Phase 1 Studies to Assess Inhaled Seralutinib as a Perpetrator or a Victim of Drug-Drug Interactions in Healthy Participants.

Seralutinib, an inhaled, small-molecule tyrosine kinase inhibitor in clinical development for the treatment of pulmonary arterial hypertension (PAH), was evaluated for its potential as a perpetrator or victim of a metabolic and transporter-based drug-drug interactions in 2 phase 1 studies. In study 1, 24 participants received a cocktail of probe substrates: caffeine (CYP1A2), montelukast (CYP2C8), flurbiprofen (CYP2C9), midazolam (CYP3A), and pravastatin (OATP1B1/1B3), plus digoxin (P-gp) with or without seralutinib. In study 2, 19 participants received seralutinib with/without itraconazole, a strong CYP3A inhibitor, or fosaprepitant, a weak CYP3A inhibitor.

Exposure-response relationships for the efficacy and safety of filgotinib and its metabolite GS-829845 in subjects with rheumatoid arthritis based on phase 2 and phase 3 studies.

Aims: Filgotinib is a potent, oral, JAK1-preferential inhibitor for the treatment of rheumatoid arthritis (RA). This report describes exposure-response (ER) analyses of filgotinib for dose confirmation based on three phase 3 and two phase 2 studies in moderate to severe RA patients.

Methods: The pharmacokinetic exposures used in ER analyses were derived from population pharmacokinetic analysis.

Pharmacokinetic, Pharmacodynamic, and Drug-Interaction Profile of Remdesivir, a SARS-CoV-2 Replication Inhibitor.

Remdesivir (RDV, Veklury) is a once-daily, nucleoside ribonucleic acid polymerase inhibitor of severe acute respiratory syndrome coronavirus 2 replication. Remdesivir has been granted approvals in several countries for use in adults and children hospitalized with severe coronavirus disease 2019 (COVID-19). Inside the cell, remdesivir undergoes metabolic activation to form the intracellular active triphosphate metabolite, GS-443902 (detected in peripheral blood mononuclear cells), and ultimately, the renally eliminated plasma metabolite GS-441524.

Validation of LC-MS/MS methods for determination of remdesivir and its metabolites GS-441524 and GS-704277 in acidified human plasma and their application in COVID-19 related clinical studies.

Remdesivir (RDV) is a phosphoramidate prodrug designed to have activity against a broad spectrum of viruses. Following IV administration, RDV is rapidly distributed into cells and tissues and simultaneously metabolized into GS-441524 and GS-704277 in plasma. LC-MS/MS methods were validated for determination of the 3 analytes in human plasma that involved two key aspects to guarantee their precision, accuracy and robustness.

Physiologically-Based Pharmacokinetic Modeling of Remdesivir and Its Metabolites to Support Dose Selection for the Treatment of Pediatric Patients With COVID-19.

Severe coronavirus disease 2019 (COVID-19) disease, including multisystem inflammatory syndrome, has been reported in children. This report summarizes development of a remdesivir physiologically-based pharmacokinetic (PBPK) model that accurately describes observed adult remdesivir and metabolites exposure and predicts pediatric remdesivir and metabolites exposure. The adult PBPK model was applied to predict pediatric remdesivir and metabolites steady-state exposures using the Pediatric Population Model in SimCYP and incorporated the relevant physiologic and mechanistic information.

Organic Anion Transporting Polypeptide Inhibition Dramatically Increases Plasma Exposure but not Pharmacodynamic Effect nor Inferred Hepatic Intracellular Exposure of Firsocostat.

Firsocostat (FIR: previously GS-0976), a highly sensitive OATP substrate, reduces hepatic de novo lipogenesis (DNL) by inhibiting acetyl-CoA carboxylases (ACC). Measuring the pharmacodynamic (PD) efficacy of FIR on DNL provides a unique opportunity to determine optimal dosing strategies for liver-targeted OATP substrates in settings of altered OATP function. A randomized, four-way crossover drug-drug interaction study was conducted.

Phase 1b study to investigate the safety and tolerability of idelalisib in Japanese patients with relapsed/refractory follicular lymphoma and chronic lymphocytic leukemia.

Objective: Idelalisib is an orally administered, highly selective inhibitor of phosphatidylinositol 3-kinase-δ. In this phase 1b study, the safety, tolerability and pharmacokinetics of idelalisib, an oral inhibitor of phosphatidylinositol 3-kinase-δ, were evaluated in Japanese patients with relapsed or refractory indolent B-cell non-Hodgkin lymphoma.

Methods: In total, six patients (follicular lymphoma: n = 3, chronic lymphocytic leukemia: n = 3) were enrolled to receive idelalisib 150 mg twice daily.

Emtricitabine and tenofovir alafenamide vs emtricitabine and tenofovir disoproxil fumarate for HIV pre-exposure prophylaxis (DISCOVER): primary results from a randomised, double-blind, multicentre, active-controlled, phase 3, non-inferiority trial.

Background: Tenofovir alafenamide shows high antiviral efficacy and improved renal and bone safety compared with tenofovir disoproxil fumarate when used for HIV treatment. Here, we report primary results from a blinded phase 3 study evaluating the efficacy and safety of pre-exposure prophylaxis (PrEP) with emtricitabine and tenofovir alafenamide versus emtricitabine and tenofovir disoproxil fumarate for HIV prevention.

Methods: This study is an ongoing, randomised, double-blind, multicentre, active-controlled, phase 3, non-inferiority trial done at 94 community, public health, and hospital-associated clinics located in regions of Europe and North America, where there is a high incidence of HIV or prevalence of people living with HIV, or both.

Safety, pharmacokinetics and pharmacodynamics of selgantolimod, an oral Toll-like receptor 8 agonist: a Phase Ia study in healthy subjects.

Background: Selgantolimod is a novel oral, selective Toll-like receptor 8 (TLR8) agonist in development for the treatment of chronic hepatitis B (CHB). TLR8 is an endosomal innate immune receptor and a target for treatment of viral infections. This first-in-human study investigated the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of selgantolimod in healthy volunteers.

Safety, Tolerability, and Pharmacokinetics of Remdesivir, An Antiviral for Treatment of COVID-19, in Healthy Subjects.

Remdesivir (RDV), a single diastereomeric monophosphoramidate prodrug that inhibits viral RNA polymerases, has potent in vitro antiviral activity against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). RDV received the US Food and Drug Administration (FDA)'s emergency use authorization in the United States and approval in Japan for treatment of patients with severe coronavirus disease 2019 (COVID-19). This report describes two phase I studies that evaluated the safety and pharmacokinetics (PKs) of single escalating and multiple i.

Pharmacokinetics, Safety, and Tolerability of Selonsertib, an Apoptosis Signal-Regulating Kinase 1 (ASK1) Inhibitor, Following First-in-Human Single and Multiple Ascending Doses in Healthy Subjects.

Background: Selonsertib is a first-in-class inhibitor of apoptosis signal-regulating kinase 1 (ASK1) with therapeutic potential for fibrotic diseases. This phase I study evaluated the safety, tolerability, pharmacokinetics (PK), and food effect of selonsertib in healthy subjects.

Methods: This was a double-blinded, randomized, placebo-controlled dose-escalation study.

Filgotinib, a JAK1 Inhibitor, Has No Effect on QT Interval in Healthy Subjects.

Filgotinib, a selective inhibitor of Janus kinase 1, is being developed for the treatment of chronic inflammatory diseases. Electrocardiograms evaluated the effect of filgotinib on the corrected QT (QTc) interval in 52 healthy subjects who received each of 4 treatments: filgotinib 200 mg (therapeutic dose), 450 mg (supratherapeutic dose), and placebo, each administered once daily for 7 days, and a single dose of moxifloxacin 400 mg (positive control). Plasma samples were collected for pharmacokinetic analysis.

A Comparison of Total and Plasma Membrane Abundance of Transporters in Suspended, Plated, Sandwich-Cultured Human Hepatocytes Versus Human Liver Tissue Using Quantitative Targeted Proteomics and Cell Surface Biotinylation.

Suspended (SH), plated (PH), and sandwich-cultured hepatocytes (SCH) are commonly used models to predict in vivo transporter-mediated hepatic uptake (SH or PH) or biliary (SCH) clearance of drugs. When doing so, the total and the plasma membrane abundance (PMA) of transporter are assumed not to differ between hepatocytes and liver tissue (LT). This assumption has never been tested.

Abundance of Phase 1 and 2 Drug-Metabolizing Enzymes in Alcoholic and Hepatitis C Cirrhotic Livers: A Quantitative Targeted Proteomics Study.

To predict the impact of liver cirrhosis on hepatic drug clearance using physiologically based pharmacokinetic (PBPK) modeling, we compared the protein abundance of various phase 1 and phase 2 drug-metabolizing enzymes (DMEs) in S9 fractions of alcoholic ( = 27) or hepatitis C (HCV, = 30) cirrhotic versus noncirrhotic (control) livers ( = 25). The S9 total protein content was significantly lower in alcoholic or HCV cirrhotic versus control livers (i.e.

The Drug-Drug Interaction Potential of Antiviral Agents for the Treatment of Chronic Hepatitis C Infection.

Several safe and highly effective direct-acting antiviral (DAA) drugs for chronic hepatitis C virus (HCV) have been developed and greatly increase the number of therapeutic options available to successfully treat HCV infection. However, because treatment regimens contain at least two drugs (e.g.

Phase 1 First-in-Human, Single- and Multiple-Ascending Dose, and Food Effect Studies to Assess the Safety, Tolerability, and Pharmacokinetics of Presatovir for the Treatment of Respiratory Syncytial Virus Infection.

Respiratory syncytial virus (RSV)-associated respiratory tract infection is a leading cause of hospitalizations in infants for which no effective treatment exists. RSV infection is also an important cause of respiratory disease in adults and immunocompromised patients. Presatovir (GS-5806) is an orally bioavailable antiviral agent that inhibits fusion of RSV with host cell membranes.

Drug-Drug Interaction Profile of the Fixed-Dose Combination Tablet Regimen Ledipasvir/Sofosbuvir.

Ledipasvir/sofosbuvir (Harvoni), a fixed-dose combination tablet of an NS5A inhibitor ledipasvir and an NS5B polymerase inhibitor sofosbuvir, is approved for the treatment of chronic hepatitis C virus infection. Ledipasvir/sofosbuvir exhibits a favorable drug-drug interaction profile and can be administered with various medications that may be used by hepatitis C virus-infected patients, including patients with comorbidities, such as co-infection with human immunodeficiency virus or immunosuppression following liver transplantation. Ledipasvir/sofosbuvir is not expected to act as a victim or perpetrator of cytochrome P450- or UDP-glucuronosyltransferase 1A1-mediated drug-drug interactions.

Cytochrome P450 3A Induction Predicts P-glycoprotein Induction; Part 1: Establishing Induction Relationships Using Ascending Dose Rifampin.

Drug transporter and cytochrome P450 expression is regulated by shared nuclear receptors and, hence, an inducer should induce both, although the magnitude may differ. The objective of this study was to establish relative induction relationships between CYP3A and drug transporters (P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP), and breast cancer resistance protein (BCRP)) or other P450s (CYP2C9 and CYP1A2) using ascending doses of the prototypical pregnane xenobiotic receptor (PXR) agonist, rifampin, to elicit weak, moderate, and strong PXR agonism. Healthy subjects received dabigatran etexilate, pravastatin, rosuvastatin, and a midazolam/tolbutamide/caffeine cocktail before and after rifampin 2, 10, 75, or 600 mg q.

Cytochrome P450 3A Induction Predicts P-glycoprotein Induction; Part 2: Prediction of Decreased Substrate Exposure After Rifabutin or Carbamazepine.

Rifampin demonstrated dose-dependent relative induction between cytochrome P (CYP)3A and P-glycoprotein (P-gp), organic anion transporting polypeptides (OATPs), or CYP2C9; P-gp, OATP, and CYP2C9 induction was one drug-drug interaction (DDI) category lower than that observed for CYP3A across a wide range of pregnane X receptor (PXR) agonism. The objective of this study was to determine if these relationships could be utilized to predict transporter induction by other CYP3A inducers (rifabutin and carbamazepine) and of another P-gp substrate, sofosbuvir. Healthy subjects received sofosbuvir and a six-probe drug cassette before and after 300 mg q.

Drug-Drug Interaction Studies Between Hepatitis C Virus Antivirals Sofosbuvir/Velpatasvir and Boosted and Unboosted Human Immunodeficiency Virus Antiretroviral Regimens in Healthy Volunteers.

Background: Combining antiviral regimens in the hepatitis C virus (HCV)/human immunodeficiency virus (HIV)-coinfected population can be complex as they share overlapping mechanisms for elimination that may result in drug interactions. The pharmacokinetics, safety, and tolerability of sofosbuvir/velpatasvir (SOF/VEL) with multiple antiretroviral (ARV) regimens were evaluated.

Methods: Healthy volunteers were enrolled into 2 phase 1, open-label, randomized, multiple-dose, cross-over studies.

Pharmacokinetics and Safety of Velpatasvir and Sofosbuvir/Velpatasvir in Subjects with Hepatic Impairment.

Background: The pharmacokinetics and safety of velpatasvir, a potent pangenotypic hepatitis C virus NS5A inhibitor, were evaluated in two hepatic impairment studies: a phase I study in hepatitis C virus-uninfected subjects and a phase III study (ASTRAL-4) in hepatitis C virus-infected patients.

Methods: In the phase I study, subjects with moderate or severe hepatic impairment (Child-Pugh-Turcotte Class B or C), and demographically matched subjects with normal hepatic function received a single dose of velpatasvir 100 mg. Pharmacokinetics and safety assessments were performed, and pharmacokinetic parameters were calculated using non-compartmental methods and summarized using descriptive statistics and compared statistically by geometric least-squares mean ratios and 90% confidence intervals.

Sofosbuvir and Ribavirin Liver Pharmacokinetics in Patients Infected with Hepatitis C Virus.

Sofosbuvir and ribavirin exert their anti-hepatitis C virus (anti-HCV) activity following metabolic activation in the liver. However, intrahepatic concentrations of the pharmacologically active nucleotide metabolites in humans are poorly characterized due to the inaccessibility of tissue and technical challenges with measuring nucleotide levels. A clinical study assessing the efficacy of sofosbuvir and ribavirin administered prior to liver transplantation to prevent HCV recurrence provided a unique opportunity to quantify nucleotide concentrations in human liver.

Transporter Expression in Noncancerous and Cancerous Liver Tissue from Donors with Hepatocellular Carcinoma and Chronic Hepatitis C Infection Quantified by LC-MS/MS Proteomics.

Protein expression of major hepatobiliary drug transporters (NTCP, OATPs, OCT1, BSEP, BCRP, MATE1, MRPs, and P-gp) in cancerous (C, = 8) and adjacent noncancerous (NC, = 33) liver tissues obtained from patients with chronic hepatitis C with hepatocellular carcinoma (HCV-HCC) were quantified by LC-MS/MS proteomics. Herein, we compare our results with our previous data from noninfected, noncirrhotic (control, = 36) and HCV-cirrhotic ( = 30) livers. The amount of membrane protein yielded from NC and C HCV-HCC tissues decreased (31%, 67%) relative to control livers.