Cmax Values Research Articles

Effective in vitro evaluation of the risk of histamine release related to valemetostat tosylate using MRGPRX2-expressing cells.

Mas-related G-protein-coupled receptor X2 (MRGPRX2), expressed on mast cells, is associated with drug-induced pseudo-allergic reactions. Although it is well known that there are differences of sensitivity between species in the pseudo-allergic reactions, no platform for evaluating a human risk of the pseudo-allergic reactions observed in nonclinical studies has been established. Valemetostat tosylate, developed as an anti-cancer drug, induced histamine release in a nonclinical study with dogs. The purpose of the current study was to identify the mechanism and assess the human risk of valemetostat-tosylate-induced histamine release using dog and human MRGPRX2-expressing cells. In an experiment with human or dog MRGPRX2-expressing cells, valemetostat tosylate caused activation of human and dog MRGPRX2. Importantly, the EC50 for dog MRGPRX2 was consistent with the Cmax value at which histamine release was observed in dogs. Furthermore, the EC50 for human MRGPRX2 was ca. 27-fold higher than that for dog MRGPRX2, indicating a species difference in histamine-releasing activity. In a clinical trial, histamine release was not observed in patients receiving valemetostat tosylate. In conclusion, an in vitro assay using human and animal MRGPRX2-expressing cells would be an effective platform to investigate the mechanism and predict the human risk of histamine release observed in nonclinical studies.

Therapeutic Drug Monitoring of Linezolid in Drug-Resistant Tuberculosis Patients: Clinical Factors and Hematological Toxicities.

Previous studies have indicated that the development of severe adverse events is associated with linezolid peak concentration (Cmax), but the factors affecting linezolid Cmax and evidences on therapeutic drug monitoring to anticipate toxicity in drug-resistant tuberculosis (DR-TB) patients have not been clarified clearly. This study aimed to explore the factors influencing linezolid Cmax and investigate the association between linezolid concentration and hematological toxicity. This study included patients with drug-resistant tuberculosis treated with linezolid from January 2022 to September 2023. We analyzed the factors affecting linezolid Cmax using chi-squared and binary logistic regression. The diagnostic utility of linezolid Cmax in predicting hematological toxicity was evaluated using receiver operating characteristic (ROC) analysis. A total of 76 patients were enrolled in the study. 63.20% met the standard rates for linezolid Cmax. Age (P=0.036), weight (P=0.0016), and creatinine clearance (P=0.0223) significantly correlated with the Cmax. Hematological toxicity was observed in 46.05% (35/76) of patients, characterized by thrombocytopenia (31.58%, 24/76), anemia (6.58%, 5/76), and leukopenia (21.05%, 16/76). ROC curve analysis confirmed the predictive value of linezolid Cmax for thrombocytopenia with an area under curve of 0.728. Suboptimal linezolid Cmax was prevalent among patients with DR-TB, with age, weight, and renal function emerging as influential factors. Elevated linezolid Cmax increases the risk of thrombocytopenia. Meticulous monitoring of linezolid Cmax is imperative during anti-DR-TB therapy to tailor treatment and mitigate hematological toxicity.

Pharmacokinetic Analysis of Prognostic Factors in Patients With Advanced-Stage Intrahepatic Cholangiocarcinoma Following the Administration of Capsule Formulation of the Standardized Extract of Atractylodes lancea (Thunb) DC.

A statistical model is essential in determining the appropriate predictive indicators for therapies in many types of cancers. Predictors have been compared favorably to the traditional systems for many cancers. Thus, this study has been proposed as a new standard approach. A recent study on the clinical efficacy of Atractylodes lancea (Thunb) DC. (AL) revealed the higher clinical benefits in patients with advanced-stage intrahepatic cholangiocarcinoma (ICC) treated with AL compared with standard supportive care. We investigated the relationships between clinical efficacy and pharmacokinetic parameters of serum bioactivity of AL and its active constituent atractylodin and determined therapeutic ranges. Group 1 of advanced-stage ICC patients received daily doses of 1000 mg of standardized extract of the capsule formulation of AL (CMC-AL) for 90 days. Group 2 received daily doses of 1000 mg of CMC-AL for 14 days, followed by 1500 mg for 14 days, and 2000 mg for 62 days. Group 3 (control group) received palliative care. Cox proportional hazard model and Receiver Operating Characteristic (ROC) were applied to determine the cut-off values of AUC0-inf, Cmax, and Cavg associated with therapeutic outcomes. Number needed to treat (NNT) and relative risk (RR) were also applied to determine potential predictors. The AUC0-inf of total AL bioactivity of >96.71 µg hour/ml was identified as a promising predictor of disease prognosis, that is, progression-free survival (PFS) and disease control rate (DCR). Cmax of total AL bioactivity of >21.42 was identified as a predictor of the prognosis of survival. The therapeutic range of total AL bioactivity for PFS and DCR is 14.48 to 65.8 µg/ml, and for overall survival is 10.97 to 65.8 µg/ml. Conclusions: The predictors of ICC disease prognosis were established based on the pharmacokinetics of total AL bioactivity. The information could be exploited to improve the clinical efficacy of AL in patients with advanced-stage ICC. These predictors will be validated in a phase 2B clinical study. TCTR20210129007 (TCTR: www.clinicaltrials.in.th).

Phase I dose-escalation study to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of an inhaled recombinant human ACE2.

APN01 is a soluble recombinant human angiotensin-converting enzyme 2 (rhACE2), a key player in the renin-aldosterone-angiotensin system (RAAS). In clinical studies, APN01 was administered intravenously only, so far. The aim of this study (ClinicalTrials.gov: NCT05065645) was to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of inhaled APN01. This was a phase I, double-blind, placebo-controlled, dose-escalation study. Inhalation was conducted via a nebuliser over 15 min in three single ascending dose (SAD) cohorts (n=24) and two multiple ascending dose (MAD) cohorts (n=16: every 12 h for 7 days). Doses in the SAD cohort were 1.25, 2.5 and 5 mg·mL-1; doses in the MAD cohort were 2.5 and 5 mg·mL-1. Safety (including adverse events (AEs), laboratory findings and lung function results), PK and PD data were assessed. In the SAD and MAD cohorts, treatment-related AEs were slightly more frequent in the active treatment group than in the placebo group. AEs were mild to moderate, with no dose-limiting toxicities. No clinically relevant changes in lung function and laboratory results were observed. The mean maximum observed plasma concentration (Cmax) values after single and multiple doses of 5 mg·mL-1 APN01 were 1.88 and 6.61 ng·mL-1, respectively. Among the PD variables, significance was found for ACE2 and angiotensin 1-5. The application of aerosolised APN01 is safe and well tolerated after single and multiple doses. By achieving a high local concentration in the lungs and low systemic bioavailability, inhaled rhACE2 may present a therapeutic option in ACE2-related diseases.

ABCG2 polymorphism and rivaroxaban pharmacokinetics in healthy individuals after a single dose.

Rivaroxaban is a direct factor Xa inhibitor. Its interindividual variability is large and may be connected to the occurrence of adverse drug reactions or drug inefficacy. Pharmacogenetics studies concentrating on the reasons underlying rivaroxaban's inadequate response could help explain the differences in treatment results and medication safety profiles. Against this background, this study evaluated whether polymorphisms in the gene encoding the ABCG2 transporter modify the pharmacokinetic characteristics of rivaroxaban. A total of 117 healthy volunteers participated in two bioequivalence experiments with a single oral dose of 20 mg rivaroxaban, with one group fasting and the other being fed. Ultra-high-performance liquid chromatography coupled with mass spectrometry was employed to determine the plasma concentrations of rivaroxaban, and the WinNonlin program was used to calculate the pharmacokinetics parameters. In the fasting group, the rivaroxaban pharmacokinetic parameters of Vd (508.27 vs 334.45 vs 275.59 L) and t1/2 (41.04 vs 16.43 vs 15.47 h) were significantly higher in ABCG2 421 A/A genotype carriers than in ABCG2 421 C/C and 421 C/A genotype carriers (P<0.05). The mean values of Cmax (145.81 vs 176.27 vs 190.19 ng/mL), AUC0-t (1193.81 vs 1374.69 vs 1570.77 ng/mL·h), and Cl (11.82 vs 14.50 vs 13.01 mL/h) for these groups were lower, but this difference was not statistically significant (P>0.05). These findings suggested that the ABCG2 421 A/A genotype may impact rivaroxaban parameters after a single dose in healthy subjects. This finding must be validated before it is applied in clinical practice.

Development and validation of PBPK models for genistein and daidzein for use in a next-generation risk assessment.

All cosmetic ingredients must be evaluated for their safety to consumers. In the absence of in vivo data, systemic concentrations of ingredients can be predicted using Physiologically based Pharmacokinetic (PBPK) models. However, more examples are needed to demonstrate how they can be validated and applied in Next-Generation Risk Assessments (NGRA) of cosmetic ingredients. We used a bottom-up approach to develop human PBPK models for genistein and daidzein for a read-across NGRA, whereby genistein was the source chemical for the target chemical, daidzein. An oral rat PBPK model for genistein was built using PK-Sim® and in vitro ADME input data. This formed the basis of the daidzein oral rat PBPK model, for which chemical-specific input parameters were used. Rat PBPK models were then converted to human models using human-specific physiological parameters and human in vitro ADME data. In vitro skin metabolism and penetration data were used to build the dermal module to represent the major route of exposure to cosmetics. The initial oral rat model for genistein was qualified since it predicted values within 2-fold of measured in vivo PK values. This was used to predict plasma concentrations from the in vivo NOAEL for genistein to set test concentrations in bioassays. Intrinsic hepatic clearance and unbound fractions in plasma were identified as sensitive parameters impacting the predicted Cmax values. Sensitivity and uncertainty analyses indicated the developed PBPK models had a moderate level of confidence. An important aspect of the development of the dermal module was the implementation of first-pass metabolism, which was extensive for both chemicals. The final human PBPK model for daidzein was used to convert the in vitro PoD of 33nM (from an estrogen receptor transactivation assay) to an external dose of 0.2% in a body lotion formulation. PBPK models for genistein and daidzein were developed as a central component of an NGRA read-across case study. This will help to gain regulatory confidence in the use of PBPK models, especially for cosmetic ingredients.

Microemulsion co-delivering curcumin and DHA-rich algal oil alleviates nonalcoholic fatty liver disease

The combined effect of curcumin and docosahexaenoic acid (DHA) on liver injury has not yet been reported. We determined the synergistic effect of curcumin and DHA on the protection of WRL-68 cells from palmitic acid-induced injury, and on the inhibition of LX2 cells. A microemulsion to co-deliver both compounds was prepared by ultrasonic emulsification. Mice were fed a high-fat diet for 10 weeks to induce mild non-alcoholic fatty liver disease (NAFLD). At a dose of 5 mg/kg curcumin and 30 mg/kg DHA, the microemulsion successfully lowered serum triacylglycerol (TG) and low-density lipoprotein cholesterol levels, and significantly attenuated NAFLD. A pharmacokinetic study in rats showed that the microemulsion had a higher Cmax value for curcumin, a greater AUC0–24 value and a longer t1/2 value for both curcumin and DHA. This investigation provides a novel application of a combination of functional food ingredients to treat chronic liver disease.

Intestinal P-gp activity is reduced in postmenopausal women under breast cancer therapy.

Intestinal P-glycoprotein (P-gp) activity plays a crucial role in modulating the oral bioavailability of its substrates. Fexofenadine has commonly been used as a P-gp probe, although it is important to note the involvement of other drug transporters like, OATP1B1, OATP1B3, and OATP2B1. Invitro studies demonstrated an upregulation of P-gp protein in response to exposure to pregnancy-related hormones. The objective of this study was to investigate how intestinal P-gp activity is impacted by menopausal status. This study sampled fexofenadine plasma concentrations over 0-12 h after probe drug administration from two groups of patients with breast cancer: premenopausal (n = 20) and postmenopausal (n = 20). Fexofenadine plasma concentrations were quantified using liquid-chromatography tandem mass spectrometry. Area under the plasma concentration-time curve from zero to infinity (AUCinf ) was calculated through limited sampling strategies equation. Multiple linear regression was applied on AUCinf , maximum plasma concentration (Cmax ), and time to Cmax . Postmenopausal patients showed a significant increase in Cmax (geometric mean and 95% confidence interval [CI] 143.54, 110.95-176.13 vs. 223.54 ng/mL, 161.02-286.06 and in AUCinf 685.55, 534.98-878.50 vs. 933.54 ng·h/mL 735.45-1184.99) compared to premenopausal patients. The carriers of the ABCB1 3435 allele T displayed higher Cmax values of 166.59 (95% CI: 129.44-214.39) compared to the wild type at 147.47 ng/mL (95% CI: 111.91-194.34, p = 0.02). In postmenopausal individuals, the decrease in P-gp activity of ~40% may lead to an increased plasma exposure of orally administered P-gp substrates.

Impact of the PK/PD Approach in Therapeutic Drug Monitoring of Gentamicin

Gentamicin, a commonly used hospital aminoglycoside, exhibits a narrow therapeutic index, necessitating careful administration to prevent serious adverse effects. Our study aimed to assess the impact of Therapeutic drug Monitoring (TDM) by integrating Minimum Inhibitory Concentration (MIC) to customize dosage based on bacterial sensitivity. This was prospective study, conducted on a sample of 35 adult patients hospitalized in three university hospital centers in Eastern Algeria. Included patients underwent Therapeutic Drug Monitoring (TDM) of gentamicin based on the determination of Maximum concentration (Cmax), considering the determination of the MIC and achieving a Cmax/CMI ratio ≥ 8 to 10. Pharmaceutical interventions were suggested to clinicians to improve patient care. The mean age of our patients was 51.66 ± 16.72 years. All patients had Cmax values below the therapeutic range. Pathogenic microorganisms were identified in 64% of cases, and only two patients achieved the Cmax/CMI target of 8 to 10 prior to our interventions. In 41% of cases, clinicians heeded our guidance on regular therapeutic monitoring and dose adjustments. The therapeutic target was achieved in 66.6% of cases, with a Cmax/CMI target attainment rate of 44.4%.The use of individualized initial doses of gentamicin, combined with Therapeutic Drug Monitoring based on PK/PD parameters, enhances the chances of therapeutic success and restricts the emergence of bacterial resistance.

Physiologically based pharmacokinetic (PBPK) modeling of pitavastatin in relation to SLCO1B1 genetic polymorphism.

Pitavastatin, a potent 3-hydroxymethylglutaryl coenzyme A reductase inhibitor, is indicated for the treatment of hypercholesterolemia and mixed dyslipidemia. Hepatic uptake of pitavastatin is predominantly occupied by the organic anion transporting polypeptide 1B1 (OATP1B1) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene, whichis a polymorphic gene that encodes OATP1B1. SLCO1B1 genetic polymorphism significantly alters the pharmacokinetics of pitavastatin. This study aimed to establish the physiologically based pharmacokinetic(PBPK) model to predict pitavastatin pharmacokinetics according to SLCO1B1 genetic polymorphism. PK-Sim® version 10.0 was used to establish the whole-body PBPK model of pitavastatin. Our pharmacogenomic data and a total of 27 clinical pharmacokinetic data with different dose administration and demographic properties were used to develop and validate the model, respectively. Physicochemical properties and disposition characteristics of pitavastatin were acquired from previously reported data or optimized to capture the plasma concentration-time profiles in different SLCO1B1 diplotypes. Model evaluation was performed by comparing the predicted pharmacokinetic parameters and profiles to the observed data. Predicted plasma concentration-time profiles were visually similar to the observed profiles in the non-genotyped populations and different SLCO1B1 diplotypes. All fold error values for AUC and Cmax were included in the two fold range of observed values. Thus, the PBPK model of pitavastatin in different SLCO1B1 diplotypes was properly established. The present study can be useful to individualize the dose administration strategy of pitavastatin in individuals with various ages, races, and SLCO1B1 diplotypes.

Mixing energy as an adjustment tool for aerodynamic behaviour of an inhaled product: In-vitro and in-vivo effects

This paper describes the development of a fixed dose dry powder combination of indacaterol maleate (Inda) and glycopyrronium bromide (Glyco) in Easyhaler® inhaler for a comparative pharmacokinetic (PK) study, as well as the outcome of such a study. The development aim was to produce formulations with three different in vitro dispersibility profiles for both Inda and Glyco. This so-called ‘rake’ approach allows for quantitation of the candidate formulations relative to the reference product Ultibro® Breezhaler® in terms of the key PK parameters.Three formulations (A, B and C) were produced based on the mixing energy concept. For both APIs, formulation A (lowest mixing energy) displayed the highest fine particle fractions and formulation C (highest mixing energy) the lowest. GMP manufacturing confirmed the performance of the three formulations.The candidate formulations were tested against the reference product in a single dose PK study in healthy volunteers. Clear differences in Inda plasma concentration profiles were observed between the treatments when administered concomitantly with charcoal, with Easyhaler A showing the highest Cmax value and Easyhaler C the lowest. Easyhaler B was bioequivalent to Ultibro Breezhaler with regard to the primary PK parameters of Inda, Cmax and AUC72h. For Glyco, Easyhaler formulations A, B and C provided lower peak concentrations than Ultibro Breezhaler. For AUC72h of Glyco, Easyhaler B was bioequivalent to the reference product. Additional measures for adjustment of formulation performance can be foreseen, whose effects can be predicted based on mixing energy theory.

PBPK modeling to predict the pharmacokinetics of pantoprazole in different CYP2C19 genotypes.

Pantoprazole is used to treat gastroesophageal reflux disease (GERD), maintain healing of erosive esophagitis (EE), and control symptoms related to Zollinger-Ellison syndrome (ZES). Pantoprazole is mainly metabolized bycytochrome P450 (CYP)2C19, converting to 4'-demethyl pantoprazole. CYP2C19 is a genetically polymorphic enzyme, and the genetic polymorphism affects the pharmacokinetics and/or pharmacodynamics of pantoprazole. In this study, we aimed to establish the physiologically based pharmacokinetic (PBPK) model to predict the pharmacokinetics of pantoprazole in populations with various CYP2C19 metabolic activities. A comprehensive investigation of previous reports and drug databases was conducted to collect the clinical pharmacogenomic data, physicochemical data, and disposition properties of pantoprazole, and the collected data were used for model establishment. The model was evaluated by comparing the predicted plasma concentration-time profiles and/or pharmacokinetic parameters (AUC and Cmax) with the clinical observation results. The predicted plasma concentration-time profiles in different CYP2C19 phenotypes properly captured the observed profiles. All fold error values for AUC and Cmax were included in the two-fold range. Consequently, the minimal PBPK model for pantoprazole related to CYP2C19 genetic polymorphism was properly established and it can predict the pharmacokinetics of pantoprazole in different CYP2C19 phenotypes. The present model can broaden the insight into the individualized pharmacotherapy for pantoprazole.

Dose proportionality and bioavailability of quinoxaline-based JNK inhibitor after single oral and intravenous administration in rats

The dose proportionality and bioavailability of the potential anti-inflammatory and neuroprotective JNK inhibitor 11H-indeno[1,2-b]quinoxalin-11-one oxime (IQ-1) were evaluated by comparing pharmacokinetic parameters after single oral (25, 50 and 100 mg/kg) and intravenous (1 mg/kg) IQ-1 administration in rats. IQ-1 and its major metabolite ketone 11H-indeno[1,2-b]quinoxalin-11-one (IQ-18) were isolated from plasma samples by liquid–liquid extraction. IQ-1 (E-isomer) and IQ-18 were simultaneously quantified in plasma by the validated method of liquid chromatography with triple quadrupole mass spectrometry (HPLC–MS/MS). The absolute bioavailability of IQ-1 was < 1.5%. C max values were 24.72 ± 4.30, 25.66 ± 7.11 and 37.61 ± 3.53 ng/mL after single oral administration of IQ-1 at doses of 25, 50 and 100 mg/kg, respectively. IQ-1 exhibited dose proportionality at 50–100 mg/kg dose levels, whereas its pharmacokinetics was not dose proportional over the range of 25–50 mg/kg. IQ-18 demonstrated the invariance of the dose-normalized Cmax. In this study we systematically elucidated the absorption characteristics of IQ-1 in rat gastrointestinal tract and provided better understanding of IQ-1 pharmacology for the future development of a new formulations and therapeutic optimisation.

Evaluating the pharmacokinetic parameters of a single dose of oral disintegrating tablets in elderly patients with hypertension and hyperlipidemia

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, particularly in underprivileged areas such as Pakistan. Hypertension and hyperlipidemia are major risk factors for CVDs and often require medication for effective management. This study aimed to develop and validate a high-performance liquid chromatography (HPLC) method to assess the bioavailability of orally disintegrating tablets (ODTs) of atenolol and atorvastatin in elderly volunteers with high blood pressure and cholesterol levels by comparing the pharmacokinetic parameters of these ODTs with those of conventional tablet formulations. The study was conducted in Sargodha, Punjab Province, Pakistan, by recruiting 30 male and female elderly volunteers aged 45-65 years and weighing 60-90 kilograms. Each participant was administered a single dose of atenolol (25 mg), atorvastatin (10 mg), or an ODT containing both drugs. Blood samples were collected at specific intervals up to 48 hours postadministration. The concentrations of atenolol, atorvastatin, and the ODTs were measured using HPLC, and various pharmacokinetic parameters, including the area under the curve (AUC), maximum plasma concentration (Cmax), and elimination half-life (t½), were analyzed. The maximum concentration (Cmax) of 10 mg atorvastatin occurred at 4 hours (9.50 ng/mL), while for 25 mg atenolol, it peaked at 4 hours (150.00 ng/mL). The ODTs showed comparable pharmacokinetic profiles, with the Cmax values for atorvastatin and atenolol at 4 hours being 4.00 ng/mL and 165.00 ng/mL, respectively. The elimination half-life (t½) for the ODTs was 4.62 hours for atorvastatin and 4.95 hours for atenolol. The pharmacokinetic analysis indicated that the AUC and Cmax of the ODTs met the bioequivalence criteria, demonstrating absorption and elimination properties similar to those of conventional tablet formulations. The study concluded that the pharmacokinetic parameters of the ODT formulations atenolol and atorvastatin are comparable to those of conventional tablets. ODTs offer a viable and effective alternative for delivering these medications, particularly for patients who have difficulty swallowing pills, thereby potentially improving patient compliance.

Comparative Pharmacokinetics and Bioequivalence of Pour-On Ivermectin Formulations in Korean Hanwoo Cattle.

This study aimed to conduct a bioequivalence study of applying three pour-on ivermectin formulations at a dose of 1 mg/kg on the back of Korean native beef cattle (Hanwoo). To conduct bioequivalence testing, the pharmacokinetics of three groups (control Innovator, test Generic A, and test Generic B) of five clinically healthy Korean Hanwoo cattle (average weight 500 kg) were studied. After topical application to the skin, blood samples were drawn at the indicated times. These blood samples were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The time required to reach the maximum concentration (Tmax), the maximum concentration (Cmax), and the area under the curve (AUClast) of each pharmacokinetic parameter were compared for bioequivalence. The results showed that the control had a Tmax of 41 ± 1.24 h, a Cmax of 0.11 ± 0.01 μg/mL, and an AUClast of 9.33 ± 0 h*μg/mL). The comparator Generic A had a Tmax of 40 ± 1.14 h, a Cmax of 0.10 ± 0.01 (μg/mL, and an AUClast of 9.41 ± 0.57 h*μg/mL, while Generic B had a Tmax of 40 ± 2.21 h, a Cmax of 0.10 ± 0.01 μg/mL, and an AUClast of 9 h*μg/mL. The values of the bioequivalence indicators Cmax, Tmax, and AUC were all within the range of 80% to 120%, confirming that all three tested formulations were bioequivalent. In conclusion, the study showed that the two generic products were bioequivalent to the original product in Hanwoo cattle.

Effect of albumin substitution on pharmacokinetics of piperacillin/tazobactam in patients with severe burn injury admitted to the ICU.

Pathophysiological changes in severely burned patients alter the pharmacokinetics (PK) of anti-infective agents, potentially leading to subtherapeutic concentrations at the target site. Albumin supplementation, to support fluid resuscitation, may affect pharmacokinetic properties by binding drugs. This study aimed to investigate the PK of piperacillin/tazobactam in burn patients admitted to the ICU before and after albumin substitution as total and unbound concentrations in plasma. Patients admitted to the ICU and scheduled for 4.5 g piperacillin/tazobactam administration and 200 mL of 20% albumin substitution as part of clinical routine were included. Patients underwent IV microdialysis, and simultaneous arterial plasma sampling, at baseline and multiple timepoints after drug administration. PK analysis of total and unbound drug concentrations under steady-state conditions was performed before and after albumin supplementation. A total of seven patients with second- to third-degree burns involving 20%-60% of the total body surface were enrolled. Mean (SD) AUC0-8 (h·mg/L) of total piperacillin/tazobactam before and after albumin substitution were 402.1 (242)/53.2 (27) and 521.8 (363)/59.7 (32), respectively. Unbound mean AUC0-8 before and after albumin supplementation were 398.9 (204)/54.5 (25) and 456.4 (439)/64.5 (82), respectively. Albumin supplementation had little impact on the PK of piperacillin/tazobactam. After albumin supplementation, there was a numerical increase in mean AUC0-8 of total and unbound piperacillin/tazobactam, whereas similar Cmax values were observed. Future studies may investigate the effect of albumin supplementation on drugs with a higher plasma protein binding.

Abstract C045: Combinations of PI3K inhibitors with targeted oncology agents in multicellular spheroid models

Abstract Dysregulation of the phosphatidylinositol 3-kinase (PI3K) pathway plays a significant role in cancer, and inhibitors offer a promising strategy for targeted therapies. The selectivity of current inhibitors varies against different PI3K isoforms or subtypes. For example, alpelisib and inavolisib predominantly target the α-isoform, whereas duvelisib targets the δ- and γ-isoforms. By contrast, copanlisib is a pan-PI3K inhibitor, exhibiting activity against all isoforms. In combinations with other targeted agents, we investigated the activity of these four PI3K inhibitors against multicellular spheroids. The multicellular spheroids, grown from 60% malignant cells, 25% endothelial cells, and 15% mesenchymal stem cells, served as a model for human solid tumors that incorporates both malignant and stromal components. Thirty multicellular spheroid models were grown from various malignant cell types, including twenty-seven patient-derived cancer cell lines obtained from the NCI Patient-Derived Models Repository (https://pdmr.cancer.gov/) and three established cell lines from the NCI-60 human tumor cell line panel. After three days of spheroid growth, anticancer agents were introduced at concentrations up to their reported clinical Cmax value, if known. After seven days of drug exposure, cell viability was measured using the CellTiter-Glo 3D assay. Among the various drug combinations evaluated, simultaneous targeting of the PI3K and RAS pathways was highly effective, particularly against malignant cell lines with an activated RAS pathway. Notably, additive and/or synergistic activities were observed when either the α-isoform-specific PI3K inhibitors (alpelisib and inavolisib) or the pan-PI3K inhibitor (copanlisib) was combined with either the MEK inhibitor selumetinib, the ERK inhibitor ravoxertinib, or the type II pan-RAF kinase inhibitor DAY101. Additionally, combinations of the same three PI3K inhibitors with variant-specific inhibitors, such as vemurafenib (BRAF V600E), sotorasib (KRAS G12C), or MTRX-1133 (KRAS G12D) demonstrated selective activity against cell lines carrying the variant. Another effective combination with PI3K inhibitors was achieved with vertical inhibition of the PI3K pathway through the addition of the mTORC1/2 kinase inhibitor sapanisertib. Finally, combinations of a CDK4/6 inhibitor (abemaciclib or palbociclib) with a PI3K inhibitor demonstrated synergistic activities, although they were not as potent as other combinations. This project was funded in part with federal funds from the NCI, NIH, under contract no. HHSN261201500003I. Citation Format: Thomas S Dexheimer, Thomas Silvers, Nathan P Coussens, Rabih Said, Beverly A Teicher, James H Doroshow. Combinations of PI3K inhibitors with targeted oncology agents in multicellular spheroid models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C045.

Pharmacokinetic study of five components of Fuzheng Huayu tablets in healthy human plasma.

Natural medicines play a crucial role in clinical drug applications, serving as a primary traditional Chinese medicine for the clinical treatment of liver fibrosis. Understanding the in vivo metabolic process of the Fuzheng Huayu (FZHY) formula is essential for delving into its material basis and mechanism. In recent years, there has been a growing body of research focused on the mechanisms and component analysis of FZHY. This study aimed to examine the pharmacokinetics of FZHY in healthy volunteers following oral administration. Blood samples were collected at designated time intervals after the oral intake of 9.6-g FZHY tablets. A UHPLC-Q/Exactive method was developed to assess the plasma concentrations of five components post-FZHY ingestion. The peak time for all components occurred within 10 min. The peak concentration (Cmax ) values for amygdalin, schisandrin, and schisandrin A ranged from 3.47 to 28.80 ng/mL, with corresponding AUC(0-t) values ranging from 10.63 to 103.20 ng h/mL. For schisandrin B and prunasin, Cmax values were in the range of 86.52 to 229.10 ng/mL, and their AUC(0-t) values ranged from 375.26 to 1875.54 ng h/mL, indicating significant exposure within the body. These findings demonstrate that the developed method enables rapid and accurate detection and quantification of the five components in FZHY, offering a valuable reference for its clinical study.

383. Pharmacokinetics and Safety in Healthy Adults of RSM01, a Novel RSV Monoclonal Antibody, and Population PK Modeling to Support Pediatric Development

Abstract Background RSV is a common cause of infant respiratory infection and hospitalization. RSM01 is a novel anti-RSV mAb targeting the F glycoprotein essential for viral entry with a YTE mutation for half-life extension. Phase 1a PK and safety results are presented, along with an adult population PK model used to predict pediatric exposures via simulation. Methods In this double-blind Phase 1a study, healthy males and non-childbearing females aged 18-49 yrs were randomized 6:1 within dose cohorts to receive a single dose of RSM01 or placebo (PBO) in the following RSM01 dose sequence: 300mg IV, 300mg IM or 1000mg IV, 3000mg IV and cohort at 600mg IM. Serial serum samples were taken to measure RSM01 PK using a validated immunoassay method. A noncompartmental analysis (NCA) was conducted, and a population PK model was developed to characterize adult PK and predict pediatric PK using allometric scaling. Pediatric RSM01 PK was predicted for African infants at different IM doses. Results Overall, 56 participants received RSM01 (n=48) or PBO (n=8): median age 30 yrs (range 19-48), 52% male (n = 29), 66% White (n=37), median BMI 24.6 kg/m2 (range 18.1-29.4). 12/48 (25%) RSM01 recipients and 2/8 (25%) PBO recipients reported an AE, with no hypersensitivity reactions, serious AEs, or deaths reported. The median Tmax was ∼6–7 days after IM injection. Cmax and AUClast increased dose proportionally following IV administration. RSM01 adult PK was characterized using a two-compartment model with first-order elimination. IM absorption was described using a zero-order rate constant. Inter-individual variability was included for clearance (CL), central and peripheral volumes (V2 and V3). The RSM01 model estimated that distribution and a terminal half-life were 1.3 and 79.1 days, respectively, and IM bioavailability was ∼82%. The model predicted that following a 50 mg IM dose, median serum RSM01 concentration on day 150 in African infants 0-12 months old to be ∼ 28 mcg/mL, higher than the target exposure based on preclinical models (6.8 mcg/mL). Serum RSM01 NCA PK summary Note: AUClast and Cmax values are presented as geometric mean (CV). Tmax and Tlast are presented as median (min-max). Arithmetic Mean (±SD) Serum RSM01 Concentration-Time Curve by Treatment Note: Horizontal blue dashed line represents the target exposure based on preclinical models (6.8 mcg/mL). Conclusion RSM01 was shown to be well tolerated in healthy adults. Its long half-life and the predicted infant PK profiles support further pediatric development and indicate the potential for dosing once every RSV season. Disclosures Micha Levi, PhD, Bill &amp; Melinda Gates Medical Research Institute: Salary as a full-time employee Shayne Watson, MSc, Bill &amp; Melinda Gates Medical Research Institute: Salary as a full-time employee Dale Taylor, MD, Sanara Medtech Inc: Stocks/Bonds Luisa M. Stamm, MD, PhD, Bill &amp; Melinda Gates Medical Research Institute: Salary as a full-time employee Michael W. Dunne, MD, Bill &amp; Melinda Gates Medical Research Institute: Salary as a full-time employee

Russian development for drug independence in endocrinology: comparative analysis of bioequivalence, safety and tolerability of the first domestic liraglutide

Liraglutide is one of the analogues of the incretin hormone human glucagon-like peptide-1 (GLP-1) and is currently a priority treatment for diseases such as type 2 diabetes mellitus (mono- and combination therapy), obesity and overweight in the presence of at least one concomitant disease.The aim of the work was to assess the bioequivalence and comparability of the safety and tolerability profile of the drug Enligria® (liraglutide 6 mg/ml, Promomed RUS LLC, Russia) and the drug Saxenda® (liraglutide 6 mg/ml, Novo Nordisk AS, Denmark) after a single dose in healthy volunteers.Materials and methods. This study was an open-label, randomized, crossover comparative study to evaluate pharmacokinetic parameters, safety, tolerability and immunogenicity. The study comprised 26 healthy volunteers, 26 of whom were included in the bioequivalence assessment population. The study consisted of 2 periods, in each of which the volunteers received either the test drug (liraglutide at a single dose of 0.6 mg) or the reference drug (liraglutide at a single dose of 0.6 mg) once. The washout period between each dose was 7 days. Blood plasma samples were taken to determine the concentration of liraglutide in the range from 0 to 72 hours in each study period. Liraglutide concentrations were determined using a previously validated enzyme-linked immunosorbent assay (ELISA) method. A quantitative determination of antibodies to liraglutide in the blood serum samples was carried out using a microplate photometer and ready-made ELISA kits pre-validated by the manufacturer. The conclusion about the equivalence of the compared drugs was made based on the ratio of the parameters Cmax, AUC0→t and AUC0→t of the studied drug in relation to the reference one.Results. The pharmacokinetic parameters of the drugs were comparable to each other. The resulting 90% confidence intervals for the ratio of the values of Cmax, AUC0-t and AUC0-∞ of the Russian test and reference drug were 87.18–110.46, 84.40–104.11 and 86.69–103.22% respectively, which satisfied the criteria for assessing bioequivalence. The tolerability of the drugs in the volunteers was notified as good. The incidence of adverse events was comparable for the test and reference drugs. No serious adverse events were reported throughout the study. According to the results of the immunogenicity analysis, no antibodies to russian produced liraglutide were detected in the blood serum of the volunteers, which indicated the lack of the drug immunogenicity.Conclusion. During the study, the pharmacokinetic equivalence of the test and reference drugs was confirmed. The Russian drug Enligria® (liraglutide 6 mg/ml, Promomed RUS LLC, Russia) in comparison with a foreign drug Saxenda® (liraglutide 6 mg/ml, Novo Nordisk AS, Denmark).