Dose finding for ZSP1601 in patients with nonalcoholic steatohepatitis using population pharmacokinetics and exposure-response approach.

INTRODUCTION: ZSP1601 is a novel pan-phosphodiesterase inhibitor developed in China specifically for the treatment of nonalcoholic fatty liver disease (NAFLD). AIM: The aim is to develop a population pharmacokinetic (pop PK) model for ZSP1601 by integrating data from two clinical studies. This undertaking aims to deepen our understanding of the clinical factors that influence ZSP1601 exposure while simultaneously investigating exposure-response (ER) relationships related to efficacy and safety. The goal is to guide formulating optimal dosage strategies in the subsequent phases of clinical trials. METHODS: Analysis of pooled concentration-time data from 95 subjects, with 2647 observations from two clinical trials involving healthy volunteers and NAFLD patients, employed a nonlinear mixed-effects modeling approach to characterize ZSP1601 pharmacokinetics. Covariate impact on ZSP1601 pharmacokinetics was investigated, and relationships between ZSP1601 exposure, efficacy and safety endpoints were explored. RESULTS: A two-compartment model featuring sequential zero-order then first-order absorption and first-order elimination effectively described ZSP1601's pharmacokinetic profile. Covariate analyses identified body weight as a statistically significant factor affecting drug central volume, while FED (food consumption) influenced absorption rate constant and duration. The Sigmoid Emax model aptly captured exposure-response relationships for ALT (alanine aminotransferase), AST (aspartate aminotransferase), and LFC (liver fat content) percentage changes relative to baseline and ZSP1601 exposure levels (AUCss) on the 29th day. ZSP1601 exposure levels (Cmax1) exhibited a significant exposure-response relationship with headaches (p < 0.001). CONCLUSION: The PopPK model and ER analysis, based on available data, comprehensively characterizes ZSP1601's pharmacokinetic, safety and efficacy profile, aiding informed decisions regarding dosage selection for the drug's complete developmental trajectory. The exposure-response (ER) analysis yields quantitative insights into the optimal balance of efficacy and safety within different dosage regimens for patient administration. In light of these findings, the dose regimen of 100 mg administered twice daily is proposed for subsequent clinical investigations.

Discovery of baloxavir sodium as a novel anti-CCHFV inhibitor: Biological evaluation of in vitro and in vivo.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic bunyavirus with a fatality rate of up to 40%. Currently, there are no licensed antiviral drugs for the treatment of CCHF; thus, the World Health Organization (WHO) listed the disease as a priority. A unique viral transcription initiation mechanism called "cap-snatching" is shared by influenza viruses and bunyaviruses. Thus, we tested whether baloxavir (an FDA-approved anti-influenza drug that targets the "cap-snatching" mechanism) could inhibit CCHFV infection. In cell culture, baloxavir acid effectively inhibited CCHFV infection and targeted CCHFV RNA transcription/replication. However, it has weak oral bioavailability. Baloxavir marboxil (the oral prodrug of baloxavir) failed to protect mice against a lethal dose challenge of CCHFV. To solve this problem, baloxavir sodium was synthesized owing to its enhanced aqueous solubility and pharmacokinetic properties. It consistently and significantly improved survival rates and decreased tissue viral loads. This study identified baloxavir sodium as a novel scaffold structure and mechanism of anti-CCHF compound, providing a promising new strategy for clinical treatment of CCHF after further optimization.

Design, Synthesis, Formulation, and Bioevaluation of Trisubstituted Triazines as Highly Selective mTOR Inhibitors for the Treatment of Human Breast Cancer.

The aberrant activation of the PI3K/mTOR signaling pathway is implicated in various human cancers. Thus, the development of inhibitors targeting mTOR has attracted considerable attention. In this study, we used a structure-based drug design strategy to discover a highly potent and kinase-selective mTOR inhibitor 24 (PT-88), which demonstrated an mTOR inhibitory IC50 value of 1.2 nM without obvious inhibition against another 195 kinases from the kinase profiling screening. PT-88 displayed selective inhibition against MCF-7 cells (IC50: 0.74 µM) with high biosafety against normal cells, in which autophagy induced by mTOR inhibition was implicated. After successful encapsulation in a lipodisc formulation, PT-88 demonstrated favorable pharmacokinetic and biosafety profiles and exerted a large antitumor effect in an MCF-7 subcutaneous bearing nude mice model. Our study shows the discovery of a highly selective mTOR inhibitor using a structure-based drug discovery strategy and provides a promising antitumor candidate for future study and development.

Dose-dependent effect of lamotrigine on quetiapine serum concentration in patients using instant release tablets.

PURPOSE: Lamotrigine was previously reported to reduce serum concentration of quetiapine. The aim of this study was to investigate whether lamotrigine dose or quetiapine formulation was of importance for the drug interaction. METHODS: Patients combining lamotrigine with quetiapine (cases) were included retrospectively from a routine therapeutic drug monitoring (TDM) service, as were a control group of patients using quetiapine without any interacting drugs. The case and control groups were divided into groups using immediate release (IR) and extended release (XR) quetiapine. The case group was further split into high-dose (> 200 mg/day) and low-dose (≤ 200 mg/day) lamotrigine users. Quetiapine concentration-to-dose (C/D) ratio and metabolite-to-parent ratio (MPR) were compared between the control group and dose-separated case groups using ANOVA test and t-tests. RESULTS: In total, 406 patients were included. The mean C/D ratio of IR quetiapine was 46% lower in the high-dose lamotrigine group compared with the control group (P < 0.001), while no interaction effect was present in the low dose lamotrigine group (P = 0.7). Regardless of lamotrigine dose, there was no difference in quetiapine C/D ratio for patients using the XR formulation (P = 0.4). The quetiapine MPR was unaffected regardless of formulation and lamotrigine dose (P ≥ 0.06). CONCLUSION: The effect of lamotrigine in reducing quetiapine concentration is only significant for patients using quetiapine IR tablets who are treated with lamotrigine doses > 200 mg/day. Because of high variability in the interaction effect, TDM of quetiapine should be recommended during co-prescription of high-dose lamotrigine.

Safety, Tolerability, and Pharmacokinetics of the Novel Antiviral Agent Ensitrelvir Fumaric Acid, a SARS-CoV-2 3CL Protease Inhibitor, in Healthy Adults.

Ensitrelvir is a novel selective inhibitor of the 3C-like protease of SARS-CoV-2, which is essential for viral replication. This phase 1 study of ensitrelvir assessed its safety, tolerability, and pharmacokinetics of single (part 1, n = 50) and multiple (part 2, n = 33) ascending oral doses. Effect of food on the pharmacokinetics of ensitrelvir, differences in pharmacokinetics of ensitrelvir between Japanese and white participants, and effect of ensitrelvir on the pharmacokinetics of midazolam (a cytochrome P450 3A [CYP3A] substrate) were also assessed. In part 1, Japanese participants were randomized to placebo or ensitrelvir at doses of 20, 70, 250, 500, 1,000, or 2,000 mg. In part 2, Japanese and white participants were randomized to placebo or once-daily ensitrelvir at loading/maintenance dose 375/125 mg or 750/250 mg for 5 days. Most treatment-related adverse events observed were mild in severity and were resolved without treatment. Plasma exposures showed almost dose proportionality, and geometric mean half-life of ensitrelvir following the single dose was 42.2 to 48.1 h. Food intake reduced Cmax and delayed Tmax of ensitrelvir but did not impact the area under the curve (AUC), suggesting suitability for administration without food restriction. Compared with Japanese participants, plasma exposures were slightly lower for white participants. Ensitrelvir affected the pharmacokinetics of CYP3A substrates because of increase in AUC of midazolam coadministered with ensitrelvir 750/250 mg on day 6. In conclusion, ensitrelvir was well-tolerated and demonstrated favorable pharmacokinetics, including a long half-life, supporting once-daily oral dosing. These results validate further assessments of ensitrelvir in participants with SARS-CoV-2 infection.

A Pharmacokinetics-Time to Alleviation of Symptoms Model to Support Extrapolation of Baloxavir Marboxil Clinical Efficacy in Different Ethnic Groups with Influenza A or B.

Baloxavir marboxil, the prodrug of baloxavir acid, is an anti-influenza antiviral. Here, a pharmacokinetics-time to alleviation of symptoms (PK-TTAS) model was developed and used to (I) characterize the PK-TTAS relationship, (II) quantify the impact of covariates, and (III) predict TTAS in different ethnic groups. Data from 1781 otherwise-healthy (OwH) or high-risk (HR) patients included in phase II (JapicCTI-153090) and III studies (NCT02954354 and NCT02949011) were used; patients received either placebo or oral baloxavir marboxil. The natural distribution of TTAS in placebo-treated patients was modeled, then TTAS data from the baloxavir marboxil arms were added to model the impact of baloxavir acid concentration on TTAS. PK parameters estimated by a population PK model and informed by phase I data (NCT03959332 and KCT0003535) were included to simulate TTAS in Chinese and South Korean patients. Composite symptom score at baseline (TSS0), ethnicity, sex, and patient type (OwH or HR) significantly impacted the natural TTAS distribution. TTAS reduced with increasing baloxavir acid concentrations. Compared with placebo, high and low baloxavir acid exposures (AUC0-inf 5.13-16.65 and 0.72-5.13 µg.hr/mL, respectively) significantly reduced TTAS; no covariates affected the drug effect on TTAS. Simulated TTAS was similar between OwH or HR Chinese, South Korean, and other Asian patients, with median reductions from placebo between 18.3-18.8 hours and 21.2-22.0 hours in OwH and HR patients, respectively, assuming TSS0 > 10. Ethnicity (Asian vs. non-Asian) did not significantly impact the drug effect on TTAS; predicted TTAS was similar across different Asian populations. This suggests Chinese and South Korean patients may benefit from similar efficacy as other Asian patients.

Plasma concentrations of diclazuril following oral administration of diclazuril and diclazuril sodium salt to cattle.

Diclazuril is a triazine-based antiprotozoal agent widely used in veterinary practice that may have clinical application in the treatment of bovine protozoal diseases. The present study reports on the bioavailability, pharmacokinetics, and metabolism of diclazuril and diclazuril sodium salt in cattle following administration of diclazuril suspended in water and by direct application of diclazuril sodium salt to the oral mucosa. Compared with diclazuril itself, the sodium salt formulation of diclazuril applied to the oral mucosa was rapidly and reliably absorbed. Plasma concentrations of diclazuril peaked at around 8 h after oral-mucosal administration of diclazuril sodium salt. On the contrary, application of diclazuril itself orally resulted in delayed and variable absorption. The mean bioavailability of diclazuril as pure powder was 42.5% relative to diclazuril sodium salt indicating approximately 2.5-fold increase in bioavailability of diclazuril as a sodium salt relative to diclazuril as a pure compound in cattle. The present study also reports finding of a previously unreported diclazuril metabolite at high concentrations in plasma especially after oral administration of diclazuril. Further studies, including synthesis and characterization of the novel described metabolite, are required to accurately determine aspects of the metabolism of diclazuril in cattle.

Pharmacokinetics of orally administered single-dose ponazuril in cats.

Cats and kittens in animal shelters and catteries regularly suffer from severe gastrointestinal coccidiosis, which can be fatal, and there are no drugs labeled for feline coccidiosis in the United States. Ponazuril, a triazine-class drug, is increasingly used at a dose of 50 mg/kg/d, orally, for three to five days in shelter environments for coccidiosis. A single oral dose of ponazuril paste 15% (Marquis® ; Merial) at 50 mg/kg was administered to six healthy adult cats. Sample analysis was completed via high-performance liquid chromatography. Plasma concentrations peaked at 7.49 ± 2.06 µg/ml at 14.67 ± 7.45 hr post-administration. This study shows that ponazuril achieved a plasma concentration that inhibits growth of similar organisms after a single oral dose in cats. Further studies are necessary to optimize dosing for the treatment of clinical coccidiosis in cats.

Safety and efficacy of avapritinib in advanced systemic mastocytosis: the phase 1 EXPLORER trial.

Advanced systemic mastocytosis (AdvSM) is a rare hematologic neoplasm driven by the KIT D816V mutation and associated with poor survival. This phase 1 study ( NCT02561988 ) evaluated avapritinib (BLU-285), a selective KIT D816V inhibitor, in patients with AdvSM. The primary endpoints were the maximum tolerated dose, recommended phase 2 dose and safety of avapritinib. Secondary endpoints included overall response rate and changes in measures of mast cell burden. Avapritinib was evaluated at doses of 30-400 mg once daily in 86 patients, 69 with centrally confirmed AdvSM. Maximum tolerated dose was not reached, and 200 mg and 300 mg daily were studied in dose-expansion cohorts. The most frequent adverse events observed were periorbital edema (69%), anemia (55%), diarrhea (45%), thrombocytopenia (44%) and nausea (44%). Intracranial bleeding occurred in 13% overall, but in only 1% of patients without severe thrombocytopenia (platelets <50 × 109/l). In 53 response-evaluable patients, the overall response rate was 75%. The complete remission rate was 36%. Avapritinib elicited ≥50% reductions in marrow mast cells and serum tryptase in 92% and 99% of patients, respectively. Avapritinib induced deep and durable responses, including molecular remission of KIT D816V in patients with AdvSM, and was well tolerated at the recommended phase 2 dose of 200 mg daily.

Absorption and Distribution of Toltrazuril and Toltrazuril Sulfone in Plasma, Intestinal Tissues and Content of Piglets after Oral or Intramuscular Administration.

Piglet coccidiosis due to Cystoisospora suis is a major cause of diarrhea and poor growth worldwide. It can effectively be controlled by application of toltrazuril (TZ), and oral formulations have been licensed for many years. Recently, the first parenteral formulation containing TZ in combination with iron (gleptoferron) was registered in the EU for the prevention of coccidiosis and iron deficiency anemia, conditions in suckling piglets requiring routine preventive measures. This study evaluated the absorption and distribution of TZ and its main metabolite, toltrazuril sulfone (TZ-SO2), in blood and intestinal tissues after single oral (20 mg/kg) or single intramuscular (45 mg/piglet) application of TZ. Fifty-six piglets were randomly allocated to the two treatment groups. Animals were sacrificed 1-, 5-, 13-, and 24-days post-treatment and TZ and TZ-SO2 levels were determined in blood, jejunal tissue, ileal tissue, and mixed jejunal and ileal content (IC) by high performance liquid chromatography (HPLC). Intramuscular application resulted in significantly higher and more sustained concentrations of both compounds in plasma, intestinal tissue, and IC. Higher concentrations after oral dosing were only observed one day after application of TZ in jejunum and IC. Toltrazuril was quickly metabolized to TZ-SO2 with maximum concentrations on day 13 for both applications. Remarkably, TZ and TZ-SO2 accumulated in the jejunum, the primary predilection site of C. suis, independently of the administration route, which is key to their antiparasitic effect.

Synthesis and Biological Evaluation of Novel Triazine Derivatives as Positive Allosteric Modulators of α7 Nicotinic Acetylcholine Receptors.

Enhancing neuronal α7 nicotinic acetylcholine receptor (α7 nAChR) function can alleviate cognitive deficits. Here, we report the design, synthesis, and evaluation of N-(4-(trifluoromethoxy)phenyl)-1,3,5-triazin-2-amine derivatives 8-10 as a series of novel α7 nAChR positive allosteric modulators (PAMs). The representative compound 10e functions as a type I PAM with an EC50 of 3.0 µM and approximately 38-fold enhancement of α7 current in the presence of agonist acetylcholine (100 µM). It specifically enhances α7 current with high selectivity. Compound 10e shows good pharmacokinetic property in mice. Intraperitoneal injection of 10e (3 mg/kg) exhibits sufficient blood-brain barrier penetration in mice. Furthermore, 10e can also rescue the auditory gating deficit in mice with schizophrenia-like behavior. Molecular docking of 10e with homopentameric α7 nAChR reveals a new mode of action. These results support the potential of 10e for treatment for schizophrenia and Alzheimer's disease.

Chloro-s-triazines-toxicokinetic, Toxicodynamic, Human Exposure, and Regulatory Considerations.

Chloro-s-triazines-atrazine, cyanazine, propazine, simazine, and terbuthylazine-are structurally similar herbicides, differing only in specific s-triazine4-and 6-N alkyl substituents. It is generally regarded that their toxicokinetics, such as, metabolic pathways, biological effects and toxicities, also share more similar features than the differences. Consequently, it is useful to compare their characteristics to potentially find useful structure-activity relationships or other similarities or differences regarding different active compounds, their metabolites, and biological effects including toxic outcomes. The ultimate goal of these exercises is to apply the summarized knowledge-as far as it is possible regarding a patchy and often inadequate database-to cross the in vitro-in vivo and animal-human borders and integrate the available data to enhance toxicological risk assessment for the benefit of humans and ecosystems.

Bioanalytical RP-HPLC method for the determination of ponazuril in plasma.

The goal of this investigation was to establish a reliable technique for the quantitation of ponazuril in limited sample volumes. Samples were extracted with chloroform and separation was achieved with a Symmetry RP18 column. Ultraviolet absorption was measured at 254 nm. A combination of 0.1% formic acid and acetonitrile (50:50) was used as the mobile phase. The calibration curve was linear from 0.1-25 µg/mL, with a lower limit of quantification of 0.1 µg/mL with a 100 µL sample. The precision and accuracy were well within the range set by the Food and Drug Administration and the recovery was over 95%. This technique was used to analyze ponazuril samples and found to be appropriate for pharmacokinetic studies.

PHARMACOKINETICS OF A SINGLE ORAL DOSE OF PONAZURIL IN THE INDIAN PEAFOWL (PAVO CRISTATUS).

Ponazuril, a novel coccidiocidal triazinetrione, has shown promise in addressing apicomplexan diseases in mammals and birds. This study describes the pharmacokinetics of ponazuril in healthy adult Indian peafowl (Pavo cristatus) following a single oral dose administered at two different dosages. Peafowl (four males and four females) were administered compounded ponazuril at 20 or 40 mg/kg orally in a double crossover design, with a 2-wk washout period. Blood was collected from each bird at 2, 4, 8, 24, 48, 72, 96, and 120 h after administration for plasma concentration of ponazuril using high-pressure liquid chromatography. Fecals were evaluated for coccidial shedding for 3 consecutive d prior to the ponazuril trial, 1 wk after the first dose of ponazuril, and 1 wk after the second dose of the trial. After the first trial, one peafowl administered 20 mg/kg ponazuril was shedding coccidia, but no coccidia were detected by the end of the second trial. Ponazuril reached peak concentrations (Tmax) at 21.38 h + 5.25 and 22.04 h + 7.39, and peak concentration (Cmax) were 11.82 µg/ml + 3.01 and 18.42 µg/ml + 4.13, for 20 and 40 mg/kg doses, respectively. Ponazuril was detected at 120 h with a concentration of 9.48 µg/ml + 2.59 and 12.25 µg/ml + 2.89 and a half-life of 219.4 + 58.7 h and 186.7 + 58.7 h, for and 40 mg/kg doses, respectively. Ponazuril in peafowl was well absorbed orally, plasma concentrations increased with dose, and elimination was slower than current dosages for birds would suggest. No obvious adverse effects were observed at either dosage.

Simulation of Remdesivir Pharmacokinetics and Its Drug Interactions.

PURPOSE: Remdesivir, a drug originally developed against Ebola virus, is currently recommended for patients hospitalized with coronavirus disease of 2019 (COVID-19). In spite of United States Food and Drug Administration's recent assent of remdesivir as the only approved agent for COVID-19, there is limited information available about the physicochemical, metabolism, transport, pharmacokinetic (PK), and drug-drug interaction (DDI) properties of this drug. The objective of this in silico simulation work was to simulate the biopharmaceutical and DDI behavior of remdesivir and characterize remdesivir PK properties in special populations which are highly affected by COVID-19. METHODS: The Spatial Data File format structures of remdesivir prodrug (GS-5734) and nucleoside core (GS-441524) were obtained from the PubChem database to upload into the GastroPlus software 9.8 version (Simulations Plus Inc., USA). The Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) Predictor and PKPlus modules of GastroPlus were used to simulate physicochemical and PK properties, respectively, in healthy and predisposed patients. Physiologically based pharmacokinetic (PBPK) modeling of GastroPlus was used to simulate different patient populations based on age, weight, liver function, and renal function status. Subsequently, these data were used in the Drug-Drug Interaction module to simulate drug interaction potential of remdesivir with other COVID-19 drug regimens and with agents used for comorbidities. RESULTS: Remdesivir nucleoside core (GS-441524) is more hydrophilic than the inactive prodrug (GS-5734) with nucleoside core demonstrating better water solubility. GS-5734, but not GS-441524, is predicted to be metabolized by CYP3A4. Remdesivir is bioavailable and its clearance is achieved through hepatic and renal routes. Differential effects of renal function, liver function, weight, or age were observed on the PK profile of remdesivir. DDI simulation study of remdesivir with perpetrator drugs for comorbidities indicate that carbamazepine, phenytoin, amiodarone, voriconazole, diltiazem, and verapamil have the potential for strong interactions with victim remdesivir, whereas agents used for COVID-19 treatment such as chloroquine and ritonavir can cause weak and strong interactions, respectively, with remdesivir. CONCLUSIONS: GS-5734 (inactive prodrug) appears to be a superior remdesivir derivative due to its hepatic stability, optimum hydrophilic/lipophilic balance, and disposition properties. Remdesivir disposition can potentially be affected by different physiological and pathological conditions, and by drug interactions from COVID-19 drug regimens and agents used for comorbidities.

Constructing slow-release formulations of herbicide metribuzin using its co-extrusion with biodegradable polyester poly-ε-caprolactone.

Different technologies to prepare long term pesticide forms include polymer coating, preparing composites and encapsulating pesticides in nanoparticles. A simple and low-cost method was proposed to obtain slow-release formulations by co-extrusion of a pesticide with a biodegradable polymer at a temperature above the melting points of both components. A herbicide metribuzin and low-melting polyester poly-ε-caprolactone were chosen for this work. Formulations containing 10%, 20%, and 40% herbicide were prepared. During 7 days of their exposition in water, it was released from 81% to 96% of initially loaded metribuzin; the highest release was detected for 40%-loaded forms. Biodegradation of the constructs and pesticide release were further studied in the model soil. Degradation rates of the specimens increased with an increase in pesticide content, from 9% to 20% over 14 weeks for the 10%/20%-loaded and the 40%-loaded specimens, respectively. The release of metribuzin reached, respectively, 37-38% and 55%. The herbicide content in soil was lower due to its partial degradation in soil; it reached 23-25% and 33%, respectively, from initially loaded into the polymer matrix. Release kinetics of metribuzin in water as in soil best fitted the First-order model. The used approach is promising for obtaining long-term release formulations for soil applications.

Safety and pharmacokinetic interaction between fotagliptin, a dipeptidyl peptidase-4 inhibitor, and metformin in healthy subjects.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors have significant clinical efficacy for type 2 diabetes mellitus (T2DM). The combination of fotagliptin (FOT) with metformin (MET) is a promising therapeutic approach in MET-resistant patients. The aim of the present study was to evaluate the pharmacokinetic (PK) interaction between FOT and MET in healthy subjects after multiple-dose administration. METHODS: Eighteen participants received a randomized open-label, three period treatment that included MET 1000 mg alone, co-administration of FOT 24 mg and MET, followed by FOT 24 mg alone. Serial blood samples were collected for PK analysis, which included geometric mean ratios (GMRs) with 90% confidence intervals (CIs), area under the concentration-time curve (AUC), and maximum plasma concentration (Cmax). RESULTS: Analysis results showed that for FOT alone or combination therapy, the 90% CIs of the GMR for AUC0-24,ss and Cmax,ss were 102.08% (98.9%, 105.36%) and 110.65% (102.19%, 119.82%), respectively. For MET, they were 113.41% (100.32%, 128.22%) and 97.11% (83.80%, 112.55%) for AUC0-12,ss and Cmax,ss, respectively. FOT or MET monotherapy and the combination therapy with both drugs were well tolerated. CONCLUSIONS: No PK drug-drug interactions were found in the combination therapy with FOT and MET. Therefore, FOT can be co-administered with MET without dose adjustment. TRIAL REGISTRATION: The trial is registered at http://www.chinadrugtrials.org.cn/(Registration No. CTR20190221).

Discovery of Potent and Fast-Acting Antimalarial Bis-1,2,4-triazines.

Novel 3,3'-disubstituted-5,5'-bi(1,2,4-triazine) compounds with potent in vitro activity against Plasmodium falciparum parasites were recently discovered. To improve the pharmacokinetic properties of the triazine derivatives, a new structure-activity relationship (SAR) investigation was initiated with a focus on enhancing the metabolic stability of lead compounds. These efforts led to the identification of second-generation highly potent antimalarial bis-triazines, exemplified by triazine 23, which exhibited significantly improved in vitro metabolic stability (8 and 42 µL/min/mg protein in human and mouse liver microsomes). The disubstituted triazine dimer 23 was also observed to suppress parasitemia in the Peters 4-day test with a mean ED50 value of 1.85 mg/kg/day and exhibited a fast-killing profile, revealing a new class of orally available antimalarial compounds of considerable interest.

UPLC-MS/MS for the Herb-Drug Interactions of Xiao-Ai-Ping Injection on Enasidenib in Rats Based on Pharmacokinetics.

OBJECTIVE: To develop and validate a sensitive and rapid ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of enasidenib in rat plasma and to investigate the effect of Xiao-ai-ping injection (XAPI) on the pharmacokinetics of enasidenib in rats. METHODS: The rat plasma was precipitated with acetonitrile, enasidenib and internal standard (IS) were separated on an Acquity UPLC BEH C18 column, and acetonitrile and 0.1% formic acid were used as the mobile phase in gradient mode. Enasidenib and IS were monitored and detected by multiple reaction monitoring (MRM) using tandem mass spectrometry in positive ion mode. 12 Sprague-Dawley (SD) rats were randomly divided into control group (group A) and experimental group (group B), 6 rats in each group. Group B was intramuscularly injected with XAPI (0.3 mL/kg) every morning, 7 days in a row. Group A was intramuscularly injected with normal saline, 7 days in a row. On the seventh day, enasidenib (10 mg/kg) was given to both groups 30 min after injection of normal saline (group A) or XAPI (group B), and the blood was collected at different time points such as 0.33, 0.67, 1, 1.5, 2, 3, 4, 6, 9, 12, 24, and 48 h. The concentration of enasidenib was detected by UPLC-MS/MS, and the main parameters of pharmacokinetic of enasidenib were calculated using the DAS 2.0 software. RESULTS: Under the current experimental conditions, this UPLC method showed good linearity in the detection of enasidenib. Interday and intraday precision did not exceed 10%, the range of accuracy values were from -1.43% to 2.76%. The results of matrix effect, extraction recovery, and stability met the requirements of FDA approval guidelines of bioanalytical method validation. The C max of enasidenib in the group A and the group B was (458.87 ± 136.02) ng/mL and (661.47 ± 107.32) ng/mL, t 1/2 was (7.74 ± 0.91) h and (8.64 ± 0.42) h, AUC(0 - t) was (4067.24 ± 1214.36) ng·h/mL and (5645.40 ± 1046.30) ng·h/mL, AUC(0 - ∞) was (4125.79 ± 1235.91) ng·h/mL and (5759.61 ± 1078.59) ng·h/mL, respectively. The C max of enasidenib in group B was 44.15% higher than that in group A, and the AUC(0 - t) and AUC(0 - ∞) of enasidenib in group B were 38.80% and 39.60% higher than that in group A, respectively, and the t 1/2 was prolonged from 7.74 h to 8.64 h. CONCLUSION: An UPLC-MS/MS method for the determination of enasidenib in rat plasma was established. XAPI can inhibit the metabolism of enasidenib and increase the concentration of enasidenib in rats. It is suggested that when XAPI was combined with enasidenib, the herb-drug interaction and adverse reactions should be paid attention to, and the dosage should be adjusted if necessary.

Hemoadsorption eliminates remdesivir from the circulation: Implications for the treatment of COVID-19.

Both antiviral treatment with remdesivir and hemoadsorption using a CytoSorb® adsorption device are applied in the treatment of severe COVID-19. The CytoSorb® adsorber consists of porous polymer beads that adsorb a broad range of molecules, including cytokines but also several therapeutic drugs. In this study, we evaluated whether remdesivir and its main active metabolite GS-441524 would be adsorbed by CytoSorb® . Serum containing remdesivir or GS-441524 was circulated in a custom-made system containing a CytoSorb® device. Concentrations of remdesivir and GS-441524 before and after the adsorber were analyzed by liquid chromatography-tandem mass spectrometry. Measurements of remdesivir in the outgoing tube after the adsorber indicated almost complete removal of remdesivir by the device. In the reservoir, concentration of remdesivir showed an exponential decay and was not longer detectable after 60 mins. GS-441524 showed a similar exponential decay but, unlike remdesivir, it reached an adsorption-desorption equilibrium at ~48 µg/L. Remdesivir and its main active metabolite GS-441524 are rapidly eliminated from the perfusate by the CytoSorb® adsorber device in vitro. This should be considered in patients for whom both therapies are indicated, and simultaneous application should be avoided. In general, plasma levels of therapeutic drugs should be closely monitored under concurrent CytoSorb® therapy.