Key Pharmacokinetic Parameters Research Articles

A high-precision view of intercompartmental drug transport via simultaneous, seconds-resolved, in situ measurements in the vein and brain.

The ability to measure specific molecules at multiple sites within the body simultaneously, and with a time resolution of seconds, could greatly advance our understanding of drug transport and elimination. As a proof-of-principle demonstration, here we describe the use of electrochemical aptamer-based (EAB) sensors to measure transport of the antibiotic vancomycin from the plasma (measured in the jugular vein) to the cerebrospinal fluid (measured in the lateral ventricle) of live rats with temporal resolution of a few seconds. In our first efforts, we made measurements solely in the ventricle. Doing so we find that, although the collection of hundreds of concentration values over a single drug lifetime enables high-precision estimates of the parameters describing intracranial transport, due to a mathematical equivalence, the data produce two divergent descriptions of the drug's plasma pharmacokinetics that fit the in-brain observations equally well. The simultaneous collection of intravenous measurements, however, resolves this ambiguity, enabling high-precision (typically of ±5 to ±20% at 95% confidence levels) estimates of the key pharmacokinetic parameters describing transport from the blood to the cerebrospinal fluid in individual animals. The availability of simultaneous, high-density 'in-vein' (plasma) and 'in-brain' (cerebrospinal fluid) measurements provides unique opportunities to explore the assumptions almost universally employed in earlier compartmental models of drug transport, allowing the quantitative assessment of, for example, the pharmacokinetic effects of physiological processes such as the bulk transport of the drug out of the CNS via the dural venous sinuses.

Encapsulation of Alpinia leaf essential oil in nanophytosome-embedded gel as novel strategy to treat periodontal infections: evaluation of antimicrobial effectiveness, pharmacokinetic, in vitro-ex vivo correlation and in silico studies

Aim The work reports a novel nanophytosomal gel encapsulating Alpinia galanga (L.) Willd leaf essential oil to treat periodontal infections. Methods Alpinia oil-loaded nanophytosomes (ANPs) were formulated by lipid layer hydration technique and were evaluated by FESEM, cryo-TEM, loading efficiency, zeta potential, particle size, release profile etc. Selected ANPs-loaded gel (ANPsG) was evaluated by both in vitro and in vivo methods. Results Selected ANPs were spherical, unilamellar, 49.32 ± 2.1 nm size, 0.45 PDI, −46.7 ± 0.8 mV zeta potential, 9.8 ± 0.5% (w/w) loading, 86.4 ± 3.02% (w/w) loading efficiency with sustained release profile. ANPsG showed good spreadability (6.8 ± 0.3 gm.cm/sec), extrudability (79.33 ± 1.5%), viscosity (36522 ± 0.82 cps), mucoadhesive strength (44.56 ± 3.5 gf) with sustained ex vivo release tendency. Satisfied ZOI and MIC was observed for ANPsG against periodontal bacteria vs. standard/control. ANPsG efficiently treated infection in ligature induced periodontitis model. Key pharmacokinetic parameters like AUC, MRT, Vd were enhanced for ANPsG. Conclusion ANPsG may be investigated for futuristic clinical studies.

Penciclovir pharmacokinetics after oral and rectal administration of famciclovir in African elephants (Loxodonta africana) shows that effective concentrations can be achieved from rectal administration, despite lower absorption.

To evaluate the pharmacokinetics of famciclovir and its metabolite penciclovir following a single dose administered orally and rectally in African elephants (Loxodonta africana). 15 African elephants (6 males and 9 females) of various ages. Famciclovir (15 mg/kg) was administered orally or per rectum once, with at least a three-week washout period between administrations. Blood was collected at 13 different timepoints per administration for 6 elephants, occurring between February and March 2020. An additional 9 elephants were sampled at variable timepoints per administration utilizing a sparse sampling design between July 2020 and January 2021. Plasma famciclovir and penciclovir levels were measured via HPLC and fluorescence detection. Pharmacokinetic analysis was completed in the summer of 2021 using noncompartmental analysis and nonlinear mixed-effects modeling. Famciclovir was not detected in any sample, suggesting complete metabolism. Key pharmacokinetic parameters for penciclovir following oral administration were time to maximum concentration (tmax; 2.12 hours), area under the concentration-versus-time curve (AUC; 33.93 μg·h/mL), maximum observed concentration (Cmax; 3.73 μg/mL), and absorption half-life (t1/2; 0.65 hours). Following rectal administration, the values were: tmax, 0.65 hours; AUC, 15.62 μg·h/mL; Cmax, 2.52 μg/mL; and absorption t1/2, 0.13 hours. Famciclovir was rapidly metabolized to penciclovir. Oral administration resulted in slower absorption but higher maximum plasma concentration and higher AUC compared to rectal administration. African elephants administered famciclovir via oral and rectal routes resulted in measurable serum penciclovir, and these findings may be utilized by clinicians treating viral infections in this species.

Evaluation of Ornidazole Tablets Bioequivalence in Chinese Healthy Participants Under Fasted and Fed Conditions Using Pharmacokinetic Parameters.

Ornidazole, the third generation of nitroimidazole derivatives after metronidazole and tinidazole, it exerts both bactericidal and antiprotozoal effects. The purpose of this study was to evaluate the pharmacokinetic and bioequivalence of two ornidazole tablets manufactured by two different manufacturers based on their pharmacokinetic parameters. Fasted and fed healthy Chinese volunteers participated in a randomized sequence, single-dose, open-label, two-period crossover trial. There were 24 participants in both the fed studyand the fastedstudy. Following a 7-day washout period before receiving the alternative formulation, eligible research participants were randomly assigned (1:1) to receive a single dosage of either the reference formulation or the test formulation. Following tablet administration, plasma samples were obtained over 72 h and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS) to evaluate ornidazole contents. maximum plasma concentration (Cmax), time to Cmax (Tmax),the area under the curve (AUC) from t = 0 to infinity (AUC0-∞), AUCfrom t = 0 to the last quantifiable concentration (AUC0-t), half-life (t1/2),and terminal elimination rate constant (z) were evaluated as pharmacokinetic (PK) parameters. The safety evaluation involved adverse events (AEs) incidence and alterations in laboratory tests (hepatic function, blood biochemistry, hematology, and urinalysis) or vital signs (temperature, pulse, and blood pressure). For the bioequivalence assessment in the fast trial, the prime PK parameters comparison between the reference and test formulation revealed that the GMR (90% CI) values for AUC0-t, Cmax, and AUC0-∞ were 100.97% (99.12-102.85%), 99.88% (90.63-110.08%), and 101.12% (99.17-103.11%), respectively. For the bioequivalence assessment in the fed trial, the key PK parameters comparison between the reference and test formulations revealed that the GMR (90% CI) values for AUC0-t, Cmax, and AUC0-∞ were 103.00% (100.94-105.11%), 101.90% (99.63-104.22%), and 102.99% (100.87-105.16%), respectively. The geometric mean ratios (GMRs) for the primary pharmacokinetic parameters (Cmax, AUC0-72, and AUC0-∞) between the two formulations and the corresponding 90% confidence intervals (CIs) were all within the range of 80.00-125.00% for both the fasting and fed states. Both treatments have comparable safety profiles. The bioequivalence and tolerability of ornidazole tablet reference and test formulations were evaluated among healthy Chinese participants under both fasting and fed conditions. The results indicated that both formulations were bioequivalent and generally well tolerated; besides, the interaction between food and drug may affect drug pharmacokinetics. CTR20212873, registered on 15 November 2021; ChiCTR2300069098, registered on 7 March 2023.

Deep-NCA: A deep learning methodology for performing noncompartmental analysis of pharmacokinetic data.

Noncompartmental analysis (NCA) is a model-independent approach for assessing pharmacokinetics (PKs). Although the existing NCA algorithms are very well-established and widely utilized, they suffer from low accuracies in the setting of sparse PK samples. In response, we developed Deep-NCA, a deep learning (DL) model to improve the prediction of key noncompartmental PK parameters. Our methodology utilizes synthetic PK data for model training and uses an innovative patient-specific normalization method for data preprocessing. Deep-NCA demonstrated adequate performance across six previously unseen simulated drugs under multiple dosing, showcasing effective generalization. Compared to traditional NCA, Deep-NCA exhibited superior performance for sparse PK data. This study advances the application of DL to PK studies and introduces an effective method for handling sparse PK data. With further validation and refinement, Deep-NCA could significantly enhance the efficiency of drug development by providing more accurate NCA estimates while requiring fewer PK samples.

Physiologically Based Pharmacokinetic (PBPK) Model Predictions of Disease Mediated Changes in Drug Disposition in Patients with Nonalcoholic Fatty Liver Disease (NAFLD).

This study was designed to verify a virtual population representing patients with nonalcoholic fatty liver disease (NAFLD) to support the implementation of a physiologically based pharmacokinetic (PBPK) modeling approach for prediction of disease-related changes in drug pharmacokinetics. A virtual NAFLD patient population was developed in GastroPlus (v.9.8.2) by accounting for pathophysiological changes associated with the disease and proteomics-informed alterations in the abundance of metabolizing enzymes and transporters pertinent to drug disposition. The NAFLD population model was verified using exemplar drugs where elimination is influenced predominantly by cytochrome P450 (CYP) enzymes (chlorzoxazone, caffeine, midazolam, pioglitazone) or by transporters (rosuvastatin, 11C-metformin, morphine and the glucuronide metabolite of morphine). PBPK model predictions of plasma concentrations of all the selected drugs and hepatic radioactivity levels of 11C-metformin were consistent with the clinically-observed data. Importantly, the PBPK simulations using the virtual NAFLD population model provided reliable estimates of the extent of changes in key pharmacokinetic parameters for the exemplar drugs, with mean predicted ratios (NAFLD patients divided by healthy individuals) within 0.80- to 1.25-fold of the clinically-reported values, except for midazolam (prediction-fold difference of 0.72). A virtual NAFLD population model within the PBPK framework was successfully developed with good predictive capability of estimating disease-related changes in drug pharmacokinetics. This supports the use of a PBPK modeling approach for prediction of the pharmacokinetics of new investigational or repurposed drugs in patients with NAFLD and may help inform dose adjustments for drugs commonly used to treat comorbidities in this patient population.

Systemic and Brain Pharmacokinetics of Milnacipran in Mice: Comparison of Intraperitoneal and Intravenous Administration.

Milnacipran is a dual serotonin and norepinephrine reuptake inhibitor, clinically used for the treatment of major depression or fibromyalgia. Currently, there are no studies reporting the pharmacokinetics (PK) of milnacipran after intraperitoneal (IP) injection, despite this being the primary administration route in numerous experimental studies using the drug. Therefore, the present study was designed to investigate the PK profile of IP-administered milnacipran in mice and compare it to the intravenous (IV) route. First a liquid chromatography-mass spectrometry (LC-MS/MS) method was developed and validated to accurately quantify milnacipran in biological samples. The method was used to quantify milnacipran in blood and brain samples collected at various time-points post-administration. Non-compartmental and PK analyses were employed to determine key PK parameters. The maximum concentration (Cmax) of the drug in plasma was at 5 min after IP administration, whereas in the brain, it was at 60 min for both routes of administration. Curiously, the majority of PK parameters were similar irrespective of the administration route, and the bioavailability was 92.5% after the IP injection. These findings provide insight into milnacipran's absorption, distribution, and elimination characteristics in mice after IP administration for the first time and should be valuable for future pharmacological studies.

Abstract C024: Trial in progress: Phase 1 study of BAL0891 as monotherapy and in combination with chemotherapy in patients with advanced solid tumors

Abstract Background: BAL0891 is a first-in-class small-molecule mitotic checkpoint inhibitor (MCI) that targets threonine tyrosine kinase (TTK) and polo-like kinase 1 (PLK1) to disrupt spindle assembly checkpoint (SAC) regulation and induce tumor cell death. It has a more potent anti-tumor activity as compared to TTK-specific inhibitors due to its combined prolonged effect on TTK and transient effect on PLK1. In preclinical studies, BAL0891 demonstrated potent anti-tumor activity as a monotherapy and in combination with paclitaxel and carboplatin. In the first-in-human microdose study of TTK-CS-001 in healthy subjects, key BAL0891 pharmacokinetic (PK) parameters were investigated (i.e., clearance, half-life, exposure), and no safety signals were detected. Trial design: This clinical trial is a multiple-cohort, open-label phase 1 study with 3 dose-escalation substudies, investigating intravenous (IV) BAL0891 as monotherapy, and in combination with carboplatin or paclitaxel, in patients with advanced solid tumors. Primary objectives: 1) To evaluate safety/tolerability 2) To estimate the maximum tolerated dose (MTD) and/or recommended Phase 2 dose (RP2D) of BAL0891 monotherapy and in combination with carboplatin/paclitaxel. Eligibility: Patients ages ≥18 years with advanced/metastatic solid tumors that are refractory to, or intolerant of existing therapy may participate in this study. Patients enrolled in dose level ≥4 of Substudy 1 and all patients in Substudies 2 and 3 must have measurable disease. Substudy 1: Monotherapy BAL0891: IV doses of BAL0891 on Days 1 (D1) and 8 (D8) every 3 weeks (Q3W). A Bayesian logistic regression model (BLRM) will guide dose escalations, with 8 nominal DLs of 5/10/20/40/80/160/320/480 mg. Substudy 2: Phase 1 BAL0891 D1, D8 + carboplatin AUC5-6 D1 Q3W. Substudy 3: Phase 1 BAL0891 D1, D15 + paclitaxel 70-80 mg/m2 D1, D8, D15 Q4W. Substudies 2 and 3 may begin once the maximum tolerated dose (MTD) of BAL0891 monotherapy has been established or at the first signs of expected target toxicity and/or efficacy with monotherapy. Enrollment began in February 2023 and is ongoing in the United States and South Korea. Clinical trial information; NCT05768932 Citation Format: Shivaani Kummar, Minal Barve, Eric Feldman, Seunghyun Ma, Jaime Merchan, Seock-Ah Im, Sun Young Rha. Trial in progress: Phase 1 study of BAL0891 as monotherapy and in combination with chemotherapy in patients with advanced solid tumors [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 C024.

Bioequivalence and Pharmacokinetics Study of Two Zidovudine/Lamivudine Tablets in Chinese Healthy Volunteers.

Zidovudine/lamivudine tablets are nucleoside reverse transcriptase inhibitors that are used to treat human immunodeficiency virus. The objective of this study was to investigate the bioequivalence and pharmacokinetics (PKs) of test and reference preparations of zidovudine/lamivudine tablets in healthy Chinese subjects. We designed a randomized, open, single-center, single-dose, 2-crossover experiment with a 7-day washout period involving 20 healthy subjects. The subjects were given a single dose of the test or reference preparation after fasting overnight for 10hours. Blood samples were subsequently collected at scheduled time points from 0hour (preadministration) up to 24hours postadministration. The plasma concentrations of zidovudine and lamivudine were determined by a validated ultra-performance liquid chromatography-tandem mass spectrometry method. Analysis of variance (ANOVA) was used to compare differences in the mean values of key PK parameters between the 2 preparations. Bioequivalence was evaluated by 2 one-sided t-tests and 90% confidence intervals (CIs) of the geometric mean ratio (GMR). In total, 19 of the 20 subjects completed the trial. Based on the analysis of PK parameters, the relative bioavailability of zidovudine and lamivudine was 101.1% ± 2.0% and 100.3% ± 1.5%, respectively. ANOVA found no significant difference in primary PK parameters when compared between the 2 formulations, and the 90% CIs of the GMR of the 2 formulations were within the bioequivalence margins of 80%-125%. No serious adverse events occurred. Thus, we confirmed that the 2 preparations were bioequivalent in healthy Chinese volunteers. Our analysis demonstrated that both products showed good tolerance in all subjects.

Shared learning from a physiologically based pharmacokinetic modeling strategy for human pharmacokinetics prediction through retrospective analysis of Genentech compounds.

The quantitative prediction of human pharmacokinetics (PK) including the PK profile and key PK parameters are critical for early drug development decisions, successful phase I clinical trials, and the establishment of a range of doses to enable phase II clinical dose selection. Here, we describe an approach employing physiologically based pharmacokinetic (PBPK) modeling (Simcyp) to predict human PK and to validate its performance through retrospective analysis of 18 Genentech compounds for which clinical data are available. In short, physicochemical parameters and in vitro data for preclinical species were integrated using PBPK modeling to predict the in vivo PK observed in mouse, rat, dog, and cynomolgus monkey. Through this process, the in vitro to in vivo extrapolation (IVIVE) was determined and then incorporated into PBPK modeling in order to predict human PK. Overall, the prediction obtained using this PBPK-IVIVE approach captured the observed human PK profiles of the compounds from the dataset well. The predicted Cmax was within 2-fold of the observed Cmax for 94% of the compounds while the predicted area under the curve (AUC) was within 2-fold of the observed AUC for 72% of the compounds. Additionally, important IVIVE trends were revealed through this investigation, including application of scaling factors determined from preclinical IVIVE to human PK prediction for each molecule. Based upon the analysis, this PBPK-based approach now serves as a practical strategy for human PK prediction at the candidate selection stage at Genentech.

Comparison of Intravenous Microdialysis and Standard Plasma Sampling for Monitoring of Vancomycin and Meropenem Plasma Concentrations-An Experimental Porcine Study.

Microdialysis is a catheter-based method suitable for dynamic sampling of unbound antibiotic concentrations. Intravenous antibiotic concentration sampling by microdialysis has several advantages and may be a superior alternative to standard plasma sampling. We aimed to compare concentrations obtained by continuous intravenous microdialysis sampling and by standard plasma sampling of both vancomycin and meropenem in a porcine model. Eight female pigs received 1 g of both vancomycin and meropenem, simultaneously over 100 and 10 min, respectively. Prior to drug infusion, an intravenous microdialysis catheter was placed in the subclavian vein. Microdialysates were collected for 8 h. From a central venous catheter, plasma samples were collected in the middle of every dialysate sampling interval. A higher area under the concentration/time curve and peak drug concentration were found in standard plasma samples compared to intravenous microdialysis samples, for both vancomycin and meropenem. Both vancomycin and meropenem concentrations obtained with intravenous microdialysis were generally lower than from standard plasma sampling. The differences in key pharmacokinetic parameters between the two sampling techniques underline the importance of further investigations to find the most suitable and reliable method for continuous intravenous antibiotic concentration sampling.

Conveyance of sofosbuvir through vesicular lipid nanocarriers as an effective strategy for management of viral meningitis.

This study aimed to deliver a potential water-soluble antiviral drug (sofosbuvir) through optimized vesicular lipid nanocarriers (LNs) to the rat brain as a novel strategy against viral meningitis. A 23 factorial design approach was established to assess the effect of formulation composition and process variables on the physicochemical properties of the LNs. Sofosbuvir-loaded LNs (SLNs) were developed by lipid layer hydration method utilizing optimized parameters and evaluated for various in vitro characterizations like FTIR, DSC, XRD, FESEM, vesicle size, zeta potential, drug carrying capacity and drug release. Plasma and brain pharmacokinetic (PK) studies were conducted in Sprague-Dawley rats. FTIR data depicted the absence of any major interaction between the drug and the excipients. DSC revealed a sharp endothermic peak for the drug. XRD showed the amorphic nature of the SLNs. Optimized SLNs were spherical as depicted from FESEM with 42.43 nm size, -49.21 mV zeta potential, 8.31% drug loading and sustained drug release in vitro. Plasma/brain PK studies depicted significant improvement in key PK parameters, viz. AUC, AUMC, MRT, and Vd, compared to those for the free drug. A more than 3.5-fold increase in MRT was observed for optimized SLNs (11.2 h) in brain tissue compared to the free drug (3.7 h). Ex vivo hemolysis data confirmed the non-toxic nature of the SLNs to human red blood cells. In silico docking study further confirmed strong interaction between the drug and selected protein 4YXP (herpes simplex) with docking score of -7.5 and 7EWQ protein (mumps virus) with docking score of -7.3. The optimized SLNs may be taken for further in vivo studies to pave the way towards clinical translation.

Comparative clinical study of pharmacokinetics and bioequivalence of Relonova and Maxalt

Evaluation of the bioequivalence of the tested Relonova, tablets, 10 mg and Maxalt, tablets, 10 mg drugs on an empty stomach in healthy volunteers. The pharmacokinetic analysis population included 40 volunteers, the safety analysis population included 40 volunteers. The average age of randomized volunteers (men - 20, women - 20) was 29.3±8.9 years, height 1.71±0.09 m, body weight 70.86±11.66 kg, mean BMI 24.18±2.81 kg/m2. The method used high performance liquid chromatography with tandem mass spectrometric detection. Statistical analysis of the obtained data was performed based on the assumption of a log-normal distribution of the parameters AUC0-72 and Cmax. The ratio of geometric means for the key pharmacokinetic parameters (AUC0-t, AUC0-inf and Cmax) of rizatriptan is close to 90%, CI is within the acceptable range for bioequivalent drugs (80-125%). The intrasubject variability (CVintra) for rizatriptan was 23.74% (Cmax), 10.94% (AUC0-t). The average profiles of the pharmacokinetic curves of rizatriptan when taking the test and reference drugs have similar shapes. Relonova and reference Maxalt are bioequivalent. The results of the study make it possible to recommend Relonova for further clinical study and wide practical application.

Pharmacokinetics of a novel anti-platelet drug from the glycoprotein IIb/IIIa receptor inhibitors group

Relevance. As part of the conducted open non-randomized phase I clinical trial the pharmacokinetics (PK) of the first Russian novel antiplatelet agent Angipur (nonpeptide glycoprotein IIb/IIIa receptor inhibitor) was studied.Aim of the research was to evaluate PK parameters of Angipur in healthy volunteers after single dose ascending infusions.Methods. 20 male healthy volunteers were enrolled in this phase I trial. Angipur (0.02% concentrate solution for infusion) was administered to every subject in single doses 0.015, 0.05, 0.09 mg/kg for 3 consecutive days. PK parameters were evaluated.Results. After single intravenous administration of doses 0.015, 0.05, 0.09 mg/kg to healthy volunteers the peak plasma concentration of Angipur was reached at the end of the infusion, and then the plasma concentration rapidly decreased 15 minutes after the end of the infusion followed by slow decrease for 12 hours. Dose proportionality for key PK parameters was established. After single infusions of doses 0.015, 0.05, 0.09 mg/kg mean AUC0-t was 27.11, 92.04 and 180.39 ng× h/ml; mean AUC0-¥ – 37.03, 125.76 and 239.61 ng×h/ml; mean Сmax – 12.44, 46.1 and 92.48 ng/ml; mean Vd – 304.01, 299.67 and 252.96 l; mean Т1/2 – 6.72, 6.84 and 6.06 h; Сl – 32.19, 32.29 and 31.55 l/h; kel – 0.1073, 0.1109 and 0.1257 l/h; MRT – 8.94, 8.93 and 8.18 h.Conclusion. Pharmacokinetics of Angipur in studied doses demonstrated linearity, rapid reaching of Сmax immediately after the infusion and the high distribution of the drug in tissues and biological fluids of the human organism..

Real-Time, Seconds-Resolved Measurements of Plasma Methotrexate In Situ in the Living Body.

Dose-limiting toxicity and significant patient-to-patient pharmacokinetic variability often render it difficult to achieve the safe and effective dosing of drugs. This is further compounded by the slow, cumbersome nature of the analytical methods used to monitor patient-specific pharmacokinetics, which inevitably rely on blood draws followed by post-facto laboratory analysis. Motivated by the pressing need for improved "therapeutic drug monitoring", we are developing electrochemical aptamer-based (EAB) sensors, a minimally invasive biosensor architecture that can provide real-time, seconds-resolved measurements of drug levels in situ in the living body. A key advantage of EAB sensors is that they are generalizable to the detection of a wide range of therapeutic agents because they are independent of the chemical or enzymatic reactivity of their targets. Three of the four therapeutic drug classes that have, to date, been shown measurable using in vivo EAB sensors, however, bind to nucleic acids as part of their mode of action, leaving open questions regarding the extent to which the approach can be generalized to therapeutics that do not. Here, we demonstrate real-time, in vivo measurements of plasma methotrexate, an antimetabolite (a mode of action not reliant on DNA binding) chemotherapeutic, following human-relevant dosing in a live rat animal model. By providing hundreds of drug concentration values, the resulting seconds-resolved measurements succeed in defining key pharmacokinetic parameters, including the drug's elimination rate, peak plasma concentration, and exposure (area under the curve), with unprecedented 5 to 10% precision. With this level of precision, we easily identify significant (>2-fold) differences in drug exposure occurring between even healthy rats given the same mass-adjusted methotrexate dose. By providing a real-time, seconds-resolved window into methotrexate pharmacokinetics, such measurements can be used to precisely "individualize" the dosing of this significantly toxic yet vitally important chemotherapeutic.

Antituberculosis Macozinone Extended-Release Tablets To Enhance Bioavailability: a Pilot Pharmacokinetic Study in Beagle Dogs.

Macozinone (MCZ; PBTZ169) is a first-in-class antituberculosis clinical-stage benzothiazinone-based drug candidate. Although its efficacy and safety have been strongly proven in several preclinical and clinical studies, the physicochemical and pharmacokinetic properties specific to MCZ required further optimization. Accordingly, this study aimed to evaluate the pharmacokinetics of MCZ administered as extended-release (ER) tablets F2 and F6 compared to immediate-release (IR) dispersible tablets for oral suspension. Oral absorption of MCZ from ER tablets was significantly different from that of IR tablets after a single oral dose in Beagle dogs in both fasted and fed states. In addition, food directly affects the bioavailability of MCZ from ER tablets but does not affect it from IR tablets. The high values of relative bioavailability of the prolonged-release tablets F2 and F6 compared to the IR tablets may indicate an indirect confirmation of their gastroretentive properties. Taken together, pharmacokinetic parameters have demonstrated that these MCZ oral formulations not just enhance drug bioavailability but may also improve regimen adherence by reducing MCZ dose frequency and reducing the development of drug resistance. IMPORTANCE Macozinone (MCZ) is the newest first-in-class clinical-stage benzothiazinone-based drug candidate for the treatment of tuberculosis. Yet, the extremely low oral bioavailability of MCZ, a major problem in clinical trials, needed to be addressed, and we are pleased to present our attempts to solve this issue. We report that extended-release tablets of MCZ significantly increased key pharmacokinetic parameters in the preclinical setting. We suggest that these MCZ oral formulations not just enhance drug bioavailability but may also improve regimen adherence by reducing MCZ dose frequency and reducing the development of drug resistance.

DDEL-05. PHARMACOKINETICS AND CNS DISTRIBUTION OF A NOVEL ATM INHIBITOR, WSD0628, FOR THE TREATMENT OF BRAIN TUMORS

Abstract The treatment of brain tumors using chemo- and radio-sensitizers may be limited by a lack of effective drug delivery. Radiation and some cytotoxic therapies induce DNA damage, and DNA damage response (DDR) pathways modulate resistance to effective chemo-radiation therapy. Inhibiting DDR pathways by targeting ATM leads to sensitization and enhances cytotoxicity. The purpose of this study is to determine the key pre-clinical pharmacokinetic parameters and mechanisms that influence the CNS delivery of WSD0628, a novel ATM inhibitor. Pharmacokinetics and CNS distribution studies were conducted in FVB wild-type mice following intravenous (IV) and oral (PO) dosing (5 mg/kg). Plasma, brain, and spinal cord samples were harvested after dosing and drug concentrations were measured using LC-MS/MS. The free fraction of WSD0628 was measured in plasma, brain, and spinal cord using rapid equilibrium dialysis. Our results indicate that WSD0628 has a half-life of 4.11 hrs and a high oral bioavailability (0.95). The brain partition coefficient (AUCbrain/AUCplasma, i.e., Kp, brain) is 0.05 and 0.11 after IV and PO dosing, respectively. The free fraction in plasma is 2.01 ± 0.02 % and in brain it is 1.22 ± 0.40 %. The unbound brain partition coefficient (Kpuu brain) is 0.03 and 0.06 after IV and PO dosing, respectively. The differential binding to plasma and brain tissues results in a relatively low Kpuu, a key parameter describing brain penetrability. These data show that WSD0628, a highly potent inhibitor of ATM, reached sufficient concentrations in brain after a single dose of 5 mg/kg to engage ATM over the desired time frame and elicit a response after DNA damage by chemo-radiotherapy. WSD0628 shows promising potential and further evaluations are underway to determine if efflux transporters at the BBB limit its brain distribution.

Can We Predict Clinical Pharmacokinetics of Highly Lipophilic Compounds by Integration of Machine Learning or In Vitro Data into Physiologically Based Models? A Feasibility Study Based on 12 Development Compounds.

While high lipophilicity tends to improve potency, its effects on pharmacokinetics (PK) are complex and often unfavorable. To predict clinical PK in early drug discovery, we built human physiologically based PK (PBPK) models integrating either (i) machine learning (ML)-predicted properties or (ii) discovery stage in vitro data. Our test set was composed of 12 challenging development compounds with high lipophilicity (mean calculated log P 4.2), low plasma-free fraction (50% of compounds with fu,p < 1%), and low aqueous solubility. Predictions focused on key human PK parameters, including plasma clearance (CL), volume of distribution at steady state (Vss), and oral bioavailability (%F). For predictions of CL, the ML inputs showed acceptable accuracy and slight underprediction bias [an average absolute fold error (AAFE) of 3.55; an average fold error (AFE) of 0.95]. Surprisingly, use of measured data only slightly improved accuracy but introduced an overprediction bias (AAFE = 3.35; AFE = 2.63). Predictions of Vss were more successful, with both ML (AAFE = 2.21; AFE = 0.90) and in vitro (AAFE = 2.24; AFE = 1.72) inputs showing good accuracy and moderate bias. The %F was poorly predicted using ML inputs [average absolute prediction error (AAPE) of 45%], and use of measured data for solubility and permeability improved this to 34%. Sensitivity analysis showed that predictions of CL limited the overall accuracy of human PK predictions, partly due to high nonspecific binding of lipophilic compounds, leading to uncertainty of unbound clearance. For accurate predictions of %F, solubility was the key factor. Despite current limitations, this work encourages further development of ML models and integration of their results within PBPK models to enable human PK prediction at the drug design stage, even before compounds are synthesized. Further evaluation of this approach with more diverse chemical types is warranted.

DDEL-01. The role of key pharmacodynamic and pharmacokinetic parameters in drug response prediction of pediatric tumors in the precision oncology study INFORM

Abstract INTRODUCTION: The INFORM (INdividualized Therapy FOr Relapsed Malignancies in Childhood) study is a European pediatric precision oncology program. Using state of the art molecular assays, INFORM aims for identification of targetable genetic alterations, matching drugs and clinical trials. High evidence targets were associated with doubling of progression free survival when patients received a matching drug. However, the fraction of tumors with high evidence drug targets remains low requiring functional layers of information such as drug sensitivity profiling. The aim of this project is to identify and investigate the role of key pharmacodynamic and pharmacokinetic parameters to improve the predictivity of ex vivo drug response of pediatric tumors. METHODS: Positive control cell lines harboring specific mutations (n=7) and primary tumors (n=121) from INFORM, including 10% ependymomas, 7% high grade gliomas, 5% neuroblastomas and 4% medulloblastomas, were profiled ex vivo using a library of n=76 clinically relevant oncology drugs in a 384 well plate format. Metabolic activity was measured after 72h of treatment. Quality control (QC) was done using the robust z-factor, correlation of replicates and mean negative control. Hit selection was based on maximum percentage inhibition, normalized AUC metric (DSSasym) and maximum serum concentration (Cmax) of the drug. Clinical follow-up was collected using a questionnaire. RESULTS: A linear mixed model revealed the DSSasym to be the strongest pharmacodynamic parameter in drug prediction in cell lines. Drug screens of n=105 INFORM cases passed QC. Application of the filtering parameters resulted in prediction of n=1-16 drugs/case (min-max). A data base of published pediatric pharmacokinetic parameters of the drug library was generated. Analysis of predictive parameters and clinical follow-up of clinical samples is ongoing. CONCLUSION: Including pharmacodynamic as well as clinical pharmacokinetic parameters is paramount to identify potentially clinically active compounds from ex vivo drug screen data. Further algorithm development is warranted.

Quality consistency evaluation between dispensing granules and traditional decoction of Gardeniae Fructus based on chemical similarity and bioequivalence

Dispensing granules of Chinese herbal medicines are gaining more and more recognition. Despite this, how to evaluate the quality consistency between traditional decoction and its corresponding dispensing granules is a challenging task. In this work, we attempted to propose a comprehensive strategy through in vitro and in vivo comparisons to overcome this challenge, taking Gardeniae Fructus as a typical case. On one hand, HPLC fingerprinting and multi-component quantification were performed to evaluate chemical similarity. On the other hand, pharmacokinetic profiling was conducted to estimate bioequivalence in terms of concentration-time curve and key pharmacokinetic parameters. The in vitro and in vivo comparison results demonstrated that there were no significant differences between these two dosage forms. This proposed strategy is applicable not only for quality consistency evaluation between dispensing granules and traditional decoction but also for broader application scenarios.