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Highlights • Supported liquid extraction is easy to use as visual phase separation isn't needed. • Automated sample preparation allows fast sample process and subsequent analysis. • Automated liquid handling coupled with LC-MS/MS as high-throughput method. • Washout gradient in LC method removes strongly retaining compounds from the column. • Sensitive method of 1.08/1.41 ng/ml for amodiaquine/desethylamodiaquine., Amodiaquine is a drug used for treatment of malaria and is often used in combination with artesunate in areas where malaria parasites are still susceptible to amodiaquine. Liquid chromatography tandem-mass spectrometry was used to quantify amodiaquine and its active metabolite, desethylamodiaquine, in plasma samples. A low sample volume of 100 µl, and high-throughput extraction technique using a supported liquid extraction (SLE+) technique on an automated liquid handler platform for faster sample processing are some of the advantages of this method. Separation of amodiaquine from desethylamodiaquine was achieved using a reversed phase Zorbax SB-CN 50 mm × 4.6 mm, I.D. 3.5 µm column with acetonitrile and 20 mM ammonium formate with 1% formic acid pH ~ 2.6 (15–85, v/v) as mobile phase. The absolute recoveries of amodiaquine and desethylamodiaquine were 66% to 76%, and their isotope label internal standard were in the range of 73% to 85%. Validation results of the developed method demonstrated intra-batch and inter-batch precisions within the acceptance criteria range of ± 15.0%. There were no matrix or carry-over effects observed. The lower limit of quantification was 1.08 ng/ml for amodiaquine and 1.41 ng/ml for desethylamodiaquine. The method showed robust and accurate performance with high sensitivity. Thus, the validated method was successfully implemented and applied in the evaluation of a clinical trial where participants received artemether–lumefantrine plus amodiaquine twice daily for three days (amodiaquine dose of 10 mg base/kg/day).

Zoptarelin doxorubicin is a fusion molecule of the chemotherapeutic doxorubicin and a luteinizing hormone-releasing hormone receptor (LHRHR) agonist, designed for drug targeting to LHRHR positive tumors. The aim of this study was to establish a physiologically based pharmacokinetic (PBPK) parent-metabolite model of zoptarelin doxorubicin and to apply it for drug–drug interaction (DDI) potential analysis. The PBPK model was built in a two-step procedure. First, a model for doxorubicin was developed, using clinical data of a doxorubicin study arm. Second, a parent-metabolite model for zoptarelin doxorubicin was built, using clinical data of three different zoptarelin doxorubicin studies with a dosing range of 10–267 mg/m2, integrating the established doxorubicin model. DDI parameters determined in vitro were implemented to predict the impact of zoptarelin doxorubicin on possible victim drugs. In vitro, zoptarelin doxorubicin inhibits the drug transporters organic anion-transporting polypeptide 1B3 (OATP1B3) and organic cation transporter 2 (OCT2). The model was applied to evaluate the in vivo inhibition of these transporters in a generic manner, predicting worst-case scenario decreases of 0.5% for OATP1B3 and of 2.5% for OCT2 transport rates. Specific DDI simulations using PBPK models of simvastatin (OATP1B3 substrate) and metformin (OCT2 substrate) predict no significant changes of the plasma concentrations of these two victim drugs during co-administration. The first whole-body PBPK model of zoptarelin doxorubicin and its active metabolite doxorubicin has been successfully established. Zoptarelin doxorubicin shows no potential for DDIs via OATP1B3 and OCT2.

Background: Curcuminoids, flavoring, and coloring agents in food have potent antioxidant, anti-tumor activity, and anti-inflammatory effects. However, they are rapidly metabolized to lesser active metabolites. Therefore, various studies have been conducted to synthesize new and stable curcumin analogues with enhanced therapeutic activity. Methods: Fluorinated curcumin compounds (2a-2f) were synthesized by Knoevenagel condensation between fluorobenzaldehydes (1a-1f) with curcumin. Fluorinated demethoxycurcumin (3a) was synthesized by condensation between demethoxycurcumin and 3,4-difluorobenzaldehyde (1f). The structures of these compounds were confirmed by FTIR, 1H-NMR, 13C-NMR, 19FNMR, and mass spectroscopy. Antiproliferative activities of these synthetic compounds were evaluated against breast cancer cells (4T1), melanoma cancer cells (B16F10), and normal cell lines (NIH 3T3) using MTT assay. The interaction of curcumin, 2f and 3a with several proteins (1HCL, 2ZOQ, 3D94, 5EW3, 4WA9, 1XKK, 6CCY) was investigated. The structural preservation of the epidermal growth factor receptor (EGFR) was investigated by molecular dynamics simulation. Results: The spectroscopic data obtained confirmed the proposed structure of fluorinated analogues. The results showed that compounds 2f and 3a inhibited cancer cells proliferation significantly more than other compounds. Compounds 2f and 3a showed the highest affinity and lowest binding energy with EGFR. The binding energies were -7.8, -10, and - 9.8 kcal/mol for curcumin, 2f and 3a with EGFR, respectively. The molecular docking results demonstrated that compounds 2f and 3a were firmly bound in a complex with EGFR via the formation of a hydrogen bond. Conclusion: In summary, we found that fluorinated demethoxycurcumin and fluorinated curcumin induces cancer cell death and binds to EGFR with high affinity.

Oxcarbazepine (OXZ) and levetiracetam (LEV) are two new generation anti‐epileptic drugs, often co‐administered in children with enzyme‐inducing antiepileptic drugs (EIAEDs). The anti‐epileptic effect of OXZ and LEV are linked to the exposure of OXZ’s active metabolite 10‐monohydroxy derivative (MHD) and (the parent) LEV, respectively. However, little is known about the confounding effect of age and EIAEDs on the pharmacokinetics (PKs) of MHD and LEV. To address this knowledge gap, physiologically‐based pharmacokinetic (PBPK) modeling was performed in the PK‐Sim software using literature data from children greater than or equal to 2 years of age. Age‐related changes in clearance (CL) of MHD and LEV were characterized, both in the presence (group 1) and absence (group 2) of concomitant EIAEDs. The drug‐drug interaction effect of EIAEDs was estimated as the difference in CL estimates between groups 1 and 2. PBPK modeling suggests that bodyweight normalized CL (ml/min/kg) is higher in younger children than their older counterparts (i.e., due to an influence of age). Concomitant EIAEDs further increase MHD’s CL to a fixed extent of 25% at any age, but EIAEDs’ effect on LEV’s CL increases with age from 20% (at 2 years) to 30% (at adolescence). Simulations with the maximum recommended doses (MRDs) revealed that children between 2 and 4 years and greater than 4 years, who are not on EIAEDs, are at risk of exceeding the reference exposure range for OXZ and LEV, respectively. This analysis demonstrates the use of PBPK modeling in understanding the confounding effect of age and comedications on PKs in children and adolescents.

PB2452, a neutralizing monoclonal antibody fragment that binds the antiplatelet drug ticagrelor with high affinity, is being developed as a ticagrelor reversal agent. To identify a clinically useful intravenous (i.v.) reversal regimen, a semimechanistic exposure‐response model was developed during the PB2452 first‐in‐human phase I study. From a randomized, double‐blind, placebo‐controlled, single‐dose trial to evaluate the safety, efficacy, and pharmacokinetics (PKs) of PB2452 in 61 healthy volunteers pretreated with ticagrelor, sequential dose cohort data were used to build and refine an exposure‐response model that combined population PK models for ticagrelor (TICA), ticagrelor active metabolite (TAM), and PB2452, and related their binding relationships to the PK of uncomplexed TICA and TAM which is predictive of platelet inhibition. Platelet function was assessed by multiple assays. The model was developed using Bayesian methods in NONMEM. Human PK and pharmacodynamic data from sequential dose cohorts were used to initially define and then refine model parameters. Model simulations indicated that an initial i.v. bolus of PB2452, followed by a high‐rate infusion, and then a slower‐rate infusion would provide immediate and sustained reversal of the antiplatelet effects of ticagrelor. Based on model predictions, a 6 g i.v. bolus followed by 6 g infused over 4 h and then 6 g over 12 h was identified and tested in study subjects and shown to provide complete reversal within 5 min of infusion onset that was sustained for 20–24 h. The model is predictive of the reversal profile of PB2452 and will inform future trials of PB2452.

Paeoniflorin-6'-O-benzene sulfonate (CP-25) is a novel ester derivative of paeoniflorin, which has been shown to have synergistic pharmacodynamic effects with leflunomide (LEF). To determine the effects of CP-25 on the pharmacokinetics of LEF in rats, we developed an UPLC-MS/MS-based method for the determination of levels of teriflunomide (TER, an active metabolite of LEF). This method was used to determine TER concentrations in the plasma, urine, feces, and bile, heart, liver, spleen, lung, kidney, intestinal, brain, and synovial tissues, and peripheral blood mononuclear cells (PBMCs) of rats in the control [LEF (10 mg/kg)] and combined [CP-25(50 mg/kg×7d) plus LEF (10 mg/kg)] groups. TER AUC, Tmax , MRT, t1/2α , and t1/2β were significantly lower and CL was significantly higher in the combined group than in the control group. Oral CP-25 administration in combination with LEF was found to promote TER excretion in urine, feces, and bile, and to reduce its contents in most tissues and organs, especially in the liver, which may reduce LEF-induced liver injury. CP-25 also increased TER exposure in the synovium and its absorption by PBMCs, and this could explain the synergistic effects of CP-25 and LEF.

Synthetic nucleoside or nucleotide analogues played a key role to the development of antiviral agents in past decades. However, low membrane permeability and insufficient cellular phosphorylation impaired the biological activity of polar nucleoside drugs because they have to penetrate the cell membrane and be phosphorylated to active metabolite stepwise by intracellular enzymes. To overcome these limitations, diverse lipophilic prodrug modifications based on nucleoside mono-, di-, and triphosphate were designed and put into practice to efficiently deliver nucleoside into the target site, and bypass the rate-limited phosphorylation step. As the most successful prodrug strategy, ProTide technology has led to the discovery of three FDA-approved antiviral agents, including sofosbuvir, tenofovir alafenadmide, and remdesivir, which has been authorized for emergency use in patients of COVID-19 in the US. In recent years, nucleoside di- and triphosphate prodrugs have also made the significant progress. This review will focus on the summary of design approach and metabolic activation path of different nucleotide prodrug strategies. The potential application of nucleotide prodrugs for the treatment of COVID-19 was also described due to the pandemic of SARS-CoV-2.

Context As an inhibitor cytochrome P450 family 2 subfamily C polypeptide 8 (CYP2C8), quercetin is a naturally occurring flavonoid with its glycosides consumed at least 100 mg per day in food. However, it is still unknown whether quercetin and selexipag interact. Objective The study investigated the effect of quercetin on the pharmacokinetics of selexipag and ACT-333679 in beagles. Materials and methods The ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to investigate the pharmacokinetics of orally administered selexipag (2 mg/kg) with and without quercetin (2 mg/kg/day for 7 days) pre-treatment in beagles. The effect of quercetin on the pharmacokinetics of selexipag and its potential mechanism was studied through the pharmacokinetic parameters. Results The assay method was validated for selexipag and ACT-333679, and the lower limit of quantification for both was 1 ng/mL. The recovery and the matrix effect of selexipag were 84.5–91.58% and 94.98–99.67%, while for ACT-333679 were 81.21–93.90% and 93.17–99.23%. The UPLC-MS/MS method was sensitive, accurate and precise, and had been applied to the herb-drug interaction study of quercetin with selexipag and ACT-333679. Treatment with quercetin led to an increased in Cmax and AUC0–t of selexipag by about 43.08% and 26.92%, respectively. While the ACT-333679 was about 11.11% and 18.87%, respectively. Discussion and conclusion The study indicated that quercetin could inhibit the metabolism of selexipag and ACT-333679 when co-administration. Therefore, the clinical dose of selexipag should be used with caution when co-administered with foods high in quercetin.

Background: Licorice is widely used as a hepatoprotective herb for thousands of years in Traditional Chinese Medicine, and its main chemical constituent glycyrrhizin (GL) is used as a treatment for chronic hepatitis in Japan for over 20 years. 18β-Glycyrrhetinic acid (GA) is the main active metabolite of GL. Objective: Series of GA derivatives were designed and synthesized, and their anti-HCV activities were screened to investigate structure-activity relationship (SAR). Besides, their in-silico ADMET properties were analyzed to search for promising lead compound for further identification of anti-HCV terpenoid candidate. Methods: GA derivatives were synthesized via reactions of oxidation, oxime, rearrangement, esterification and acylation, etc. In vitro anti-HCV activity of derivatives was tested on the HCV cell culture (HCVcc) system. In-silico ADMET properties analysis were performed via “pkCSM” and “SwissADME” platforms. Results: Eighteen GA derivatives were synthesized and their structures were confirmed by MS and NMR spectrums. All compounds exhibited superior HCV inhibitory activity to that of GA. Compound 2 possessed the most potent anti-HCV activity with IC50 value of 0.79 μM, which is nearly 58 times potent than SA (a previously reported potent anti-HCV terpenoids) and >200 times than GA. SAR revealed the introduction of 3-oxo, short-chain (C1-C3) aliphatic alcohols or cyclic aliphatic amines is conducive to improving anti-HCV activity. In-silico ADMET prediction demonstrated most of the potent compounds possessed favorable ADMET properties. Conclusion: Structural modification of GA at 3-position and 30-position is an effective approach to searching for potent anti-HCV agents. Compound 2, with the most potent anti-HCV activity and favorable in-silico ADMET properties, is a promising lead compound for further identification of anti-HCV terpenoid candidate.

Tetramethylpyrazine (TMP) is commonly used as an antiplatelet drug in clinic. However, the short half-life and low bioavailability limited its applications. 3, 5, 6-Trimethylpyrazine-2-carboxAylic acid (TMP-COOH) and 2-hydroxy-3, 5, 6-trimethylpyrazine (TMP-OH) are the two major active metabolites of TMP in vivo. Both displayed antiplatelet aggregation activity but have obvious disadvantage of rapid metabolism. In this study, conjugates of TMP-COOH/TMP-OH with amino acids were designed to address this issue. We demonstrated that 13 out of 20 conjugates displayed higher antiplatelet aggregation activity than TMP. The optimized compound 4a was further proved to reduce clot retraction, prolong the bleeding time, thrombin time, prothrombin time, activated partial thromboplatin time and reduce fibrinogen content. Taken together, we demonstrated the conjugation strategy could be exploited to develop TMP derivatives for antiplatelet agents.

Remdesivir (RDV) is the first drug approved by the US Food and Drug Administration (FDA) for the treatment of coronavirus disease 2019 (COVID-19) in certain patients requiring hospitalization. As a nucleoside analogue prodrug, RDV undergoes intracellular multistep activation to form its pharmacologically active species, GS-443902, which is not detectable in the plasma. A question arises that whether the observed plasma exposure of RDV and its metabolites would correlate with or be informative about the exposure of GS-443902 in tissues. A whole body physiologically-based pharmacokinetic (PBPK) modeling and simulation approach was utilized to elucidate the disposition mechanism of RDV and its metabolites in the lungs and liver and explore the relationship between plasma and tissue pharmacokinetics (PK) of RDV and its metabolites in healthy subjects. In addition, the potential alteration of plasma and tissue PK of RDV and its metabolites in patients with organ dysfunction was explored. Our simulation results indicated that intracellular exposure of GS-443902 was decreased in the liver and increased in the lungs in subjects with hepatic impairment relative to the subjects with normal liver function. In subjects with severe renal impairment, the exposure of GS-443902 in the liver was slightly increased, whereas the lung exposure of GS-443902 was not impacted. These predictions along with the organ impairment study results may be used to support decision making regarding the RDV dosage adjustment in these patient subgroups. The modeling exercise illustrated the potential of whole body PBPK modeling to aid in decision making for nucleotide analogue prodrugs, particularly when the active metabolite exposure in the target tissues is not available.

Made available in DSpace on 2022-04-29T08:35:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 The COVID-19 pandemic prompted the FDA to authorize a new nucleoside analogue, remdesivir, for emergency use in affected individuals. We examined the effects of its active metabolite, remdesivir triphosphate (RTP), on the activity of the replicative mitochondrial DNA polymerase, Pol γ. We found that while RTP is not incorporated by Pol γ into a nascent DNA strand, it remains associated with the enzyme impeding its synthetic activity and stimulating exonucleolysis. In spite of that, we found no evidence for deleterious effects of remdesivir treatment on the integrity of the mitochondrial genome in human cells in culture. Department of Chemistry Auburn University at Montgomery Department of Biochemistry and Molecular Biology Southern Illinois University School of Medicine Departamento de Tecnologia Faculdade de Ciências Agrárias e Veterinárias Universidade Estadual Paulista “Júlio de Mesquita Filho” Departamento de Tecnologia Faculdade de Ciências Agrárias e Veterinárias Universidade Estadual Paulista “Júlio de Mesquita Filho”

Introduction The O-[11C]methylated derivatives of the clinically used neprilysin inhibitor (NEPi) sacubitril ([11C]SacOMe, (2R,4S)-ethyl 5-([biphenyl]-4-yl)-4-(4-[11C]methoxy-4-oxobutanamido)-2-methylpentanoate) and LBQ657 ([11C]MeOLBQ, (2R,4S)-5-(biphenyl-4-yl)-4-[(3-carboxypropionyl)amino]-2-methylpentanoic acid [11C]methyl ester and [11C]LBQOMe, (2R,4S)-5-(biphenyl-4-yl)-4-[(4-[11C]methoxy-4-oxobutanamido)]-2-methylpentanoic acid) were evaluated to determine their potential as PET imaging tracers and investigate the effect of such labeling esterification on neprilysin (NEP) binding. Methods [11C]MeOLBQ, [11C]SacOMe and [11C]LBQOMe were synthesized by O-[11C]methylation using [11C]methyl triflate. Binding of these radiolabeled derivatives (5 nM) were assessed by autoradiography on rat neprilysin rich kidney slices with or without 10 μM NEPi (thiorphan or sacubitril) for 20 min at 37 °C. [11C]LBQOMe was further tested for binding selectivity in the presence of 10 μM of angiotensin-converting enzyme inhibitor (ACEi, captopril) or angiotensin II AT1 receptor blocker (AT1R, losartan). Radioligands were evaluated for their in vitro stability up to 20 min after incubation at 37 °C in rat and human plasma by reverse-phase column-switch HPLC. Non-radioactive SacOMe incubated in rat and human plasma was analyzed by HPLC-coupled with high resolution mass spectrometry (HRMS) to confirm the metabolites' identity. [11C]SacOMe main labeled metabolite was further analyzed by HPLC after incubation in rat kidney slices at 37 °C. Results The novel [11C]SacOMe and [11C]LBQOMe were produced in 32 ± 3% RCY and 15 ± 6% at EOS (decay-corrected from [11C]CO2, n = 3), high molar activity (407 ± 92 GBq/μmol and 260 ± 92 GBq/μmol), and high chemical (≥90%) and radiochemical (≥99%) purities in a total synthesis time of 31 and 34 min, respectively. High accumulation of [11C]SacOMe and [11C]LBQOMe in kidneys was completely blocked (>99.9%) by pre-incubation with NEPi, whereas [11C]MeOLBQ displayed negligible uptake in autoradiography studies. [11C]LBQOMe binding was not affected by saturating doses of losartan or captopril indicating binding selectivity for NEP. While [11C]SacOMe and [11C]LBQOMe were stable in human plasma (>92%) even after 20 min incubation at 37 °C, rat plasma analyses exhibited >95% biotransformation of [11C]SacOMe, 40% of [11C]LBQOMe and >80% loss of the 11C-methyl group of [11C]MeOLBQ after 5 min of incubation. Comparable results using the non-radioactive SacOMe were obtained by HPLC-HRMS. Radio-HPLC analysis of the extracted activity of rat kidney slices incubated with [11C]SacOMe demonstrated that >95% of the radioactive signal corresponded to [11C]LBQOMe as the main metabolite. Conclusion The desethyl active metabolite of [11C]SacOMe, [11C]LBQOMe, displayed stability in human plasma, binding selectivity for neprilysin over ACE or AT1R in rat kidney slices. Rapid plasmatic dealkylation at the 2-methylbutanoic acid position is in line with the necessity of incorporating the labeling group on oxobutanoic acid side in the strategy to develop a stable O-alkylated labeled derivative of sacubitril.

This study investigated the impact of polymorphisms of metabolic enzymes on plasma concentrations of cilostazol and its metabolites, and the influence of the plasma concentrations and polymorphisms on the cardiovascular side effects in 30 patients with cerebral infarction. Plasma concentrations of cilostazol and its active metabolites, and CYP3A5*3 and CYP2C19*2 and *3 genotypes were determined. The median plasma concentration/dose ratio of OPC-13213, an active metabolite by CYP3A5 and CYP2C19, was slightly higher and the median plasma concentration rate of cilostazol to OPC-13015, another active metabolite by CYP3A4, was significantly lower in CYP3A5*1 carriers than in *1 non-carriers (p = 0.082 and p = 0.002, respectively). The CYP2C19 genotype did not affect the pharmacokinetics of cilostazol. A correlation was observed between changes in pulse rate from the baseline and plasma concentrations of cilostazol (R = 0.539, p = 0.002), OPC-13015 (R = 0.396, p = 0.030) and OPC-13213 (R = 0.383, p = 0.037). A multiple regression model, consisting of factors of the plasma concentration of OPC-13015, levels of blood urea nitrogen, and pulse rate at the start of the therapy explained 55.5% of the interindividual variability of the changes in pulse rate. These results suggest that plasma concentrations of cilostazol and its metabolites are affected by CYP3A5 genotypes, and plasma concentration of OPC-13015, blood urea nitrogen, and pulse rate at the start of therapy may be predictive markers of cardiovascular side effects of cilostazol in patients with cerebral infarction.

Ciclesonide (CIC) is the first inhaled highly potent corticosteroid which does not cause any cortisol suppression. It has been developed for the treatment of asthma in human and more recently in equine. CIC is the active compound of Aservo® EquiHaler® (Boehringer Ingelheim Vetmedica GmbH), the pre-filled inhaler generating a medicated mist based on Soft MistTM technology. This prodrug is rapidly converted to desisobutyryl-ciclesonide (des-CIC), the main pharmacologically active compound. Due to its anti-inflammatory properties CIC is prohibited for use in horse competitions. To set up an appropriate control, the determination of detection times and screening limits are required. Therefore, a highly sensitive analytical method based on Supported Liquid Extraction (SLE) combined with Liquid Chromatography - High Resolution tandem Mass Spectrometry (LC-HRMS/MS) was developed to detect CIC and its active metabolite des-CIC in plasma. The lower limit of detection of CIC and des-CIC was approximately 1 pg/mL in plasma. After a pilot study conducted on a single horse at the recommended dose (8 actuations twice daily corresponding to 5.5 mg/day for the first five days, followed by 12 actuations once daily corresponding to 4.1 mg/day in the last five days), the same protocol was applied in the main study using six-horses. In all horses, CIC and des-CIC levels were less than 5 and 10 pg/mL, respectively, at 36 hours after the end of the administration. The outcome of this risk assessment study should be useful to draw any recommendations for horse competitions.

Introduction HS-10234, a novel prodrug of tenofovir (TFV), functions by inhibiting nucleotide reverse transcriptase against retroviral infections including hepatitis B virus and human immunodeficiency virus (HIV). As it is a possible substitute for TFV co-administration with emtricitabine, determining the drug-drug interactions (DDI) between HS-10234 and emtricitabine therapy will be helpful for researchers to design and conduct future phase II/III studies and merits careful examination in the era of evolving new combination antiretroviral therapy regimens. Methods We conducted an open-label, two-sequence, two-period, self-controlled phase I trial that enrolled 36 healthy volunteers randomized into two groups (group 1 and group 2). Eighteen subjects in group 1 were orally administered HS-10234 at a 25-mg daily dose for 7 days during period 1 (D1-D7) followed by co-administration of emtricitabine at a 200-mg dose once daily (QD) for 7 additional days during period 2 (D8-D14). Participants in group 2 were orally administered emtricitabine 200 mg QD for 7 days during period 1 (D1-D7) and then co-administered HS-10234 25 mg QD for 7 additional days during period 2 (D8-D14). Pharmacokinetics (PK) of HS-10234 and emtricitabine were characterized when administered alone and in combination. The concentrations of HS-10234 and its metabolites TFV and emtricitabine were determined using high performance liquid chromatography-mass spectrometry (HPLC-MS)/MS. Peripheral blood monocyte cells (PBMCs) were isolated for detection of intracellular concentrations of HS-10234's active metabolite, intracellular tenofovir diphosphate (TFV-DP) pre-dose and 2, 4, 8, 12 and 24 h post-dose on D7 and D14 in group 1. WinNonlin software was used to calculate PK parameters. Results After multiple-dose administration of HS-10234 with emtricitabine, the AUC0-tau of HS-10234 and TFV-DP was 1.327- and 1.403-fold higher than that with HS-10234 administration alone. The Cmax and AUC0-tau were increased 1.120- and 1.077-fold compared to emtricitabine administration alone. Co-administration of HS-10234 with oral emtricitabine was well tolerated. No serious adverse events were observed. Conclusions Although a slightly increased steady-state PK exposure of HS-10234 and TFV-DP was observed with co-administration of oral HS-10234 with emtricitabine, these changes were not considered clinically relevant. Thus, dose adjustments are not recommended for HS-10234 combination with emtricitabine. Trial registration NCT04477096, July 20, 2020.

Background and purpose Overweight or obese patients exhibit poorer platelet responses to clopidogrel; however, the mechanisms behind this phenotype remain to be elucidated. Here, we sought to dissect whether and why obesity could affect the metabolic activation of and/or platelet response to clopidogrel in obese patients and high-fat diet-induced obese mice. Experimental approach A post hoc stratified analysis of an observational clinical study was performed to investigate changes in residual platelet reactivity with increasing body weight in patients taking clopidogrel. Furthermore, high-fat diet-induced obese mice were used to reveal alterations in systemic exposure of clopidogrel thiol active metabolite H4, ADP-induced platelet activation and aggregation, the expression of genes responsible for the metabolic activation of clopidogrel, count of circulating reticulated and mature platelets, and proliferation profiles of megakaryocyte in bone marrow. The relevant genes and potential signaling pathways were predicted and enriched according to the GEO datasets available from obese patients. Key results Obese patients exhibited significantly attenuated antiplatelet effect of clopidogrel. In diet-induced obese mice, systemic exposure of clopidogrel active metabolite H4 was significantly reduced but that of its hydrolytic metabolite was increased due to down-regulation of certain P450s but up-regulation of Ces1 in the liver. Moreover, enhanced proliferation of megakaryocytes and elevated platelet count also contributed. Conclusion and implications Obesity attenuates metabolic activation of clopidogrel and increases counts of circulating reticulated and mature platelets, leading to impaired platelet responsiveness to the drug in mice, suggesting that clopidogrel dosage may need to be adjusted adequately in overweight or obese patients.

Aims Examine relationships between the systemic exposure of acalabrutinib, a highly selective, next-generation Bruton tyrosine kinase inhibitor, and its active metabolite (ACP-5862) vs. efficacy and safety responses in patients with B-cell malignancies who received acalabrutinib as monotherapy or in combination with obinutuzumab. Methods For exposure-efficacy analyses, patients with untreated chronic lymphocytic leukaemia were assessed for best overall response, progression-free survival and tumour regression. For exposure-safety analyses, incidences of grade ≥2 adverse events (AEs), grade ≥3 AEs and grade ≥2 events of clinical interest were assessed in patients with B-cell malignancies. Acalabrutinib and ACP-5862 pharmacokinetic (PK) parameter estimates were obtained from population PK modelling. Exposure calculations were based on study dosing regimens. Total active moieties were calculated to account for contributions of ACP-5862 to overall efficacy/safety. Results A total of 573 patients were included (exposure-efficacy analyses, n = 274; exposure-safety analyses, n = 573). Most patients (93%) received acalabrutinib 100 mg twice daily. Median total active area under the concentration-time curve (AUC24h,ss ) and total active maximal concentration at steady-state (Cmax,ss ) were similar for patients who received acalabrutinib as monotherapy or in combination with obinutuzumab, and for responders and nonresponders. No relationship was observed between AUC24h,ss /Cmax,ss and progression-free survival or tumour regression. Acalabrutinib AUC24h,ss and Cmax,ss were generally comparable across groups regardless of AE incidence. Conclusion No clinically meaningful correlations between acalabrutinib PK exposure and efficacy and safety outcomes were observed. These data support the fixed acalabrutinib dose of 100 mg twice daily in the treatment of patients with B-cell malignancies.

Background Dysregulation of histone deacetylases (HDACs) is common in cancer and is critical to the development and progression of the majority of tumors. This first-in-human Phase Ia study assessed the safety, efficacy, and pharmacokinetics (PK) of OBP-801, a cyclic depsipeptide class I HDAC inhibitor. Methods Adult patients with advanced solid tumors were treated in 3 dose cohorts (1.0 mg/m2, 2.0 mg/m2 or 2.8 mg/m2) of OBP-801 that was administered via intravenous infusion weekly. Initially, an accelerated titration design was used that was followed by a 3 + 3 dose escalation strategy. Primary objective was assessment of safety. Secondary objectives included determination of PK and objective response rate. Results Seventeen patients were enrolled, of which 8 patients were evaluable for efficacy. Drug-related ≥ Grade 3 treatment-emergent adverse events included abdominal pain, anemia, fatigue, gamma glutamyl-transferase increase, hypertriglyceridemia and vomiting. No dose-limiting toxicity was observed in the 1.0 mg/m2 cohort. The PK data showed that OBP-801 and its active metabolite OBP-801-SH exposure increased proportionally and more than proportionally, respectively. No accumulation of either agent was noticed after repeat administration. Best response was stable disease (37.5%), with one patient each in the three cohorts. Conclusion Further investigations of the OBP-801 1.0 mg/m2 dose will be needed to better understand the efficacy of the agent, either alone or in combination. Trial registration: NCT02414516 (ClinicalTrials.gov) registered on April 10, 2015.

High-dose radiation exposure results in hematopoietic and gastrointestinal acute radiation syndromes followed by delayed effects of acute radiation exposure, which encompasses multiple organs, including heart, kidney, and lung. Here we sought to further characterize the natural history of radiation-induced heart injury via determination of differential protein and metabolite expression in the heart. We quantitatively profiled the proteome and metabolome of left and right ventricle from non-human primates following 12 Gy partial body irradiation with 2.5% bone marrow sparing over a time period of 3 wk. Global proteome profiling identified more than 2,200 unique proteins, with 220 and 286 in the left and right ventricles, respectively, showing significant responses across at least three time points compared to baseline levels. High-throughput targeted metabolomics analyzed a total of 229 metabolites and metabolite combinations, with 18 and 22 in the left and right ventricles, respectively, showing significant responses compared to baseline levels. Bioinformatic analysis performed on metabolomic and proteomic data revealed pathways related to inflammation, energy metabolism, and myocardial remodeling were dysregulated. Additionally, we observed dysregulation of the retinoid homeostasis pathway, including significant post-radiation decreases in retinoic acid, an active metabolite of vitamin A. Significant differences between left and right ventricles in the pathology of radiation-induced injury were identified. This multi-omic study characterizes the natural history and molecular mechanisms of radiation-induced heart injury in NHP exposed to PBI with minimal bone marrow sparing.

Tramadol is an opioid medication used to treat moderately severe pain. CYP2D6 inhibition could be important for tramadol as it decreases the formation of its pharmacologically active metabolite, O-desmethyltramadol, potentially resulting in increased opioid use and misuse. The objective of this study was to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O-desmethyltramadol pharmacokinetics using quinidine and metoprolol as prototypical perpetrator drugs. A physiologically-based pharmacokinetic model for tramadol and O-desmethyltramadol was developed and verified in PK-Sim V8 and linked to respective models of quinidine and metoprolol to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O-desmethyltramadol exposure. Our results show that there is a differentiated impact of CYP2D6 inhibitors on tramadol and O-desmethyltramadol based on their mechanisms of inhibition. Following allosteric inhibition by a single dose of quinidine, the exposure of both tramadol (51% increase) and O-desmethyltramadol (52% decrease) was predicted to be significantly altered after concomitant administration of a single dose of tramadol. Following multiple-dose administration of tramadol and a single-dose or multiple-dose administration of quinidine, the inhibitory effect of quinidine was predicted to be long (∼42h) and to alter exposure of tramadol and O-desmethyltramadol by up to 60%, suggesting that co-administration of quinidine and tramadol should be avoided clinically. In comparison, there is no predicted significant impact of metoprolol on tramadol and O-desmethyltramadol exposure. In fact, tramadol is predicted to act as a CYP2D6 perpetrator and increase metoprolol exposure, which may necessitate the need for dose separation. This article is protected by copyright. All rights reserved.

Entrectinib (ROZLYTREK®) is a CNS-active, potent, and selective inhibitor of ROS1, TRK A/B/C, and ALK kinase activity. It was recently approved for the treatment of ROS1-positive non-small cell lung cancer and NTRK gene fusion-positive solid tumors. The main objective of this analysis was to characterize the pharmacokinetics (PK) of entrectinib and its main active metabolite, M5. A total of 276 cancer patients receiving oral entrectinib were included in the analysis. A model-based population approach was used to characterize the PK profiles of both entities using NONMEM® 7.4. A joint model captures the PK of both entrectinib and M5. The effects of pH modifiers, formulation, weight, age, and sex on model parameters were assessed. Model performance was evaluated using visual predictive checks (VPCs). The absorption of entrectinib was best described using a sequential zero- and first-order absorption model and the disposition with one-compartment model for each entity with linear elimination. Moderate-to-high between-patient variability was estimated in model parameters (from 30.8% for the apparent clearance of entrectinib to 122% for the first-order absorption rate constant). Theory-based allometric scaling using body weight on clearances and volumes and a 28% lower relative bioavailability of the F1 formulation in pediatric patients were retained in the model. The VPC confirmed the good predictive performance of the PopPK model. A robust population PK model was built and qualified for entrectinib and M5, describing linear PK for both entities. This model was used to support the ROZLYTREK® new drug application.

Per the well-known resistance of hepatitis B virus to nucleoside/nucleotide analogs, alternative treatment options with higher resistance barriers have been approved for use in both treatment-naïve and lamivudine-resistant hepatitis B virus infections. This phase I study was conducted in adults with normal and impaired renal function to evaluate the effect of renal impairment on the pharmacokinetics of besifovir, a prodrug of an acyclic nucleotide phosphonate, that is mainly cleared via renal excretion. An open-label, single-dose parallel-group clinical study was conducted in subjects with normal renal function and mild, moderate, and severe renal impairment. Subjects received a single oral dose of besifovir dipivoxil 150 mg, and serial blood and urine samples were collected for up to 72 hours after dosing to assess the pharmacokinetic characteristics of besifovir. The extent of plasma exposure of besifovir, detected as its major and active metabolites, LB80331 and LB80317, respectively, increased with worsening renal function. Compared to the subjects with normal renal function, the mean areas under the concentration-time curves of LB80331 increased by 1.5-, 2.5-, and 4.5-fold in subjects with mild, moderate, and severe impairment, respectively. LB80317 showed a 1.8-, 3.2-, and 6.2-fold increase in subjects with mild, moderate, and severe renal impairment compared to those with normal function. The ratios of LB80331 renal clearance and the average estimated glomerular filtration rate of each renal impairment group with respect to the normal group were similar. The increase in plasma exposure and decrease in renal clearance suggest the need to adjust dosage regimens in patients with moderate to severe renal impairment.

Equilibrative nucleoside transporters (ENTs) are present at the blood-testis barrier (BTB), where they can facilitate antiviral drug disposition to eliminate a sanctuary site for viruses detectable in semen. The purpose of this study was to investigate ENT-drug interactions with three nucleoside analogs, remdesivir, molnupiravir, and molnupiravir’s active metabolite, β-d-N(4)-hydroxycytidine (EIDD-1931), and four non-nucleoside molecules repurposed as antivirals for coronavirus disease 2019 (COVID-19). The study used three-dimensional pharmacophores for ENT1 and ENT2 substrates and inhibitors and Bayesian machine learning models to identify potential interactions with these transporters. In vitro transport experiments demonstrated that remdesivir was the most potent inhibitor of ENT-mediated [(3)H]uridine uptake (ENT1 IC(50): 39 μM; ENT2 IC(50): 77 μM), followed by EIDD-1931 (ENT1 IC(50): 259 μM; ENT2 IC(50): 467 μM), whereas molnupiravir was a modest inhibitor (ENT1 IC(50): 701 μM; ENT2 IC(50): 851 μM). Other proposed antivirals failed to inhibit ENT-mediated [(3)H]uridine uptake below 1 mM. Remdesivir accumulation decreased in the presence of 6-S-[(4-nitrophenyl)methyl]-6-thioinosine (NBMPR) by 30% in ENT1 cells (P = 0.0248) and 27% in ENT2 cells (P = 0.0054). EIDD-1931 accumulation decreased in the presence of NBMPR by 77% in ENT1 cells (P = 0.0463) and by 64% in ENT2 cells (P = 0.0132), which supported computational predictions that both are ENT substrates that may be important for efficacy against COVID-19. NBMPR failed to decrease molnupiravir uptake, suggesting that ENT interaction is likely inhibitory. Our combined computational and in vitro data can be used to identify additional ENT-drug interactions to improve our understanding of drugs that can circumvent the BTB. SIGNIFICANCE STATEMENT: This study identified remdesivir and EIDD-1931 as substrates of equilibrative nucleoside transporters 1 and 2. This provides a potential mechanism for uptake of these drugs into cells and may be important for antiviral potential in the testes and other tissues expressing these transporters.