urgent need for targeted prevention strategies and clinical interventions for this vulnerable population. The study also emphasizes the importance of addressing mental health stigma to improve reporting and support for Asian American, Native Hawaiian and Pacific Islander (AANHPI) youth.

Pharmacokinetics of Budesonide Oral Suspension in Children and Adolescents With Eosinophilic Esophagitis.

The pharmacokinetic (PK) profile of budesonide oral suspension (BOS) was evaluated during a phase 2, randomized, double-blind, placebo-controlled, dose-ranging study in pediatric patients with eosinophilic esophagitis (EoE) (MPI 101-01/NCT00762073). Non-compartmental methods were used to calculate PK parameters in 37 patients after receiving morning doses of BOS, with volume and dose adjusted for age (low dose: 0.35 or 0.5 mg; high dose: 1.4 or 2.0 mg [2-9 or 10-18 years old, respectively]). Relationships between apparent oral clearance and volume of distribution, and bodyweight and body mass index were also evaluated. Budesonide systemic exposure increased with BOS dose. After oral administration, time to maximum plasma budesonide concentration occurred ~1 hour post dose and the half-life of budesonide was 3.3-3.5 hours. PK parameters were similar between age groups for low- and high-dose BOS, indicating that volume and dose adjustments for age were appropriate for pediatric patients with EoE. BOS was well tolerated.

No clinically significant pharmacokinetic interactions between dolutegravir and daclatasvir in healthy adult subjects.

BACKGROUND: Daclatasvir (DCV) is an NS5A replication complex inhibitor recently approved for chronic hepatitis C virus treatment. METHODS: To assess drug interactions between the HIV integrase strand transfer inhibitor dolutegravir (DTG) and DCV, subjects were randomized into 1 of 2 sequences in an open-label, 3-period, crossover study. Subjects received either DTG 50 mg once daily or DCV 60 mg once daily for 5 days in periods 1 and 2 and DTG 50 mg plus DCV 60 mg once daily for 5 days in period 3, with no washout between periods 2 and 3. Between periods 1 and 2, there was a washout period of at least 7 days. RESULTS: The geometric least-squares mean ratios (90 % confidence intervals) of DCV area under the concentration-time curve over a dosing interval (AUC0-τ), maximum observed concentration (Cmax), and concentration at the end of the dosing interval (Cτ) were 0.978 (0.831-1.15), 1.03 (0.843-1.25), and 1.06 (0.876-1.29), respectively, when DCV was administered with DTG compared with DCV alone. Compared with DTG alone, coadministration of DTG with DCV increased DTG AUC0-τ, Cmax, and Cτ by approximately 33, 29, and 45 %, respectively. CONCLUSIONS: DCV plasma exposure was not meaningfully affected by DTG. Coadministration of DTG with DCV resulted in slight increases in DTG AUC0-τ, Cmax, and Cτ. Accumulated safety and tolerability data in humans receiving DTG to date suggests this effect is not considered clinically significant. DTG and DCV can be coadministered without dose adjustment. TRIAL REGISTRATION: Registered on March 6, 2014 with ClinicalTrials.gov; registration number: NCT02082808 and as Study ID: 201102 on the ViiV Clinical Study Registry.

Effect of carbamazepine on dolutegravir pharmacokinetics and dosing recommendation.

PURPOSE: Dolutegravir (DTG) is primarily metabolized by UGT1A1 with CYP3A as a minor route. Carbamazepine (CBZ) is a potent inducer of these enzymes; thus, the effect of oral extended-release CBZ on DTG pharmacokinetics (PK) was evaluated to provide dose recommendation when co-administered. METHODS: This was a single-center, open-label, fixed-sequence, crossover study in healthy adults. Subjects received three treatments: DTG 50 mg every 24 h (q24h) × 5 days in period 1, followed by CBZ 100 mg every 12 h (q12h) × 3 days, then 200 mg q12h × 3 days, then 300 mg q12h × 10 days in period 2, and DTG 50 mg q24h + CBZ 300 mg q12h × 5 days in period 3. No washout intervals occurred. Each dose was administered with a moderate-fat meal. Serial PK samples for DTG were collected on day 5 of periods 1 and 3. Plasma DTG PK parameters were determined with non-compartmental analysis. Geometric least-squares mean ratios (GMRs) and 90 % confidence intervals (CIs) were generated by the mixed-effect model for within-subject treatment comparisons. Safety assessments were performed throughout the study. RESULTS: Sixteen subjects enrolled; 14 completed the study. CBZ significantly reduced DTG exposure: GMRs (90 % CI) for DTG + CBZ versus DTG alone were 0.51 (0.48-0.549), 0.67 (0.61-0.73), and 0.27 (0.24-0.31) for area under the curve from time zero to the end of the dosing interval (AUC(0-τ)), maximum observed plasma concentration (Cmax), and plasma concentration at the end of the dosing interval (Cτ), respectively. DTG alone and co-administered with CBZ was well tolerated. CONCLUSION: Integrase strand transfer inhibitor-naive subjects taking CBZ should receive DTG 50 mg twice daily versus once daily, as is recommended with other potent UGT1A/CYP3A inducers. ClinicalTrials.gov: NCT01967771.

Population pharmacokinetics of dolutegravir in HIV-infected treatment-naive patients.

AIM: Dolutegravir is the newest integrase inhibitor approved for HIV treatment and has demonstrated potent antiviral activity in patient populations with a broad range of treatment experience. This analysis aimed to characterize the population pharmacokinetics of dolutegravir in treatment-naive patients and to evaluate the influence of patient covariates. METHODS: A population pharmacokinetic model was developed using a non-linear mixed effect modelling approach based on data from 563 HIV-infected, treatment-naive adult patients in three phase 2/3 trials who received dolutegravir (ranging from 10-50 mg once daily) alone or in combination with abacavir/lamivudine or tenofovir/emtricitabine. RESULTS: The pharmacokinetics of dolutegravir were adequately described by a linear one compartment model with first order absorption, absorption lag time and first order elimination. Population estimates for apparent clearance, apparent volume of distribution, absorption rate constant and absorption lag time were 0.901 l h(-1) , 17.4 l, 2.24 h(-1) , and 0.263 h, respectively. Weight, smoking status, age and total bilirubin were predictors of clearance, weight was a predictor of volume of distribution and gender was a predictor of bioavailability. However, the magnitude of the effects of these covariates on steady-state dolutegravir plasma exposure was relatively small (<32%) and was not considered clinically significant. Race/ethnicity, HBV/HCV co-infection, CDC classification, albumin, creatinine clearance, alanine aminotransferase or aspartate aminotransferase did not influence the pharmacokinetics of dolutegravir in this analysis. CONCLUSIONS: A population model that adequately characterizes dolutegravir pharmacokinetics has been developed. No dolutegravir dose adjustment by patient covariates is necessary in HIV-infected treatment-naive patients.

Dolutegravir Has No Effect on the Pharmacokinetics of Oral Contraceptives With Norgestimate and Ethinyl Estradiol.

BACKGROUND: Dolutegravir (DTG; Tivicay; ViiV Healthcare, Research Triangle Park, NC) is an HIV-1-unboosted integrase inhibitor with no cytochrome P450 or uridine 5'diphosphate-glucuronosyltransferase inhibition or induction. As DTG is administered to HIV-1-infected women receiving oral contraceptives, assessing the potential for drug interactions was warranted. OBJECTIVE: To determine the impact of DTG on the pharmacokinetics (PK) and pharmacodynamics (PD) of a common oral contraceptive, norgestimate/ethinyl estradiol (NGM/EE; Ortho-Cyclen; Ortho-McNeil-Janssen Pharmaceuticals, Inc, Raritan, NJ). METHODS: This randomized, 2-period, double-blind, placebo-controlled study was conducted within 1 menstrual cycle at 1 clinical center in the United States; 16 women were enrolled. Participants received NGM 0.25 mg/EE 0.035 mg throughout the study. During days 1 to 10, they were randomized to receive twice-daily DTG 50 mg or matching placebo with food and switched to the other treatment during days 12 to 21. RESULTS: Ratios of area under the concentration-time curve from time 0 until end of the dosage interval (AUC0-τ), maximum plasma concentration, and concentration at the end of the dosage interval of norelgestromin with DTG treatment to the same PK parameters with placebo treatment were 0.975, 0.890, and 0.932, respectively; for EE, ratios were 1.03, 0.99, and 1.02, respectively. No significant differences in luteinizing hormone, follicle-stimulating hormone, and progesterone were detected on days 1, 10, 11, 21, and 22. DTG steady-state AUC0-τ was similar to historical data. No severe or grade 3/4 adverse events occurred. CONCLUSIONS: DTG had no effect on NGM/EE PK or PD. NGM/EE can be administered with DTG without dose adjustment.

Dolutegravir in antiretroviral-experienced patients with raltegravir- and/or elvitegravir-resistant HIV-1: 24-week results of the phase III VIKING-3 study.

BACKGROUND: The pilot phase IIb VIKING study suggested that dolutegravir (DTG), a human immunodeficiency virus (HIV) integrase inhibitor (INI), would be efficacious in INI-resistant patients at the 50 mg twice daily (BID) dose. METHODS: VIKING-3 is a single-arm, open-label phase III study in which therapy-experienced adults with INI-resistant virus received DTG 50 mg BID while continuing their failing regimen (without raltegravir or elvitegravir) through day 7, after which the regimen was optimized with ≥1 fully active drug and DTG continued. The primary efficacy endpoints were the mean change from baseline in plasma HIV-1 RNA at day 8 and the proportion of subjects with HIV-1 RNA <50 c/mL at week 24. RESULTS: Mean change in HIV-1 RNA at day 8 was -1.43 log10 c/mL, and 69% of subjects achieved <50 c/mL at week 24. Multivariate analyses demonstrated a strong association between baseline DTG susceptibility and response. Response was most reduced in subjects with Q148 + ≥2 resistance-associated mutations. DTG 50 mg BID had a low (3%) discontinuation rate due to adverse events, similar to INI-naive subjects receiving DTG 50 mg once daily. CONCLUSIONS: DTG 50 mg BID-based therapy was effective in this highly treatment-experienced population with INI-resistant virus. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov (NCT01328041) and http://www.gsk-clinicalstudywww.gsk-clinicalstudyregister.com (112574).

ING116070: a study of the pharmacokinetics and antiviral activity of dolutegravir in cerebrospinal fluid in HIV-1-infected, antiretroviral therapy-naive subjects.

BACKGROUND: Dolutegravir (DTG), a once-daily, human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, was evaluated for distribution and antiviral activity in cerebrospinal fluid (CSF). METHODS: ING116070 is an ongoing, single-arm, open-label, multicenter study in antiretroviral therapy-naive, HIV-1-infected adults. Subjects received DTG (50 mg) plus abacavir/lamivudine (600/300 mg) once daily. The CSF and plasma (total and unbound) DTG concentrations were measured at weeks 2 and 16. The HIV-1 RNA levels were measured in CSF at baseline and weeks 2 and 16 and in plasma at baseline and weeks 2, 4, 8, 12, and 16. RESULTS: Thirteen white men enrolled in the study; 2 withdrew prematurely, 1 because of a non-drug-related serious adverse event (pharyngitis) and 1 because of lack of treatment efficacy. The median DTG concentrations in CSF were 18 ng/mL (range, 4-23 ng/mL) at week 2 and 13 ng/mL (4-18 ng/mL) at week 16. Ratios of DTG CSF to total plasma concentration were similar to the unbound fraction of DTG in plasma. Median changes from baseline in CSF (n = 11) and plasma (n = 12) HIV-1 RNA were -3.42 and -3.04 log10 copies/mL, respectively. Nine of 11 subjects (82%) had plasma and CSF HIV-1 RNA levels <50 copies/mL and 10 of 11 (91%) had CSF HIV-1 RNA levels <2 copies/mL at week 16. CONCLUSIONS: The DTG concentrations in CSF were similar to unbound plasma concentrations and exceeded the in vitro 50% inhibitory concentration for wild-type HIV (0.2 ng/mL), suggesting that DTG achieves therapeutic concentrations in the central nervous system. The HIV-1 RNA reductions were similar in CSF and plasma. Clinical Trials Registration. NCT01499199.

Effect of fosamprenavir-ritonavir on the pharmacokinetics of dolutegravir in healthy subjects.

Dolutegravir (DTG) is an HIV integrase inhibitor (INI) with demonstrated activity in INI-naive and INI-resistant patients. The objective of this open-label, 2-period, single-sequence study was to evaluate the effect of fosamprenavir-ritonavir (FPV-RTV) on the steady-state plasma pharmacokinetics of DTG. Twelve healthy subjects received 50 mg DTG once daily for 5 days (period 1), followed by 10 days of 50 mg DTG once daily in combination with 700/100 mg FPV-RTV every 12 h (period 2). All doses were administered in the fasting state. Serial pharmacokinetic samples for DTG and amprenavir and safety assessments were obtained throughout the study. Noncompartmental pharmacokinetic analysis was performed, and geometric least-squares mean ratios and 90% confidence intervals were generated for within-subject treatment comparison. Fosamprenavir-ritonavir decreased the DTG area under the concentration-time curve, maximum concentration in plasma, and concentration in plasma at the end of the dosing interval by 35%, 24%, and 49%, respectively. Both DTG and DTG with FPV-RTV were well tolerated; no subject withdrew because of adverse events. The most frequently reported drug-related adverse events were rash, abnormal dreams, and nasopharyngitis. The modest decrease in DTG exposure when it was coadministered with FPV-RTV is not considered clinically significant, and DTG dose adjustment is not required with coadministration of FPV-RTV in INI-naive patient populations on the basis of established "no-effect" boundaries of DTG. In the INI-resistant population, as a cautionary measure, alternative combinations that do not include FPV-RTV should be considered. (This study has been registered at ClinicalTrials.gov under identifier NCT01209065.).

Effects of enzyme inducers efavirenz and tipranavir/ritonavir on the pharmacokinetics of the HIV integrase inhibitor dolutegravir.

PURPOSE: Dolutegravir (DTG) is an unboosted, integrase inhibitor for the treatment of HIV infection. Two studies evaluated the effects of efavirenz (EFV) and tipranavir/ritonavir (TPV/r) on DTG pharmacokinetics (PK) in healthy subjects. METHODS: The first study was an open-label crossover where 12 subjects received DTG 50 mg every 24 hours (q24h) for 5 days, followed by DTG 50 mg and EFV 600 mg q24h for 14 days. The second study was an open-label crossover where 18 subjects received DTG 50 mg q24h for 5 days followed by TPV/r 500/200 mg every 12 hours (q12h) for 7 days and then DTG 50 mg q24h and TPV/r 500/200 mg q12h for a further 5 days. Safety assessments and serial PK samples were collected. Non-compartmental PK analysis and geometric mean ratios and 90% confidence intervals were generated. RESULTS: The combination of DTG with EFV or TPV/r was generally well tolerated. Four subjects discontinued the TPV/r study due to increases in alanine aminotransferase that were considered related to TPV/r. Co-administration with EFV resulted in decreases of 57, 39 and 75% in DTG AUC(0-τ), Cmax and Cτ, respectively. Co-administration with TPV/r resulted in decreases of 59, 46 and 76% in DTG AUC(0-τ), Cmax and Cτ, respectively. CONCLUSIONS: Given the reductions in exposure and PK/pharmacodynamic relationships in phase II/III trials, DTG should be given at an increased dose of 50 mg twice daily when co-administered with EFV or TPV/r, and alternative regimens without inducers should be considered in integrase inhibitor-resistant patients.

Maribavir: Mechanism of action, clinical, and translational science.

Maribavir is an oral benzimidazole riboside for treatment of post-transplant cytomegalovirus (CMV) infection/disease that is refractory to prior antiviral treatment (with or without resistance). Through competitive inhibition of adenosine triphosphate, maribavir prevents the phosphorylation actions of UL97 to inhibit CMV DNA replication, encapsidation, and nuclear egress. Maribavir is active against CMV strains with viral DNA polymerase mutations that confer resistance to other CMV antivirals. After oral administration, maribavir is rapidly and highly absorbed (fraction absorbed >90%). The approved dose of 400 mg twice daily (b.i.d.) achieves a steady-state area under the curve per dosing interval of 128 h*µg/mL and trough concentration of 4.90 µg/mL (13.0 µM). Maribavir is highly bound to human plasma proteins (98%) with a small apparent volume of distribution of 27.3 L. Maribavir is primarily cleared by hepatic CYP3A4 metabolism; its major metabolite, VP44669 (pharmacologically inactive), is excreted in the urine and feces. There is no clinically relevant impact on maribavir pharmacokinetics by age, sex, race/ethnicity, body weight, transplant type, or hepatic/renal impairment status. In phase II dose-ranging studies, maribavir showed similar rates of CMV viral clearance across 400, 800, or 1200 mg b.i.d. groups, ranging from 62.5-70% in study 202 (NCT01611974) and 74-83% in study 203 (EudraCT 2010-024247-32). In the phase III SOLSTICE trial (NCT02931539), maribavir 400 mg b.i.d. demonstrated superior CMV viremia clearance at week 8 versus investigator-assigned treatments, with lower treatment discontinuation rates. Dysgeusia, nausea, vomiting, and diarrhea were commonly experienced adverse events among patients treated with maribavir in clinical trials.

Effect of Food, Crushing of Tablets, and Antacid Coadministration on Maribavir Pharmacokinetics in Healthy Adult Participants: Results From 2 Phase 1, Open-Label, Randomized, Crossover Studies.

The effect of food composition, tablet crushing, and antacid coadministration on maribavir pharmacokinetics was assessed in 2 Phase 1 studies in healthy adults. In the first, a single maribavir 400-mg dose was administered under fasting conditions, with a low-fat/low-calorie or a high-fat/high-calorie meal. In the second, a single maribavir 100-mg dose was administered under fasting conditions, as a crushed tablet, or as a whole tablet alone or with an antacid. The 90% confidence intervals of the geometric mean ratios were within 80%-125% for area under the concentration-time curve (AUC), but not for maximum plasma concentration (Cmax) for low-fat/low-calorie and high-fat/high-calorie meals versus fasting or for whole tablet with antacid versus whole tablet alone. The 90% confidence intervals of the geometric mean ratios for AUC and Cmax were within 80%-125% for crushed versus whole tablet. Maribavir median time to Cmax value in plasma under fed conditions was delayed versus fasting conditions, but there was no statistical difference for crushed versus whole tablet or with versus without antacid. As the antiviral efficacy of maribavir is driven by AUC but not Cmax, findings suggest that maribavir can be administered with food or antacids or as a crushed tablet.

Effect of prednisone on the pharmacokinetics of the integrase inhibitor dolutegravir.

Prednisone, a corticosteroid frequently used to treat common AIDS-related illnesses and comorbidities, has been shown to induce drug metabolism. This study was performed to determine whether prednisone coadministration affected the pharmacokinetics of dolutegravir (DTG). In this open-label, repeat-dose study, 12 healthy subjects were administered DTG at 50 mg daily alone for 5 days and then with concomitant prednisone for 10 days (prednisone at 60 mg daily for 5 days, followed by a 5-day taper). Serial blood sampling and safety assessments were performed during the trial. Pharmacokinetic parameters were determined using noncompartmental methods and geometric least-square mean ratios, and 90% confidence intervals were generated. Coadministration of DTG and 5-day high-dose prednisone with a 5-day taper had a modest effect on DTG exposure. The area under the DTG plasma concentration-time curve, maximum observed DTG concentration, and 24-hour postdose DTG concentration were increased by 11%, 6%, and 17%, respectively, on day 10 of the combination. Similar results were observed after 5 days of DTG and prednisone. Dolutegravir and prednisone coadministration was well tolerated. The changes in plasma exposures of DTG in healthy individuals as a result of prednisone dosing were not clinically significant. No dose adjustment is required for DTG coadministered with prednisone. (This study has been registered at ClinicalTrials.gov under registration no. NCT01425099.).

Metabolism, excretion, and mass balance of the HIV-1 integrase inhibitor dolutegravir in humans.

The pharmacokinetics, metabolism, and excretion of dolutegravir, an unboosted, once-daily human immunodeficiency virus type 1 integrase inhibitor, were studied in healthy male subjects following single oral administration of [(14)C]dolutegravir at a dose of 20 mg (80 µCi). Dolutegravir was well tolerated, and absorption of dolutegravir from the suspension formulation was rapid (median time to peak concentration, 0.5 h), declining in a biphasic fashion. Dolutegravir and the radioactivity had similar terminal plasma half-lives (t1/2) (15.6 versus 15.7 h), indicating metabolism was formation rate limited with no long-lived metabolites. Only minimal association with blood cellular components was noted with systemic radioactivity. Recovery was essentially complete (mean, 95.6%), with 64.0% and 31.6% of the dose recovered in feces and urine, respectively. Unchanged dolutegravir was the predominant circulating radioactive component in plasma and was consistent with minimal presystemic clearance. Dolutegravir was extensively metabolized. An inactive ether glucuronide, formed primarily via UGT1A1, was the principal biotransformation product at 18.9% of the dose excreted in urine and the principal metabolite in plasma. Two minor biotransformation pathways were oxidation by CYP3A4 (7.9% of the dose) and an oxidative defluorination and glutathione substitution (1.8% of the dose). No disproportionate human metabolites were observed.

A phase 1 study to evaluate the effect of dolutegravir on renal function via measurement of iohexol and para-aminohippurate clearance in healthy subjects.

AIM: Dolutegravir (DTG; S/GSK1349572) is under clinical development as a once daily, unboosted integrase inhibitor for the treatment of HIV infection. The effect of DTG on glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and creatinine clearance (CLcr ) was evaluated in 34 healthy volunteers. METHODS: Subjects received DTG 50 mg (once daily or twice daily) or placebo for 14 days. GFR was measured by iohexol plasma clearance, ERPF was assessed by para-aminohippurate plasma clearance and CLcr was measured by 24 h urine collection. RESULTS: All treatments were generally well tolerated. A modest decrease (10-14%) in CLcr was observed, consistent with clinical study observations. DTG 50 mg once daily and twice daily had no significant effect on GFR or ERPF compared with placebo over 14 days in healthy subjects. CONCLUSIONS: These findings support in vitro data that DTG increases serum creatinine by the benign inhibition of the organic cation transporter 2, which is responsible for tubular secretion of creatinine.

Maribavir Pharmacokinetics and Safety in Participants With Moderate Hepatic Impairment: A Phase 1, Open-Label, Single-Dose, Parallel Group Study.

Maribavir, an orally bioavailable antiviral, has shown superior activity against posttransplant cytomegalovirus infection compared with conventional antivirals. It is primarily metabolized in the liver. This open-label, single-center study evaluated the effect of hepatic impairment on the pharmacokinetics of maribavir in nontransplant participants. A single 200-mg dose of maribavir was administered orally under fasting conditions to participants with moderate hepatic impairment (Child-Pugh class B) (n = 10) and healthy controls (n = 10) matched for age, weight, sex, and smoking status. Compared with participants with normal hepatic function, maximum plasma concentration (Cmax ) and area under the plasma concentration-time curve (AUC) from time 0 to infinity values for maribavir in participants with moderate hepatic impairment were 1.346-fold (90%CI of geometric mean ratio, 1.091-1.660) and 1.261-fold (0.889-1.787) higher, respectively. However, Cmax and AUC values for unbound maribavir were comparable. For VP 44469, the main metabolite of maribavir, the Cmax and AUC from time 0 to infinity values were 1.190-fold (0.836-1.693) and 1.309-fold (1.007-1.702) higher, respectively, in participants with moderate hepatic impairment. In total, 7 mild treatment-emergent adverse events were reported, all in the moderate hepatic impairment group. Dysgeusia was the most frequently reported treatment-emergent adverse event, at a frequency of 50%. These results indicated that total maribavir concentrations were mildly increased in participants with moderate hepatic impairment, while unbound concentrations were unaffected. Similar maribavir pharmacokinetics in participants with moderate hepatic impairment and normal hepatic function suggest that dose adjustment may not be required for patients with moderate hepatic impairment.

Pharmacokinetics and Safety Evaluation of Maribavir in Healthy Japanese and Matched White Participants: A Phase 1, Open-Label Study.

This phase I study compared pharmacokinetics and safety of maribavir in Japanese and White participants, and evaluated dose proportionality in Japanese participants. Under fasting conditions, 12 healthy adult participants of Japanese descent and 12 matched White participants received a single 400-mg dose of maribavir. Japanese participants received 2 further doses of maribavir: 200 mg and 800 mg, or 800 mg and 200 mg, separated by a ≥72-hour washout period. Serial blood samples were collected up to 24 hours after dosing for pharmacokinetic assessments. Following the 400-mg dose, the geometric mean ratios (90% confidence interval) of Japanese versus White participants were 110% (91.7%-133%) for maximum plasma concentration, 122% (96.8%-155%) for area under the plasma concentration-time curve (AUC) from time of dosing to the last measurable concentration, and 125% (98.0%-160%) for AUC extrapolated to infinity. In Japanese participants, maribavir AUC extrapolated to infinity and AUC from time of dosing to the last measurable concentration increased in a dose-proportional fashion over 200-800 mg; maximum plasma concentration increased less than dose proportionally. Seven participants reported treatment-emergent adverse events (TEAEs; Japanese participants, 400 mg: 2 [16.7%], 200 mg: 1 [8.3%]; White participants, 400 mg: 4 [33.3%]), all mild and most commonly dysgeusia. No serious TEAEs or TEAEs leading to discontinuation were reported. This study demonstrated higher maribavir systemic exposure in Japanese than White participants and similar safety outcomes. This difference in exposure is not considered clinically important and its significance remains to be determined.

Population pharmacokinetic modeling and simulation of maribavir to support dose selection and regulatory approval in adolescents with posttransplant refractory cytomegalovirus.

Maribavir was approved by the US Food and Drug Administration for the treatment of patients aged ≥12 years and weighing ≥35 kg with posttransplant cytomegalovirus infection/disease refractory (with/without resistance) to valganciclovir, ganciclovir, cidofovir, or foscarnet, with an oral dose of 400 mg twice daily. With no pediatric clinical data available and difficulty in trial recruitment, population pharmacokinetic modeling and simulations were conducted to predict the pharmacokinetics and inform maribavir dosing in adolescents.

Physiologically Based Pharmacokinetic Modeling for Maribavir to Inform Dosing in Drug-Drug Interaction Scenarios with CYP3A4 Inducers and Inhibitors.

Maribavir, an orally available antiviral agent, has been approved in multiple countries for the treatment of patients with refractory post-transplant cytomegalovirus (CMV) infection and/or disease. Maribavir is primarily metabolized by CYP3A4; coadministration with CYP3A4 inducers and inhibitors may significantly alter maribavir exposure, thereby affecting its efficacy and safety. The effect of CYP3A4 inducers and inhibitors on maribavir exposure was evaluated based on a drug-drug interaction (DDI) study and physiologically-based pharmacokinetic (PBPK) modeling. The effect of rifampin (a strong inducer of CYP3A4 and moderate inducer of CYP1A2), administered at a 600 mg dose once daily, on maribavir pharmacokinetics was assessed in a clinical phase 1 DDI study in healthy participants. A full PBPK model for maribavir was developed and verified using in vitro and clinical pharmacokinetic data from phase 1 studies. The verified PBPK model was then used to simulate maribavir DDI interactions with various CYP3A4 inducers and inhibitors. The DDI study results showed that coadministration with rifampin decreased the maribavir maximum plasma concentration (Cmax ), area under the plasma concentration-time curve (AUC), and trough concentration (Ctrough ) by 39%, 60%, and 82%, respectively. Based on the results from the clinical DDI study, the coadministration of maribavir with rifampin is not recommended. The PBPK model did not predict a clinically significant effect of CYP3A4 inhibitors on maribavir exposure; however, it predicted that strong or moderate CYP3A4 inducers, including carbamazepine, efavirenz, phenobarbital, and phenytoin, may reduce maribavir exposure to a clinically significant extent, and may prompt the consideration of a maribavir dosing increase, in accordance with local approved labels and/or regulations.