Area Under The Concentration-time Curve Research Articles

Evaluation of target area under the concentration-time curve of vancomycin in an initial dosing design: a retrospective cohort study.

Area under the concentration-time curve (AUC)-guided dosing of vancomycin was introduced in a clinical setting; however, the target range of non-steady-state AUCs, such as Day 1 AUC and Day 2 AUC, remains controversial. Therefore, we sought to determine pharmacokinetic parameter thresholds and identify independent risk factors associated with acute kidney injury (AKI) to establish a safe initial dosing design for vancomycin administration. A single-centre, retrospective, cohort study of hospitalized patients treated with vancomycin was conducted to determine the threshold of both non-steady-state AUCs (Day 1 and 2 AUCs) and trough levels at the first blood sampling point (therapeutic drug monitoring, TDM). In addition, independent risk factors associated with AKI were evaluated using univariate and multivariate logistic regression analyses. The thresholds for predicting AKI were estimated as 456.6 mg·h/L for AUC0-24h, 554.8 mg·h/L for AUC24-48h, 1080.8 mg·h/L for AUC0-48h and 14.0 μg/mL for measured trough levels, respectively. In a multivariate analysis, Day 2 AUC ≥ 554.8 mg·h/L [adjusted odds ratio (OR), 57.16; 95% confidence interval (CI), 11.95-504.05], piperacillin/tazobactam (adjusted OR, 15.84; 95% CI, 2.73-127.70) and diuretics (adjusted OR, 4.72; 95% CI, 1.13-21.01) were identified as risk factors for AKI. We identified thresholds for both AUCs in the non-steady-state and trough levels at the first TDM. Our results highlight the importance of monitoring not only the AUC but also trough levels during vancomycin treatment to reduce the likelihood of AKI.

Relationship between nephrotoxicity and area under the concentration-time curve of vancomycin in critically ill patients: a multicenter retrospective study.

Vancomycin (VAN) is a glycopeptide antibiotic and one of the most commonly used antibiotics for severe infections caused by methicillin-resistant Staphylococcus aureus. However, higher VAN concentrations have been associated with an increased risk of acute kidney injury (AKI). Herein, we aimed to assess the frequency of AKI in different areas under the concentration-time curve (AUC) values of VAN using a two-point blood collection method, allowing for accurate AUC assessment in critically ill patients. We identified an association between AUC on day 2 and the risk of AKI in intensive care unit patients, suggesting that not only AUCs above 600 µg·h/mL but also those between 500 and 600 µg·h/mL pose a risk for AKI. Therefore, individualized dosing is feasible, with pharmacists being able to optimize VAN doses to attain appropriate targets.

Efficacy and Safety Factors Related to Plasma Concentration-Optimized Polymyxin B Therapy in Treating Carbapenem-Resistant Gram-Negative Bacterial Infections in China.

Polymyxin B (PMB)-based combination therapies are used to treat severe carbapenem-resistant gram-negative bacterial (CR-GNB) infections. This observational study investigated the relationship between clinical factors, including PMB concentration, and clinical efficacy and safety. Polymyxin B regimens were optimized through therapeutic drug monitoring (TDM) and area under the concentration-time curve (AUC). In all, 382 samples were tested from 130 patients. Logistic regression was used to analyze the relationships between variables with clinical efficacy and 30-day mortality factors were analyzed by Cox regression. The sensitivity and specificity of Cmin and AUC for the occurrence of acute kidney injury (AKI) were determined by ROC curve analysis. The clinical effectiveness of PMB was 65.4%. Multivariate logistic regression analysis revealed that lung infection, continuous renal replacement therapy, and C-reactive protein were independent factors significantly associated with efficacy. AKI occurred in 14.6% of the patients during treatment; age > 73 years (OR: 3.63; 95% CI: 1.035-12.727; P = 0.044), Cmin greater than 2.3 µg/mL (OR: 7.37; 95% CI: 1.571-34.580; P = 0.011), combined vancomycin (OR: 9.47; 95% CI: 1.732-51.731; P = 0.009), and combined piperacillin-tazobactam (OR: 21.87; 95% CI: 3.139-152.324; P = 0.002) were independent risk factors. The identified PMB cut-offs for predicting AKI were Cmin = 2.3 µg/mL and AUC = 82.0 mg h/L. Polymyxin B-based combination regimens are effective in treating CR-GNB infections, particularly bloodstream infections, but have shown unsatisfactory for lung infections. Cmin ≥ 2.3 µg /mL and AUC ≥ 82.0 mg h/L may increase PMB-associated AKI incidence. PMB dose should be adjusted based on TDM to ensure efficacy.

Inter-Species Pharmacokinetic Modeling and Scaling for Drug Repurposing of Pyronaridine and Artesunate.

Even though several new targets (mostly viral infection) for drug repurposing of pyronaridine and artesunate have recently emerged in vitro and in vivo, inter-species pharmacokinetic (PK) data that can extend nonclinical efficacy to humans has not been reported over 30 years of usage. Since extrapolation of animal PK data to those of humans is essential to predict clinical outcomes for drug repurposing, this study aimed to investigate inter-species PK differences in three animal species (hamster, rat, and dog) and to support clinical translation of a fixed-dose combination of pyronaridine and artesunate. PK parameters (e.g., steady-state volume of distribution (Vss), clearance (CL), area under the concentration-time curve (AUC), mean residence time (MRT), etc.) of pyronaridine, artesunate, and dihydroartemisinin (an active metabolite of artesunate) were determined by non-compartmental analysis. In addition, one- or two-compartment PK modeling was performed to support inter-species scaling. The PK models appropriately described the blood concentrations of pyronaridine, artesunate, and dihydroartemisinin in all animal species, and the estimated PK parameters in three species were integrated for inter-species allometric scaling to predict human PKs. The simple allometric equation (Y = a × Wb) well explained the relationship between PK parameters and the actual body weight of animal species. The results from the study could be used as a basis for drug repurposing and support determining the effective dosage regimen for new indications based on in vitro/in vivo efficacy data and predicted human PKs in initial clinical trials.

Model-Informed Development of a Cost-Saving Dosing Regimen for Sacituzumab Govitecan.

The antibody-drug conjugate sacituzumab govitecan is approved for metastatic triple-negative breast cancer and has shown promising results in various other types of cancer. Its costs may limit patient access to this novel effective treatment modality. The purpose of this study was to develop an evidence-based rational dosing regimen that results in targeted drug exposure within the therapeutic range while minimizing financial toxicity, to improve treatment access. Exposure equivalent dosing strategies were developed based on pharmacokinetic modeling and simulation by using the published pharmacokinetic model developed by the license holder. The alternative dose was based on the principle of using complete vials to prevent spillage and on the established non-linear relationship between body weight and systemic exposure. Equivalent exposure compared to the approved dosing regimen of 10 mg/kg was aimed for. Equivalent exposure was conservatively defined as calculated geometric mean ratios within the 0.9-1.11 boundaries for area under the concentration-time curve (AUC), trough concentration (Ctrough) and maximum concentration (Cmax) of the alternative dosing regimen compared to the approved dosing regimen. Since different vial sizes are available for the European Union (EU) and United States (US) market, because body weight distributions differ between these populations, we performed our analysis for both scenarios. Dosing regimens of sacituzumab govitecan for the EU (<50 kg: 400 mg, 50-80 kg: 600 mg, and >80 kg: 800 mg) and US population (<40 kg: 360 mg, 40-65 kg: 540 mg, 65-90 kg: 720 mg, and >90 kg: 900 mg) were developed, based on weight bands. The geometric mean ratios for all pharmacokinetic outcomes were within the predefined equivalence boundaries, while the quantity of drug used was 21.5% and 19.0% lower for the EU and US scenarios, respectively. With the alternative dosing proposal, an approximately 20% reduction in drug expenses for sacituzumab govitecan can be realized while maintaining an equivalent and more evenly distributed exposure throughout the body weight range, without notable increases in pharmacokinetic variability.

Model-Based Bioequivalence Analysis to Assess and Predict the Relative Bioavailability of Valproic Acid Formulations.

Model-based bioequivalence (MBBE) encompasses the use of nonlinear mixed effect models supporting the estimation of pharmacokinetic endpoints to assess the relative bioavailability between multi-source drug products. This application emerges as a valuable alternative to the standard non-compartmental analysis (NCA) in bioequivalence (BE) studies in which dense sampling is not possible. In this work, we aimed to assess the application of MBBE compared to traditional methods in evaluating the relative bioavailability of two formulations with different drug release properties. Additionally, we sought to predict the performance of a modified-release formulation in a multiple-dose scenario, leveraging data from a single-dose study. MBBE analysis was implemented to estimate the BE endpoints (90%CI for the Test/Reference geometric mean ratio, T/R GMR) in area under the concentration-time curve (AUC) and maximum concentration (Cmax) using data from a single-dose, 2-period, 2-sequence BE study performed in 14 healthy subjects between a locally developed valproic acid extended-release formulation (Test) and the brand-name delayed-release formulation (Reference). Results were compared with the standard approach, revealing that MBBE analysis achieved higher discrimination between formulations for Cmax, addressing limitations of the experimental sampling design and highlighting an advantage for this model-based analysis even when rich data are available. Additionally, the bioequivalence outcome under the multiple-dose scenario was predicted through a simulation-based study for both total and unbound valproic acid concentrations, considering the impact of valproic acid saturable binding on BE conclusions. The MBBE analysis was superior to the NCA approach in detecting product-related differences, overcoming limitations in the study experimental design. Predictions for the multiple-dose scenario preclude that the extended-release properties of the Test formulation would persist at steady state, resulting in lower peak-to-trough fluctuation and bioequivalent performance in terms of the extent of drug absorption. Overall, these results should discourage unnecessary experimentation in healthy subjects.

Study of the bioequivalence of drugs for veterinary use «Avecardit» and «Vetmedin S» in the body of dogs

This article reflects the results of a pharmacokinetic comparison of the reproducible drug based on pimobendan «Avecardit» with the reference drug «Vetmedin S» when used in dogs. The experiment used a sequential study design. A group of experimental dogs was formed, consisting of 7 animals (6 main and 1 reserve animal). Blood sampling was carried out before administration and after 10, 20, 40 min; 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 8, 10, 12 and 24 hours after drug administration. Key parameters assessed during the study: maximum concentration (Cmax) and time to reach it, area under the concentration-time curve (AUC) of the active substance of the drug in the blood serum of dogs. The article describes the main stages of the experiment, reagents and standard samples, the process of sample preparation of blood serum samples and HPLC-MS/MS analysis, and presents the results of a study of the bioequivalence of the drugs «Avecardit» and «Vetmedin S».The time to reach the maximum concentration of pimobendan (Tmax) in the blood serum averaged 0.67–1 hour for the drug «Avecardit», 1–1.5 hours for the drug «Vetmedin S».Maximum blood serum concentrations (Cmax) of pimobendan were in the range of 53,995–62,873 ng/ml for the study drug and 49,956–61,108 ng/ml for the reference drug. The 90% confidence intervals for the CmaxT/CmaxR and AUC0-tT/AUC0-tR ratios of pimobendan were within the range of 80–125%. The obtained results of the research work, from a scientific point of view, are a sufficient basis for recognizing the pharmacokinetic equivalence of the reproduced drug to the reference one.

Pharmacokinetics and Bioequivalence of Vardenafil Hydrochloride in Healthy Chinese Volunteers.

Vardenafil hydrochloride tablet is an inhibitor of phosphodiesterase type 5, primarily for the treatment of erectile dysfunction. This postprandial study evaluated the pharmacokinetics and bioequivalence of the test and reference formulations of vardenafil hydrochloride tablets in healthy Chinese volunteers. An open, randomized, single-center, single-dose, 2-period, 2-sequence bioequivalence test was conducted on 66 healthy subjects under fed conditions. Subjects were randomly assigned to a 20-mg test or reference formulation with a 7-day washout period. Venous blood samples (4mL) were collected from each subject 25 times spanning predose (0hour) to 24hours after dosing. The plasma concentration of vardenafil was determined by high-performance liquid chromatography-tandem mass spectrometry. Sixty-two volunteers completed the study. Under fed conditions, the maximum plasma concentration was 29.1ng/mL, the area under the concentration-time curve (AUC) from time 0 to the time of the last measurable concentration was 85.3ng•h/mL, and AUC from time 0 to infinity was 87.1ng•h/mL. The 90% confidence intervals of the geometric mean ratio of AUC time 0 to the time of the last measurable concentration and AUC from time 0 to infinity were within the bioequivalence acceptance range of 0.80-1.25. The test formulation was a bioequivalent alternative to the reference formulation when taken under fed conditions in healthy Chinese subjects.

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

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

Population pharmacokinetics of trastuzumab deruxtecan (T-DXd) in subjects with HER2-mutant and HER2-overexpressing non-small cell lung cancer (NSCLC).

e20537 Background: T-DXd is a novel human epidermal growth factor receptor 2 (HER2) targeting antibody drug conjugate, approved globally at the dose of 5.4 mg/kg in HER2-positive or HER2-low breast cancer (BC) and HER2-mutant (HER2m) NSCLC1,2. The aim of the analysis was to characterize the populaton pharmacokinetics (PopPK) of T-DXd and its released payload, deruxtecan (DXd), in HER2m or HER2-overexpressing (HER2-OE) NSCLC subjects using data across tumor types (BC, NSCLC and others) from 12 Phase 1 to 3 studies with T-DXd doses ranging from 0.8-8.0 mg/kg. Methods: Analysis wasperformed using nonlinear mixed-effects modeling methods in NONMEM (version 7.4.3), similar to the previous analysis in HER2-positive BC1. Covariate effects were explored on the PK parameters of T-DXd and DXd. Results: Analysis included data across 1822 subjects, including 346, 1128, and 348 subjects with NSCLC, BC, and other cancers, respectively. The PK of T-DXd and DXd were adequately described by a PopPK model, judging by standard model diagnostics3. Covariate effects on T-DXd and DXd steady-state area under the concentration-time curve (AUC) were not clinically meaningful (within 0.8 to 1.25 AUC ratio interval for tested covariate level versus reference), except for subjects with high body weight (e.g., 90 kg; 95th percentile) showing a 31% and 37% higher T-DXd and DXd AUC, respectively, relative to typical subject with 58 kg body weight (median).The T-DXd and DXd AUC were also similar across subjects with BC, HER2m or HER2-OE NSCLC, with the same T-DXd dose. T-DXd and DXd AUC in NSCLC subjects were similar across subjects with mild hepatic or mild or moderate renal impairment (vs. normal counterparts), region (Asia, North America, Europe, and rest of the world), and race-country (Asian-Japan, Asian-Non-Japan, and Non-Asian) groups. Conclusions: T-DXd and DXd exposures were similar across subjects with BC and HER2m or HER2-OE NSCLC, as well as across hepatic function, renal function, region, and race-country groups within NSCLC supporting the use of 5.4 mg/kg dose (approved dose in BC) in HER2m or HER2-OE NSCLC from PK perspective. Reference: Enhertu [package insert]. Basking Ridge, NJ: Daiichi Sankyo, Inc.; 2022. Enhertu [summary of product characteristics]. Daiichi Sankyo Europe GmbH, Munich; 2022 Yin O et al. Clin Pharmacol Ther. 2021;109(5):1314-1325. Clinical trial information: NCT04644237 , NCT03505710 .

P2X3 Receptor Antagonist Eliapixant in Phase I Clinical Trials: Safety and Inter-ethnic Comparison of Pharmacokinetics in Healthy Chinese and Japanese Participants.

Afferent neuronal hypersensitization via P2X3 receptor signaling has been implicated as a driver of several disorders, including refractory chronic cough, endometriosis, diabetic neuropathic pain, and overactive bladder. Eliapixant, a selective P2X3 receptor antagonist, has been in clinical development for all four disorders. This paper describes pharmacokinetic (PK) and safety data from two phase I studies of eliapixant in healthy Japanese and Chinese participants and compares those data within the two populations and with previous multiple dose data from Caucasian participants. Two separate phase I, single-center, randomized, placebo-controlled studies were conducted with healthy male participants. The Japanese study was single-blind and the Chinese study was double-blind. Eliapixant was administered as an oral amorphous solid dispersion immediate-release tablet in strengths of 25 mg, 75 mg, and 150 mg. PK characteristics after a single dose (SD) and at steady state (multiple dose [MD], twice daily), adverse events (AEs), and tolerability were evaluated. A post hoc comparison of PK characteristics after SD of eliapixant in Japanese and Chinese participants, and after MD of eliapixant in Japanese, Chinese, and Caucasian participants, was performed. Overall, 36/39 participants enrolled in the Japanese/Chinese studies, respectively (mean [standard deviation] age 25.4 [6.5] and 26.7 [5.0] years, respectively). After SD administration, maximum plasma concentration (Cmax) was higher among Japanese than Chinese participants in the 25 mg and 75 mg dose groups, but comparable in the 150 mg dose group. The area under the concentration-time curve (AUC) was comparable between Japanese and Chinese participants in the 25 mg and 75 mg dose groups, but lower among Japanese participants in the 150 mg group. Half-lives after SD and MD administration were also comparable in Japanese and Chinese participants. The post hoc analysis included 26 Japanese, 30 Chinese, and 50 Caucasian participants. Comparable exposure (Cmax,md and AUC[0-12]md) was observed after MD administration of eliapixant in Chinese and/or Japanese compared with Caucasian participants (geometric mean inter-ethnic ratios close to 1). The trough plasma concentration after eliapixant 150 mg MD, which was assumed to be relevant to eliapixant efficacy, was comparable across all ethnicity groups. Most AEs reported in the Japanese (eliapixant 75 mg SD, n = 2; eliapixant 150 mg MD, n = 2) and Chinese participants (eliapixant 25 mg SD, n = 7; eliapixant 75 mg SD, n = 6; eliapixant 150 mg SD, n = 7; eliapixant 150 mg MD, n = 9; placebo SD, n = 5; placebo MD, n = 1) were of mild intensity. Higher incidences of AEs in the Chinese population were likely due to differing standards of AE reporting between investigators. Eliapixant was well tolerated by Japanese and Chinese participants. The inter-ethnic evaluation demonstrated similar PK characteristics across Japanese, Chinese, and Caucasian participants. ClinicalTrials.gov identifier numbers: NCT04265781 and NCT04802343.

Validation and development of population pharmacokinetic model of vancomycin using a real-world database from a nationwide free web application

IntroductionVancomycin requires a population pharmacokinetic (popPK) model to estimate the area under the concentration-time curve (AUC), and an AUC-guided dosing strategy is necessary. This study aimed to develop a popPK model for vancomycin using a real-world database pooled from a nationwide web application (PAT). MethodsIn this retrospective study, the PAT database between December 14, 2022 and April 6, 2023 was used to develop a popPK model. The model was validated and compared with six existing models based on the predictive performance of datasets from another PAT database and the Kumamoto University Hospital. The developed model determined the dosing strategy for achieving the target AUC. ResultsThe modeling populations consisted of 7146 (13,372 concentrations from the PAT database), 3805 (7540 concentrations from the PAT database), and 783 (1775 concentrations from Kumamoto University Hospital) individuals. A two-compartment popPK model was developed that incorporated creatinine clearance as a covariate for clearance and body weight for central and peripheral volumes of distribution. The validation demonstrated that the popPK model exhibited the smallest mean absolute prediction error of 5.07, outperforming others (ranging from 5.10 to 5.83). The dosing strategies suggested a first dose of 30 mg/kg and maintenance doses adjusted for kidney function and age. ConclusionsThis study demonstrated the updating of PAT through the validation and development of a popPK model using a vast amount of data collected from anonymous PAT users.

Elucidating nonlinear pharmacokinetics of telmisartan: Integration of target-mediated drug disposition and OATP1B3-mediated hepatic uptake in a physiologically based model.

Telmisartan, a selective inhibitor of angiotensin II receptor type 1 (AT1), demonstrates nonlinear pharmacokinetics (PK) when orally administered in ascending doses to healthy volunteers, but the underlying mechanisms remain unclear. This study presents a physiologically based pharmacokinetic model integrated with target-mediated drug disposition (TMDD-PBPK model) to explore the mechanism of its nonlinear PK. We employed the Cluster-Gauss Newton method for top-down analysis, estimating the invivo Km,OATP1B3 (Michaelis-Menten constant for telmisartan hepatic uptake via Organic Anion Transporting Polypeptide 1B3) to be 2.0-5.7 nM. This range is significantly lower than the reported invitro value of 810 nM, obtained in 0.3% human serum albumin (HSA) conditions. Further validation was achieved through invitro assessment in plated human hepatocytes with 4.5% HSA, showing a Km of 4.5 nM. These results underscore the importance of albumin-mediated uptake effect for the hepatic uptake of telmisartan. Our TMDD-PBPK model, developed through a "middle-out" approach, underwent sensitivity analysis to identify key factors in the nonlinear PK of telmisartan. We found that the nonlinearity in the area under the concentration-time curve (AUC) and/or maximum concentration (Cmax) of telmisartan is sensitive to Km,OATP1B3 across all dosages. Additionally, the dissociation constant (Kd) for telmisartan binding to the AT1 receptor, along with its receptor abundance, notably influences PK at lower doses (below 20 mg). In conclusion, the nonlinear PK of telmisartan appears primarily driven by hepatic uptake saturation across all dose ranges and by AT1-receptor binding saturation, notably at lower doses.

Optimal exposure of mycophenolic acid for induction therapy of childhood lupus nephritis patients: an observational cohort study.

Mycophenolic acid (MPA) is recommended for lupus nephritis (LN) treatment, but with large inter-individual variability in pharmacokinetics (PK). The aim of this study is to reveal the relationship between MPA exposure and disease response and adverse drug reactions in pediatric LN patients. This was a population-based observational cohort study. A total of 86 pediatric LN patients treated with mycophenolate mofetil (MMF) for induction therapy were enrolled. The area-under the concentration-time curve (AUC) was calculated using MPA concentrations according to a limited sampling strategy. Receiver operating characteristic analysis was performed to assess the MPA-AUC threshold values. The cumulative incidence of renal remission and inactive systemic lupus erythematosus (SLE) over time was evaluated by Kaplan-Meier's analysis. MPA-AUC was identified as an independent factor associated with renal remission and lupus activity at 6 and 12 months after MMF treatment, and the improved renal remission rates were correlated with higher MPA-AUC, with thresholds of 29.81 and 30.63 μg·h·mL-1 at 6months and 12 months, respectively. Furthermore, the thresholds for maintaining the hypoactive state of LN were 30.96 and 31.19 μg·h·mL-1at 6 months and 12 months, respectively. Patients reaching target thresholds for MPA-AUC achieved renal response or stable disease earlier. In addition, the MPA-AUC threshold for decreasing MMF-related adverse reactions was 50.80 μg·h·mL-1. The initial and long-term treatments of pediatric LN patients with MMF should be individualized according to the MPA-AUC, and the recommended MPA exposure is 31.19-50.80 μg·h·mL-1.

Ex vivo pharmacokinetic/pharmacodynamic of hexahydrocolupulone against Clostridium perfringens in broiler chickens.

The economic impact of necrotizing enteritis (NE) resulting from Clostridium perfringens infection has been significant within the broiler industry. This study primarily investigated the antibacterial efficacy of hexahydrocolupulone against C. perfringens, and its pharmacokinetics within the ileal contents of broiler chickens. Additionally, a dosing regimen was developed based on the pharmacokinetic/pharmacodynamic (PK/PD) model specific to broiler chickens. Results of the study indicated that the minimum inhibitory concentration (MIC) of hexahydrocolupulone against C. perfringens ranged from 2 mg/L to 16 mg/L in MH broth. However, in ileal content, the MIC ranged from 8 mg/L to 64 mg/L. The mutation prevention concentration (MPC) in the culture medium was found to be 128 mg/L. After oral administration of hexahydrocolupulone at a single dosage of 10-40 mg/kg bodyweight, the peak concentration (Cmax), maximum concentration time (Tmax), and area under the concentration-time curve (AUC) in ileal content of broiler chickens were 291.42-3519.50 μg/g, 1-1.5 h, and 478.99-3121.41 μg h/g, respectively. By integrating the in vivo PK and ex vivo PD data, the AUC0-24h/MIC values required for achieving bacteriostatic, bactericidal, and bacterial eradication effects were determined to be 36.79, 52.67, and 62.71 h, respectively. A dosage regimen of 32.9 mg/kg at 24 h intervals for a duration of 3 days would yield therapeutic efficacy in broiler chickens against C. perfringens, provided that the MIC below 4 mg/L.

Abstract PO3-04-01: Population Pharmacokinetics of trastuzumab deruxtecan (T-DXd) in HER2-positive breast cancer subjects: analyses across 12 Phase 1-3 studies

Abstract Background: T-DXd, an antibody-drug conjugate composed of a humanized anti-HER2 monoclonal antibody and a topoisomerase I inhibitor payload, is approved for adult patients with unresectable or metastatic HER2-positive (HER2+) BC administered T-DXd 5.4 mg/kg Q3W with a prior anti-HER2–based therapy either in the metastatic setting, or in the neoadjuvant or adjuvant setting and have developed disease recurrence during or within six months of completing therapy. The objective of this analysis was to present pharmacokinetic (PK) characterization of T-DXd and DXd in patients with advanced/metastatic HER2-positive breast cancer from a pooled data source of 12 phase 1 to 3 clinical trials. Methods: Data from subjects with HER2-positive breast cancer and other solid tumors enrolled in studies DS8201-A-J101, DS8201-A-J102, DS8201-A-A103, DS8201-A-A104, DS8201-A-U201, DS8201-AJ202, DS8201-A-U205, DS8201-A-U204, DS8201-A-U206, DS8201-A-U301, DS8201-A-U302, and DS8201-A-U303 were used for this analysis. A population PK (PopPK) analysis was performed using nonlinear mixed effects modeling approach using NONMEM® (version 7.4.3). The effect of significant covariates was evaluated by univariate and multivariate analyses on steady-state exposure of T-DXd and DXd. Results: Data across T-DXd doses 0.8 to 8 mg/kg with 2216 subjects were included. The PK of T-DXd and DXd were adequately described by PopPK analysis based on standard model diagnostic techniques. T-DXd elimination clearance and volume of distribution of central and peripheral compartments were estimated at 0.402 L/day, 2.68 L and 5.91 L, respectively. DXd elimination clearance was estimated at 18.4 L/hour. Covariates previously detected to be statistically significant (cancer type, tumor size, albumin, race-country, body weight and sex for T-DXd; age, cancer type, AST, total bilirubin, ritonavir or itraconazole use, race-country, formulation and body weight for DXd) were retained in the PopPK model. No new covariates were identified as statistically significant in the PopPK analysis. All covariates were contained within the 0.8 to 1.25 exposure ratio interval in T-DXd and DXd steady-state area under the concentration-time curve (AUC), indicating no clinically meaningful effect, except for subjects with high body weight (90 kg; 95th percentile) showing a 28% and 26% higher T-DXd and DXd AUC, respectively, relative to a BC subject with median body weight of 60 kg. None of these changes were clinically meaningful based on exposure-response analyses of efficacy and safety endpoints. T-DXd and DXd post hoc exposure estimates in all BC subjects (HER2-positive and HER2-low) as well as BC subjects with HER2- positive were comparable across hepatic function, renal function, region, race-country and line of therapy. Conclusions: Similar T-DXd and DXd exposures were obtained for the recommended dosing of 5.4 mg/kg Q3W T-DXd in BC subjects across categories of hepatic function, renal function, region, race-country, HER2 status, and line of therapy. Citation Format: Claire Li, Stefanie henning, Kashyap Patel, Katrina Hui, Gerly van der Vleuten, malaz Abutarif, Tushar Garimella, Amit Khatri. Population Pharmacokinetics of trastuzumab deruxtecan (T-DXd) in HER2-positive breast cancer subjects: analyses across 12 Phase 1-3 studies [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-04-01.

Population pharmacokinetics and exposure-response analyses of polatuzumab vedotin in patients with previously untreated DLBCL from the POLARIX study.

Polatuzumab vedotin is a CD79b-directed antibody-drug conjugate that targets B cells and delivers the cytotoxic payload monomethyl auristatin E (MMAE). The phase III POLARIX study (NCT03274492) evaluated polatuzumab vedotin in combination with rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHP) as first-line treatment of diffuse large B-cell lymphoma (DLBCL). To examine dosing decisions for this regimen, population pharmacokinetic (popPK) analysis, using a previously developed popPK model, and exposure-response (ER) analysis, were performed. The popPK analysis showed no clinically meaningful relationship between cycle 6 (C6) antibody-conjugated (acMMAE)/unconjugated MMAE area under the concentration-time curve (AUC) or maximum concentration, and weight, sex, ethnicity, region, mild or moderate renal impairment, mild hepatic impairment, or other patient and disease characteristics. In the ER analysis, C6 acMMAE AUC was significantly associated with longer progression-free and event-free survival (both p = 0.01). An increase of <50% in acMMAE/unconjugated MMAE exposure did not lead to a clinically meaningful increase in adverse events of special interest. ER data and the benefit-risk profile support the use of polatuzumab vedotin 1.8 mg/kg once every 3 weeks with R-CHP for six cycles in patients with previously untreated DLBCL.

Clinical assessment of momelotinib drug-drug interactions via CYP3A metabolism and transporters.

Momelotinib-approved for treatment of myelofibrosis in adults with anemia-and its major active metabolite, M21, were assessed as drug-drug interaction (DDI) victims with a strong cytochrome P450 (CYP) 3A4 inhibitor (multiple-dose ritonavir), an organic anion transporting polypeptide (OATP) 1B1/1B3 inhibitor (single-dose rifampin), and a strong CYP3A4 inducer (multiple-dose rifampin). Momelotinib DDI perpetrator potential (multiple-dose) was evaluated with CYP3A4 and breast cancer resistance protein (BCRP) substrates (midazolam and rosuvastatin, respectively). DDI was assessed from changes in maximum plasma concentration (Cmax), area under the concentration-time curve (AUC), time to reach Cmax, and half-life. The increase in momelotinib (23% Cmax, 14% AUC) or M21 (30% Cmax, 24% AUC) exposure with ritonavir coadministration was not clinically relevant. A moderate increase in momelotinib (40% Cmax, 57% AUC) and minimal change in M21 was observed with single-dose rifampin. A moderate decrease in momelotinib (29% Cmax, 46% AUC) and increase in M21 (31% Cmax, 15% AUC) were observed with multiple-dose rifampin compared with single-dose rifampin. Due to potentially counteracting effects of OATP1B1/1B3 inhibition and CYP3A4 induction, multiple-dose rifampin did not significantly change momelotinib pharmacokinetics compared with momelotinib alone (Cmax no change, 15% AUC decrease). Momelotinib did not alter the pharmacokinetics of midazolam (8% Cmax, 16% AUC decreases) or 1'-hydroxymidazolam (14% Cmax, 16% AUC decreases) but increased rosuvastatin Cmax by 220% and AUC by 170%. Safety findings were mild in this short-term study in healthy volunteers. This analysis suggests that momelotinib interactions with OATP1B1/1B3 inhibitors and BCRP substrates may warrant monitoring for adverse reactions or dose adjustments.

Evaluation of Bioequivalence for Avapritinib Tablets in Chinese Participants Under Fasting Conditions Using a Reference-Scaled Average Bioequivalence Method.

This study aimed to assess the bioequivalence of 2 avapritinib tablets formulations. A randomized, open-label, single-center trial was conducted on fasting, healthy Chinese participants. The study utilized a partial replicated design with 3 sequences and 3 periods. Participants were assigned to 1 of 3 sequences, with each sequence receiving the reference formulation twice and the test formulation once. Plasma samples were collected and analyzed to determine pharmacokinetic parameters. The bioequivalence of the 2 avapritinib formulations was assessed using reference-scaled average bioequivalence for the maximum plasma concentration (Cmax) and the average bioequivalence analysis for the area under the concentration-time curve (AUC). Out of 39 participants, 38 completed the study. For Cmax, the 1-sided 95% upper confidence interval (CI) bound from the scaled approach was -0.035 (<0) and the point estimate value was 0.958, falling inside the acceptance range of 0.8-1.25. For both the AUC over all concentrations measured (AUC0-t) and the AUC from time 0 to infinity (AUC0-inf), the 90% CIs of geometric mean ratios (0.87-1.01) also met the bioequivalence criteria of 0.8-1.25. Consequently, the study demonstrated that the 2 avapritinib formulations were bioequivalent under fasting conditions.

Clinical activity, pharmacokinetics, and pharmacodynamics of oral hypomethylating agents for myelodysplastic syndromes/neoplasms and acute myeloid leukemia: A multidisciplinary review.

To review the pharmacokinetic (PK)-pharmacodynamic (PD) profiles, disease setting, dosing, and safety of oral and parenteral hypomethylating agents (HMAs) for the treatment of myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML), and to provide a multidisciplinary perspective on treatment selection and educational needs relating to HMA use. Clinical and real-world data for parenteral decitabine and azacitidine and two oral HMAs: decitabine-cedazuridine (DEC-C) for MDS and azacitidine (CC-486) for AML maintenance therapy. Differences in the PK-PD profiles of oral and parenteral HMA formulations have implications for their potential toxicities and planned use. Oral DEC-C (decitabine 35 mg and cedazuridine 100 mg) has demonstrated equivalent systemic area under the concentration-time curve (AUC) exposure to a 5-day regimen of intravenous (IV) decitabine 20 mg/m2 and showed no significant difference in PD. The AUC equivalence of oral DEC-C and IV decitabine means that these regimens can be treated interchangeably (but must not be substituted within a cycle). Oral azacitidine has a distinct PK-PD profile versus IV or subcutaneous azacitidine, and the formulations are not bioequivalent or interchangeable owing to differences in plasma time-course kinetics and exposures. Clinical trials are ongoing to evaluate oral HMA combinations and novel oral HMAs, such as NTX-301 and ASTX030. Treatment with oral HMAs has the potential to improve quality of life, treatment adherence, and disease outcomes versus parenteral HMAs. Better education of multidisciplinary teams on the factors affecting HMA treatment selection may help to improve treatment outcomes in patients with MDS or AML.