Development of a Web Application for Simulating Plasma Drug Concentrations in Patients with Zolpidem Intoxication.

Zolpidem is a widely prescribed hypnotic Z-drug used to treat short-term insomnia. However, a growing number of individuals intentionally overdose on these drugs. This study aimed to develop a predictive tool for physicians to assess patients with zolpidem overdose. A population pharmacokinetic (PK) model was established using digitized data obtained from twenty-three healthy volunteers after a single oral administration of zolpidem. Based on the final PK model, a web application was developed using open-source R packages such as rxode2, nonmem2rx, and shiny. The final model was a one-compartment model with first-order absorption and elimination with PK parameters, including clearance (CL, 16.9 L/h), absorption rate constant (Ka, 5.41 h-1), volume of distribution (Vd, 61.7 L), and lag time (ALAG, 0.394 h). Using the established population PK model in the current study, we developed a web application that enables users to simulate plasma zolpidem concentrations and visualize their profiles. This user-friendly web application may provide essential clinical information to physicians, ultimately helping in the management of patients with zolpidem intoxication.

Pharmacokinetic Interactions Between Bazedoxifene and Cholecalciferol: An Open-Label, Randomized, Crossover Study in Healthy Male Volunteers.

Purpose: The combined administration of bazedoxifene, a tissue-selective estrogen receptor modulator, and cholecalciferol can be a promising therapeutic option for postmenopausal osteoporosis patients. This study aimed to examine the pharmacokinetic interactions between these two drugs and the tolerability of their combined administration in healthy male subjects. Patients and Methods: Thirty male volunteers were randomly assigned to one of the six sequences comprised of three treatments: bazedoxifene 20 mg monotherapy, cholecalciferol 1600 IU monotherapy, and combined bazedoxifene and cholecalciferol therapy. For each treatment, a single dose of the investigational drug(s) was administered orally, and serial blood samples were collected to measure the plasma concentrations of bazedoxifene and cholecalciferol. Pharmacokinetic parameters were calculated using the non-compartmental method. The point estimate and 90% confidence interval (CI) of the geometric mean ratio (GMR) were obtained to compare the exposures of combined therapy and monotherapy. The pharmacokinetic parameters compared were the maximum plasma concentration (Cmax) and the area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUClast). The safety and tolerability of the combined therapy were assessed in terms of the frequency and severity of adverse events (AEs). Results: For bazedoxifene, the GMR (90% CI) of the combined therapy to monotherapy was 1.044 (0.9263-1.1765) for Cmax and 1.1329 (1.0232-1.2544) for AUClast. For baseline-adjusted cholecalciferol, the GMR (90% CI) of the combined therapy to monotherapy was 0.8543 (0.8005-0.9117) for Cmax and 0.8056 (0.7445-0.8717) for AUClast. The frequency of AEs observed was not significantly different between the combined therapy and monotherapy, and their severity was mild in all cases. Conclusion: A mild degree of pharmacokinetic interaction was observed when bazedoxifene and cholecalciferol were administered concomitantly to healthy male volunteers. This combined therapy was well tolerated at the dose levels used in the present study.

Establishing Rationale for the Clinical Development of Cell Therapy Products: Consensus between Risk and Benefit.

Despite long-term research achievements, the development of cell therapy (CT) products remains challenging. This is because the risks experienced by the subject and therapeutic effects in the clinical trial stage are unclear due to the various uncertainties of CT when administered to humans. Nevertheless, as autologous cell products for systemic administration have recently been approved for marketing, CT product development is accelerating, particularly in the field of unmet medical needs. The human experience of CT remains insufficient compared with other classes of pharmaceuticals, while there are countless products for clinical development. Therefore, for many sponsors, understanding the rationale of human application of an investigational product based on the consensus and improving the ability to apply it appropriately for CT are necessary. Thus, defining the level of evidence for safety and efficacy fundamentally required for initiating the clinical development and preparing it using a reliable method for CT. Furthermore, the expertise should be strengthened in the design of the first-in-human trial, such as the starting dose and dose-escalation plan, based on a sufficiently acceptable rationale. Cultivating development professionals with these skills will increase the opportunity for more candidates to enter the clinical development phase.

Comparison of Pharmacodynamics between Tegoprazan and Dexlansoprazole Regarding Nocturnal Acid Breakthrough: A Randomized Crossover Study.

Background/Aims: Tegoprazan, a novel potassium-competitive acid blocker, is expected to overcome the limitations of proton pump inhibitors and effectively control nocturnal acid breakthrough. To evaluate the pharmacodynamics of tegoprazan versus dexlansoprazole regarding nocturnal acid breakthrough in healthy subjects. Methods: In a randomized, open-label, single-dose, balanced incomplete block crossover study, 24 healthy male volunteers were enrolled and randomized to receive oral tegoprazan (50, 100, or 200 mg) or dexlansoprazole (60 mg) during each of two administration periods, separated by a 7- to 10-day washout period. Blood samples were collected for pharmacokinetic parameter analysis; gastric monitoring was performed for pharmacodynamic parameter evaluation. Results: All 24 subjects completed the study. Average maximum plasma concentration, area under the plasma concentration-time curve, and mean time with gastric pH >4 and pH >6 for tegoprazan demonstrated dose-dependent incremental increases. All the tegoprazan groups reached mean pH ≥4 within 2 hours, whereas the dexlansoprazole group required 7 hours after drug administration. Based on pharmacodynamic parameters up to 12 hours after evening dosing, 50, 100, and 200 mg of tegoprazan presented a stronger acid-suppressive effect than 60 mg of dexlansoprazole. Moreover, the dexlansoprazole group presented a comparable acid-suppressive effect with the tegoprazan groups 12 hours after dosing. Conclusions: All the tegoprazan groups demonstrated a significantly faster onset of gastric pH increase and longer holding times above pH >4 and pH >6 up to 12 hours after evening dosing than the dexlansoprazole group.

Pharmacokinetic properties of a new sustained-release pregabalin tablet in subjects with reduced renal function.

A new sustained-release (SR) pregabalin tablet, YHD1119, was formulated for once-daily dosing. In the current study, we aimed to evaluate the pharmacokinetics of YHD1119 tablets in patients with reduced renal function. Subjects were grouped by creatinine clearance: > 60 mL/min/1.73m2 (Cohort A) and 30-60 mL/min/1.73m2 (Cohort B). Eight subjects in Cohort A received a YHD1119 75 mg tablet (Y75T) and a YHD1119 150 mg tablet (Y150T) in each period, and eight subjects in Cohort B received a Y75T. Non-compartment analysis and population pharmacokinetic analysis using a one-compartment model with first-order elimination and first-order absorption with lag time were performed. Sixteen subjects completed the study. The geometric mean ratio (GMR) (90% confidence intervals [CI]) for maximum concentration (Cmax), and area under the concentration-time profile from 0 to the last measurable time (AUClast) after Y75T of Cohort B to those of Y75T of Cohort A were 1.2273 (1.0245-1.4701), and 2.4146 (1.8142-3.2138), respectively. The GMR (90% CI) for Cmax, and AUClast after Y75T of Cohort B to those of Y150T of Cohort A were 0.6476 (0.5229-0.8021), and 1.1471 (0.8418-1.5632), respectively. Simulated steady-steady pregabalin concentrations after once-daily Y75T dosing in subjects with eGFR 45 mL/min/1.73 m2 were within the range of steady-state concentrations simulated after once-daily Y150T dosing in subjects with eGFR 90 mL/min/1.73 m2. The total pregabalin exposure of Y75T in patients with moderate renal impairment was comparable with that of Y150T in subjects with near-normal renal function. Trial Registration: ClinicalTrials.gov Identifier: NCT05012436.

Urinary Profile of Endogenous Gamma-Hydroxybutyric Acid and its Biomarker Metabolites in Healthy Korean Females: Determination of Age-Dependent and Intra-Individual Variability and Identification of Metabolites Correlated With Gamma-Hydroxybutyric Acid.

Gamma-hydroxybutyric acid (GHB), used as a therapeutic and an illegal anesthetic, is a human neurotransmitter produced during gamma-aminobutyric acid (GABA) biosynthesis and metabolism. Potential biomarker metabolites of GHB intoxication have been identified previously; however, reference concentrations have not been set due to the lack of clinical study data. Urinary profiling of endogenous GHB and its biomarker metabolites in urine samples (n = 472) of 206 healthy females was performed based on differences in age and time of sample collection using liquid chromatography-tandem mass spectrometry following validation studies. The unadjusted and creatinine-adjusted urinary concentrations ranges were obtained after urinary profiling. The creatinine-adjusted concentrations of glutamic and succinic acids and succinylcarnitine significantly increased, whereas that of glycolic acid significantly decreased with advancing age. Significant inter-day variation of GABA concentration and intra-day variation of 3,4-dihydroxybutyric acid and succinylcarnitine concentrations were observed. The urinary concentrations of 2,4-dihydroxybutyric acid, succinic acid, and 3,4-dihydroxybutyric acid showed the highest correlation with that of GHB. Data from this study suggest population reference limits to facilitate clinical and forensic decisions related to GHB intoxication and could be useful for identification of biomarkers following comparison with urinary profiles of GHB-administered populations.

DallphinAtoM: Physiologically based pharmacokinetics software predicting human PK parameters based on physicochemical properties, in vitro and animal in vivo data.

BACKGROUND AND OBJECTIVES: In silico experiments and simulations using physiologically based pharmacokinetic (PBPK) and allometric approaches have played an important role in pharmaceutical research and drug development. These methods integrate diverse data from preclinical and clinical development, and have been widely applied to in vitro-in vivo extrapolation (IVIVE) of absorption, distribution, metabolism, and excretion (ADME). METHODS: To develop a user-friendly open tool predicting human PK, we assessed various references on PBPK and allometric methods published so far. They were integrated into a software system named "DallphinAtoM" (Drugs with ALLometry and PHysiology Inside-Animal to huMan), which has a user-friendly platform that can handle complex PBPK models and allometric models with a relatively small amount of essential information of the drug. The models of DallphinAtoM support the integration of data gained during the nonclinical development phase, enable translation from animal to human, and allow the prediction of concentration-time profiles with predicted PK parameters. RESULTS: We presented two illustrative applications using DallphinAtoM: (1) human PK simulation of an orally administered drug using PBPK method; and (2) simulation of intravenous infusion following a two-compartment model using the allometric scaling method. CONCLUSIONS: We conclude that this is a straightforward and transparent tool allowing fast and reliable human PK simulation based on the latest knowledge on biochemical processes and physiology and provides valuable information for decision making during the early-phase drug development.

An experience on the model-based evaluation of pharmacokinetic drug-drug interaction for a long half-life drug.

Fixed-dose combinations development requires pharmacokinetic drugdrug interaction (DDI) studies between active ingredients. For some drugs, pharmacokinetic properties such as long half-life or delayed distribution, make it difficult to conduct such clinical trials and to estimate the exact magnitude of DDI. In this study, the conventional (non-compartmental analysis and bioequivalence [BE]) and modelbased analyses were compared for their performance to evaluate DDI using amlodipine as an example. Raw data without DDI or simulated data using pharmacokinetic models were compared to the data obtained after concomitant administration. Regardless of the methodology, all the results fell within the classical BE limit. It was shown that the model-based approach may be valid as the conventional approach and reduce the possibility of DDI overestimation. Several advantages (i.e., quantitative changes in parameters and precision of confidence interval) of the model-based approach were demonstrated, and possible application methods were proposed. Therefore, it is expected that the model-based analysis is appropriately utilized according to the situation and purpose.

Effect of Food on the Pharmacokinetics and Pharmacodynamics of a Single Oral Dose of Tegoprazan.

PURPOSE: Tegoprazan is a potassium-competitive acid blocker (P-CAB) that is designed to treat acid-related diseases through a fundamentally different mechanism than that of proton pump inhibitors (PPIs). Because PPIs inhibit only activated parietal cell H+/K+ adenosine triphosphatase, stimulation of parietal cells by a meal is necessary for optimal results. In contrast, P-CABs can inactivate proton pumps without acid activation and bind to both activated and inactivated adenosine triphosphatase. This study evaluates the effect of food consumption on the pharmacokinetic and pharmacodynamic properties of tegoprazan after a single oral dose in healthy men. METHODS: In this open-label, 2-period crossover study, 24 healthy men were randomized to 1 of 2 treatment sequence groups: administration of tegoprazan under the fasting condition and administration of tegoprazan under the fed condition. The dosing periods of both sequence groups were separated by a washout period of 7 days. At each dosing period, the participants received a single dose of 200 mg of tegoprazan followed by pharmacokinetic and pharmacodynamic analysis. FINDINGS: After the oral administration of 200 mg tegoprazan, the Cmax was decreased and delayed under the fed condition compared with that of the fasting condition. However, no significant differences were observed in the AUC and the time of gastric acid suppression (inhibition of integrated acidity) during 24 hours. IMPLICATIONS: The pharmacokinetic and pharmacodynamic properties of tegoprazan are independent of food effect; thus, tegoprazan could be administered regardless of the timing of food consumption in patients. ClinicalTrials.gov identifier: NCT01830309.

First-in-Human, Double-Blind, Randomized Controlled Trial of an Oral Dose of GnRH Antagonist TU2670 in Healthy Women.

OBJECTIVE: To evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of TU2670, a novel orally active, nonpeptide gonadotropin-releasing hormone (GnRH) antagonist administered to healthy female participants. METHODS: This was a first-in-human, multicenter, phase 1, randomized, double-blind, placebo-controlled, single-dose ascending trial that took place in multiple medical centers. A total of 16 healthy premenopausal women (23 to 45 years of age) were randomized and received 20, 40, 80, and 160 mg TU2670 (GnRH antagonist) or placebo 7 days (±1 day) after the onset of menstrual bleeding. We performed a noncompartmental analysis for pharmacokinetic parameters and calculated relative minimum concentration values (Cmin, % Baseline) of serum pharmacodynamic (PD) markers (luteinizing hormone [LH], follicle-stimulating hormone [FSH], and estradiol). RESULTS: There were no significant differences among treatments with respect to vital signs, electrocardiography, adverse events, ovulation test results, and ultrasonography. The median Tmax of TU2670 occurred 0.75 to 1.00 hours after dosing, and concentrations then declined, with a mean apparent half-life (t1/2) of 3.0 to 5.9 hours. AUClast (17.7-417.9 ng·h/mL) and Cmax (8.1-95.4 ng/mL) increased in a dose-dependent manner. The PD analysis after a single administration of TU2670 revealed dose-dependent suppression of LH, FSH, and estradiol. Maximal suppression of the pre-dose baseline (%) was 58% to 82% at 6 to 8 hours for LH, 28% to 39% at 6 to 12 hours for FSH, and 34% to 82% at 12 to 24 hours for estradiol. CONCLUSION: The single administration of TU2670 in healthy premenopausal women was well tolerated and resulted in the dose-dependent suppression of LH, FSH, and estradiol, suggesting rapid and significant inhibition of pituitary and ovarian hormones.

First-in-Human Evaluation of the Safety, Tolerability, and Pharmacokinetics of a Neuroprotective Poly (ADP-ribose) Polymerase-1 Inhibitor, JPI-289, in Healthy Volunteers.

BACKGROUND: Poly (ADP-ribose) polymerase-1 (PARP-1) inhibitor has therapeutic potential for acute ischemic stroke by suppressing microglial activation and facilitating neuroprotection. In this first-in-human study, we investigate the safety, tolerability and pharmacokinetics (PK) of JPI-289 in healthy male volunteers. SUBJECTS AND METHODS: In single ascending dose (SAD) study, 35, 75, 150, 300, 600 mg JPI-289 or placebo was infused intravenously over 30 minutes to 40 subjects. In multiple ascending dose (MAD) study, 150, 300, 450 mg JPI-289 or placebo was infused over 1 hour every 12 hours to each of 24 subjects for 3.5 days (7 times). The plasma and urine concentrations of JPI-289 and its metabolites were determined. RESULTS: In the SAD study, AUClast and Cmax tended to increase supra-proportionally especially at higher doses in SAD study. However, Cmax showed dose-proportionality in the range of 75-600mg. JPI-289 reached a mean Tmax within 0.50 hour after dosing and a mean elimination half-life (t1/2) was 2.18 to 3.21 hours. In the MAD study, observed accumulation index ranged from 1.52 to 1.76. The effective half-life of JPI-289 was 1.88 to 3.05 hours, indicating that the plasma JPI-289 concentration rapidly reaches steady state. % recovered of JPI-289 measured in urine was 1.59-9.05%. In both studies, concentration of metabolites was less than 10% of JPI-289. Adverse events reported in the study were all mild in intensity and resolved without any sequelae. CONCLUSION: The tolerable dose ranges and pharmacokinetic characteristics of JPI-289 evaluated in these studies will be useful in further clinical development of JPI-289.

Usefulness of Bnet, a Simple Linear Metric in Discerning Torsades De Pointes Risks in 28 CiPA Drugs.

The Comprehensive in vitro Proarrhythmia Assay (CiPA) project suggested the torsade metric score (TMS) which requires substantial computing resources as a useful biomarker to predict proarrhythmic risk from human ether-à-go-go-related gene (hERG) and a few other ion channel block data. The TMS was useful to predict low TdP risks of drugs blocking Na+ (ranolazine) and Ca2+ (verapamil) channels as well as the hERG channel. However, Mistry asserted that the simple linear metric, Bnet reflecting net blockade of a few influential ion channels has similar predictive power. Here we compared the predictability of Bnet and TMS for the 12 training and 16 validation CiPA drugs which were pre-classified into three categories according to the known TdP risks (low, intermediate, and high risk) by CiPA. Bnet at 5×Cmax (Bnet5×Cmax) was calculated using the ion-channel IC50 and Hill coefficients of CiPA drugs collected from previous reports by the CiPA team and others. The receiver operating characteristic curve area under curve (ROC AUC) values for TMS and Bnet5×Cmax as performance metrics in discerning low versus intermediate/high risk categories for the 28 CiPA drugs were similar. However, Bnet5×Cmax was much inferior to TMS at discerning between intermediate- and high-risk drugs. Dynamic Bnet, which used in silico hERG dynamic parameters unlike conventional Bnet, improved the misspecification. Thus, we propose that Bnet5×Cmax is used for quick screening of TdP risks of drug candidates and if the "intermediate/high" risk is predicted by Bnet5×Cmax, in silico approaches, such as dynamic Bnet or TMS, may be further considered.

Randomised clinical trial: safety, tolerability, pharmacokinetics, and pharmacodynamics of single and multiple oral doses of tegoprazan (CJ-12420), a novel potassium-competitive acid blocker, in healthy male subjects.

BACKGROUND: Tegoprazan (CJ-12420) is a potassium-competitive acid blocker (P-CAB) with therapeutic potential for gastro-oesophageal reflux disease (GERD) by reversibly suppressing gastric H+ /K+ -ATPase. AIMS: To investigate the safety, tolerability, pharmacokinetics and pharmacodynamics of tegoprazan METHODS: A phase I, randomised, double-blind and placebo-controlled clinical trial was conducted in 56 healthy male subjects without Helicobacter pylori infection. In the single ascending dose study, 50, 100, 200 and 400 mg tegoprazan were administered to 32 subjects. In the multiple ascending dose study, 100 and 200 mg tegoprazan were administered every 24 hours to each of the eight subjects for 7 days. In the comparative pharmacodynamics study, 40 mg esomeprazole was administered to eight subjects every 24 hours for 7 days. The assessment included safety, tolerability, pharmacodynamics through monitoring of 24-hour gastric pH and pharmacokinetics of tegoprazan in plasma and urine. RESULTS: Tegoprazan was generally well tolerated. Most adverse events reported in the study were mild in intensity and resolved without any sequelae. Exposure to tegoprazan increased in a dose-proportional manner. Multiple dosing with tegoprazan showed no accumulation in plasma on day 7. The pharmacodynamic analysis revealed that tegoprazan showed rapid, dose-dependent gastric acid suppression. CONCLUSIONS: Tegoprazan was well tolerated and showed rapid and potent gastric acid suppression. This supports the further development of tegoprazan as a treatment for acid-related disorders.

Pharmacokinetic and Pharmacodynamic Modeling and Simulation Analysis of CTB-001, a Recently Developed Generic of Bivalirudin.

PURPOSE: CTB-001, a recently developed generic version of bivalirudin, an FDA-approved anticoagulant used for prophylaxis and treatment of cardiovascular diseases, has shown good efficacy and safety in clinical trials. We characterized the pharmacokinetics (PK) and pharmacodynamics (PD) of CTB-001 by modeling and simulation analysis. METHODS: PK/PD data were collected from a randomized, double-blind, placebo-controlled, single-dose, dose-escalation phase 1 study conducted in 24 healthy Korean male subjects. PK/PD analysis was conducted sequentially by nonlinear mixed-effects modeling implemented in NONMEM®. Monte-Carlo simulations were conducted for PK, activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). RESULTS: The CTB-101 PK was best described by a three-compartment linear model with a saturable binding peripheral compartment. All PD endpoints showed dose-response relationship, and their changes over time paralleled those of CTB-101 concentrations. A simple maximum effect model best described the aPTT, PT in INR, PT in seconds, and TT, whereas an inhibitory simple maximum effect model best described PT in percentages. The maximum duration of effect of CTB-001 on aPTT prolongation was 52.1 s. CONCLUSIONS: The modeling and simulation analysis well-characterized the PK and PD of CTB-001 in healthy Koreans, which will be valuable for identifying optimal dosing regimens of CBT-001.

Single-dose Intravenous Safety, Tolerability, and Pharmacokinetics and Absolute Bioavailability of LCB01-0371.

PURPOSE: LCB01-0371 is a novel broad-spectrum oxazolidinone antibacterial agent under investigation for the treatment of infection by gram-positive pathogens, including methicillin-resistant Staphylococcus aureus. This study evaluated the safety, tolerability, and pharmacokinetics of LCB01-0371 after a single intravenous (IV) infusion and determined its absolute oral bioavailability at a therapeutic dose of 800 mg. METHODS: This study was conducted in 2 parts. The first part was a single-blind, placebo-controlled, escalating single IV dose study (200, 400, 800, and 1200 mg) of LCB01-0371 via 2 different infusion regimens (250 mL over 60 min or 150 mL over 30 min) in 36 healthy male volunteers. The second part was an open-label, 2-way crossover design study in which 8 subjects were randomly assigned to 1 of 2 sequences of a single oral (800 mg) or IV (400 mg) administration of LCB01-0371. Safety assessments were conducted at regular intervals. Blood and urine were serially sampled, and drug concentrations were measured for up to 24 h to calculate pharmacokinetic parameters. FINDINGS: LCB01-0371 after IV administration was generally safe and well tolerated up to 800 mg regardless of the infusion regimen. Adverse events were mild, excluding nausea at the highest dose, and resolved spontaneously. After a single IV administration, LCB01-0371 exhibited linear pharmacokinetic properties over the range of 200-800 mg. The elimination t1/2, volume of distribution, and clearance ranged from 1.48 to 1.68 h, 57.74-76.72 L, and 33.17-43.31 L/h, respectively, and they remained unchanged over the corresponding dose range. Cmax, AUC0-last, and AUC0-∞ increased in a dose-dependent manner. The dose-normalized total exposure after single PO and IV dosing were equivalent, with 90% CIs of the geometric least squares mean ratio of 86.6%-110% for AUC0-last and 86.6%-111% for AUC0-∞. The dose-normalized Cmax was not equivalent between oral and IV dosing, with a 90% CI of the geometric least squares mean ratio of 50.0%-105%. The absolute oral bioavailability of LCB01-0371 after a single 800-mg dose was 99.75%. IMPLICATIONS: After a single IV administration, LCB01-0371 was well tolerated in healthy volunteers at doses up to 800 mg, and it exhibited linear pharmacokinetic properties. The comparable total systemic exposure between IV and oral administration supports the ability to switch administration routes without a need for dose adjustment. ClinicalTrials.gov identifier: NCT02882789.

Development of R packages: 'NonCompart' and 'ncar' for noncompartmental analysis (NCA).

Noncompartmental analysis (NCA) is a primary analytical approach for pharmacokinetic studies, and its parameters act as decision criteria in bioequivalent studies. Currently, NCA is usually carried out by commercial softwares such as WinNonlin®. In this article, we introduce our newly-developed two R packages, NonCompart (NonCompartmental analysis for pharmacokinetic data) and ncar (NonCompartmental Analysis for pharmacokinetic Report), which can perform NCA and produce complete NCA reports in both pdf and rtf formats. These packages are compatible with CDISC (Clinical Data Interchange Standards Consortium) standard as well. We demonstrate how the results of WinNonlin® are reproduced and how NCA reports can be obtained. With these R packages, we aimed to help researchers carry out NCA and utilize the output for early stages of drug development process. These R packages are freely available for download from the CRAN repository.

Erratum: Development of R packages: 'NonCompart' and 'ncar' for noncompartmental analysis (NCA).

[This corrects the article on p. 10 in vol. 26.].

Prediction of the human in vivo antiplatelet effect of S- and R-indobufen using population pharmacodynamic modeling and simulation based on in vitro platelet aggregation test.

Indobufen (Ibustrin®), a reversible inhibitor of platelet aggregation, exists in two enantiomeric forms in 1:1 ratio. Here, we characterized the anti-platelet effect of S- and R-indobufen using response surface modeling using NONMEM® and predicted the therapeutic doses exerting the maximal efficacy of each enantioselective S- and R-indobufen formulation. S- and R-indobufen were added individually or together to 24 plasma samples from drug-naïve healthy subjects, generating 892 samples containing randomly selected concentrations of the drugs of 0-128 mg/L. Collagen-induced platelet aggregation in platelet-rich plasma was determined using a Chrono-log Lumi-Aggregometer. Inhibitory sigmoid Imax model adequately described the anti-platelet effect. The S-form was more potent, whereas the R-form showed less inter-individual variation. No significant interaction was observed between the two enantiomers. The anti-platelet effect of multiple treatments with 200 mg indobufen twice daily doses was predicted in the simulation study, and the effect of S- or R-indobufen alone at various doses was predicted to define optimal dosing regimen for each enantiomer. Simulation study predicted that 200 mg twice daily administration of S-indobufen alone will produce more treatment effect than S-and R-mixture formulation. S-indobufen produced treatment effect at lower concentration than R-indobufen. However, inter-individual variation of the pharmacodynamic response was smaller in R-indobufen. The present study suggests the optimal doses of R-and S-enantioselective indobufen formulations in terms of treatment efficacy for patients with thromboembolic problems. The proposed methodology in this study can be applied to the develop novel enantio-selective drugs more efficiently.

Caffsim: simulation of plasma caffeine concentrations implemented as an R package and Web-applications.

Caffeine is a naturally-occurring central nervous system stimulant found in plant constituents including coffee, cocoa beans, and tea leaves. Consumption of caffeine through imbibing caffeinated drinks is rapidly growing among children, adolescents, and young adults, who tend to be more caffeine-sensitive than the rest of the general public; consequently, caffeine-related toxicities among these groups are also growing in number. However, a quantitative and interactive tool for predicting the plasma caffeine concentration that may lead to caffeine intoxication has yet to be developed. Using the previously established population-pharmacokinetic model, we developed "caffsim" R package and its web-based applications using Shiny and EDISON (EDucation-research Integration through Simulation On the Net). The primary aim of the software is to easily predict and calculate plasma caffeine concentration and pharmacokinetic parameters and visualize their changes after single or multiple ingestions of caffeine. The caffsim R package helps understand how plasma caffeine concentration changes over time and how long toxic concentration of caffeine can last in caffeine-sensitive groups. It may also help clinical evaluation of relationship between caffeine intake and toxicities when suspicious acute symptoms occur.

Comprehensive immunophenotyping of cerebrospinal fluid cells in patients with neuroimmunological diseases.

We performed unbiased, comprehensive immunophenotyping of cerebrospinal fluid (CSF) and blood leukocytes in 221 subjects referred for the diagnostic work-up of neuroimmunological disorders to obtain insight about disease-specific phenotypes of intrathecal immune responses. Quantification of 14 different immune cell subsets, coupled with the assessment of their activation status, revealed physiological differences between intrathecal and systemic immunity, irrespective of final diagnosis. Our data are consistent with a model where the CNS shapes intrathecal immune responses to provide effective protection against persistent viral infections, especially by memory T cells, plasmacytoid dendritic cells, and CD56(bright) NK cells. Our data also argue that CSF immune cells do not simply reflect cells recruited from the periphery. Instead, they represent a mixture of cells that are recruited from the blood, have been activated intrathecally and leave the CNS after performing effector functions. Diagnosis-specific differences provide mechanistic insight into the disease process in the defined subtypes of multiple sclerosis (MS), neonatal onset multisystem inflammatory disease, and Aicardi-Goutières syndrome. This analysis also determined that secondary-progressive MS patients are immunologically closer to relapsing-remitting patients as compared with patients with primary-progressive MS. Because CSF immunophenotyping captures the biology of the intrathecal inflammatory processes, it has the potential to guide optimal selection of immunomodulatory therapies in individual patients and monitor their efficacy. Our study adds to the increasing number of publications that demonstrate poor correlation between systemic and intrathecal inflammatory biomarkers in patients with neuroimmunological diseases and stresses the importance of studying immune responses directly in the intrathecal compartment.