Transforming clinical trials: the emerging roles of large language models.

Clinical trials are essential for medical research, but they often face challenges in matching patients to trials and planning. Large language models (LLMs) offer a promising solution, signaling a transformative shift in the field of clinical trials. This review explores the multifaceted applications of LLMs within clinical trials, focusing on five main areas expected to be implemented in the near future: enhancing patient-trial matching, streamlining clinical trial planning, analyzing free text narratives for coding and classification, assisting in technical writing tasks, and providing cognizant consent via LLM-powered chatbots. While the application of LLMs is promising, it poses challenges such as accuracy validation and legal concerns. The convergence of LLMs with clinical trials has the potential to revolutionize the efficiency of clinical trials, paving the way for innovative methodologies and enhancing patient engagement. However, this development requires careful consideration and investment to overcome potential hurdles.

Evaluation of pharmacokinetic drug-drug interaction between tegoprazan and clarithromycin in healthy subjects.

Tegoprazan is a novel potassium-competitive acid blocker that treats gastric acid-related diseases. Clarithromycin was widely used as one of various regimens for eradicating Helicobacter pylori. This study compared the pharmacokinetic and safety profile of tegoprazan and clarithromycin between combination therapy and monotherapy to evaluate the potential drug-drug interaction. An open-label, randomized, 6-sequence, 3-period crossover study was conducted in 24 healthy subjects. According to the assigned sequence, the subject was administered the assigned treatment during 5 days in each period. PK parameters of tegoprazan and clarithromycin administered in combination were compared with those of the respective monotherapies. The co-administration of tegoprazan with clarithromycin increased maximum steady-state plasma concentration (Css,max) and area under the plasma concentration-time curve in dosing interval at steady-state (AUCss,tau) of tegoprazan (1.6-fold in Css,max and 2.5-fold in AUCss,tau) and M1 (2.0-fold in Css,max, 2.5-fold in AUCss,tau) than tegoprazan alone. The Css,max and AUCss,tau of 14-hydroxyclarithromycin increased 1.8- and 2.0-fold in co-administration, respectively. The AUCss.tau of clarithromycin was slightly increased in co-administration, but Css,max was not changed. Combination of tegoprazan and clarithromycin and those of the respective monotherapies were tolerated in 24 healthy subjects. There may exist drug interaction that lead to reciprocal increase in plasma drug concentrations when tegoprazan and clarithromycin were administrated in combination and no safety concerns were raised. It is suggested that an in-depth analysis of the concentration-response relationship is necessary to determine whether these concentration changes warrant clinical action. Trial Registration: ClinicalTrials.gov Identifier: NCT02052336.

Development of a population pharmacokinetic model of pyrazinamide to guide personalized therapy: impacts of geriatric and diabetes mellitus on clearance.

Objectives: This study was performed to develop a population pharmacokinetic model of pyrazinamide for Korean tuberculosis (TB) patients and to explore and identify the influence of demographic and clinical factors, especially geriatric diabetes mellitus (DM), on the pharmacokinetics (PK) of pyrazinamide (PZA). Methods: PZA concentrations at random post-dose points, demographic characteristics, and clinical information were collected in a multicenter prospective TB cohort study from 18 hospitals in Korea. Data obtained from 610 TB patients were divided into training and test datasets at a 4:1 ratio. A population PK model was developed using a nonlinear mixed-effects method. Results: A one-compartment model with allometric scaling for body size effect adequately described the PK of PZA. Geriatric patients with DM (age >70 years) were identified as a significant covariate, increasing the apparent clearance of PZA by 30% (geriatric patients with DM: 5.73 L/h; others: 4.50 L/h), thereby decreasing the area under the concentration-time curve from 0 to 24 h by a similar degree compared with other patients (geriatric patients with DM: 99.87 µg h/mL; others: 132.3 µg h/mL). Our model was externally evaluated using the test set and provided better predictive performance compared with the previously published model. Conclusion: The established population PK model sufficiently described the PK of PZA in Korean TB patients. Our model will be useful in therapeutic drug monitoring to provide dose optimization of PZA, particularly for geriatric patients with DM and TB.

Multimodal plasma metabolomics and lipidomics in elucidating metabolic perturbations in tuberculosis patients with concurrent type 2 diabetes.

Type 2 diabetes mellitus (DM) poses a major burden for the treatment and control of tuberculosis (TB). Characterization of the underlying metabolic perturbations in DM patients with TB infection would yield insights into the pathophysiology of TB-DM, thus potentially leading to improvements in TB treatment. In this study, a multimodal metabolomics and lipidomics workflow was applied to investigate plasma metabolic profiles of patients with TB and TB-DM. Significantly different biological processes and biomarkers in TB-DM vs. TB were identified using a data-driven, knowledge-based framework. Changes in metabolic and signaling pathways related to carbohydrate and amino acid metabolism were mainly captured by amide HILIC column metabolomics analysis, while perturbations in lipid metabolism were identified by the C18 metabolomics and lipidomics analysis. Compared to TB, TB-DM exhibited elevated levels of bile acids and molecules related to carbohydrate metabolism, as well as the depletion of glutamine, retinol, lysophosphatidylcholine, and phosphatidylcholine. Moreover, arachidonic acid metabolism was determined as a potentially important factor in the interaction between TB and DM pathophysiology. In a correlation network of the significantly altered molecules, among the central nodes, chenodeoxycholic acid was robustly associated with TB and DM. Fatty acid (22:4) was a component of all significant modules. In conclusion, the integration of multimodal metabolomics and lipidomics provides a thorough picture of the metabolic changes associated with TB-DM. The results obtained from this comprehensive profiling of TB patients with DM advance the current understanding of DM comorbidity in TB infection and contribute to the development of more effective treatment.

Para-aminosalicylic acid significantly reduced tenofovir exposure in human subjects: Mismatched findings from in vitro to in vivo translational research.

AIMS: Tenofovir and para-aminosalicylic acid (PAS) may be coprescribed to treat patients with concomitant infections of human immunodeficiency virus and Mycobacterium tuberculosis bacteria. Both drugs are known to have remarkable renal uptake transporter-mediated clearance. Owing to the lack of clinical studies on drug-drug interaction between the 2 drugs, we conducted a translational clinical study to investigate the effect of PAS on tenofovir pharmacokinetics (PK). METHODS: Initially, we studied in vitro renal uptake transporter-mediated drug-drug interactions using stably transfected cells with human organic anion transporters (OAT1 and OAT3). Later, we estimated clinical drug interactions using static and physiologically based PK modelling. Finally, we investigated the effects of PAS-calcium formulation (PAS-Ca) on tenofovir disoproxil fumarate PK in healthy male Korean subjects. RESULTS: PAS inhibited OAT1- and OAT3-mediated tenofovir uptake in vitro. The physiologically based PK drug-drug interaction model suggested a 1.26-fold increase in tenofovir peak plasma concentration when coadministered with PAS. By contrast, an open-label, randomized, crossover clinical trial evaluating the effects of PAS-Ca on tenofovir PK showed significantly altered geometric mean ratio (90% confidence intervals) of maximum plasma concentration (Cmax ) and area under the curve (AUC0-inf ) by 0.33 (0.28-0.38) and 0.29 (0.26-0.33), respectively. CONCLUSION: Our study findings suggest that the PAS-Ca formulation significantly reduced systemic exposure to tenofovir through an unexplained mechanism, which was contrary to the initial prediction. Caution should be exercised while predicting in vivo PK profiles from in vitro data, particularly when there are potential confounders such as pharmaceutical interactions.

Associations between HLA-A, -B, and -C alleles and iodinated contrast media-induced hypersensitivity in Koreans.

A common cause of drug hypersensitivity reactions is iodinated contrast media (ICM). ICM-induced hypersensitivity had been considered to be a non-immunological reaction, but evidence for an immunological mechanism has increased recently. Thus, we evaluated whether HLA-A, -B, and -C alleles were associated with ICM-induced hypersensitivity. In total, 126 patients who underwent contrast-enhanced computed tomography studies through outpatient clinics at a tertiary referral hospital between 2008 and 2012 were assessed. Sixty-one patients experienced ICM-induced hypersensitivity and the remainder, 65, were ICM-tolerant patients (control). ICM-induced hypersensitivity patients showed 51 with immediate, 7 with non-immediate, 3 with both or mixed type. HLA-A, -B, and -C genotyping was performed using a PCR sequence-based typing method. Four kinds of ICM were used: iopromide, iohexol, iobitridol, and iodixanol. The most used ICM among the hypersensitivity patients was iopromide. Significant difference in the frequency of HLA-B*58:01 (odds ratios [OR], 3.90; p = 0.0200, 95% confidence interval [CI], 1.16-13.07) was observed between ICM-induced immediate hypersensitivity and control. There were statistically significant differences in the frequencies of the HLA-B*38:02 (OR, 10.24; p = 0.0145; 95% CI, 1.09-96.14) and HLA-B*58:01 (OR, 3.98; p = 0.0348; 95% CI, 1.03-15.39) between iopromide-induced immediate hypersensitivity and control. The mechanism of ICM-induced hypersensitivity remains unknown, but this study showed associations, although weak, with HLA-B*58:01 alleles for ICM-induced immediate hypersensitivity and HLA-B*38:02 and HLA-B*58:01 for iopromide-induced immediate hypersensitivity as risk predictors. Further studies are needed to validate the associations in larger samples and to identify the functional mechanism behind these results.

A physiologically based pharmacokinetic/pharmacodynamic modeling approach for drug-drug interaction evaluation of warfarin enantiomers with sorafenib.

Sorafenib was suggested to cause drug-drug interaction (DDI) with the common anticoagulant, warfarin based on published studies. The inhibition on CYP2C9 enzyme was thought to be the mechanism, but further studies are warranted. Thus, a mechanistic PBPK/PD model for warfarin enantiomers was developed to predict DDI potential with sorafenib, aiming at providing reference for the rational use of both drugs. PBPK models of warfarin enantiomers were constructed by Simcyp software. A mechanistic PK/PD model was built in NONMEM software. PBPK model of sorafenib was fitted via a top-down method. The final PBPK/PD model of warfarin enantiomers was verified and validated by different dosing regimens, ethnicities and genetic polymorphisms, and used to perform DDI simulations between warfarin racemate and sorafenib among general populations and sub-populations with various CYP2C9 and VKORC1 genotypes. Results suggested low DDI risk between warfarin and sorafenib for general populations. Potentially serious consequence was seen for those carrying both CYP2C9 ∗2 and ∗3 and VKORC1 A/A genotypes. This PBPK/PD modeling approach for warfarin enantiomers enabled DDI evaluation with sorafenib. Close monitoring and warfarin dosage adjustment were recommended for patients carrying mutant genotypes. The novel model could be applied to investigate other drugs that may interact with warfarin.

Isoniazid Population Pharmacokinetics and Dose Recommendation for Korean Patients With Tuberculosis Based on Target Attainment Analysis.

The wide variability of isoniazid (INH) pharmacokinetics is mainly attributed to the trimodal N-acetyltransferase 2 (NAT2) acetylator phenotype, that is, rapid, intermediate, and slow. Consequently, a uniform INH dose in current clinical practice may lead to treatment failure and emergence of drug resistance. There is a lack of studies on specific doses of INH for different NAT2 acetylator phenotypes among tuberculosis (TB) patients. Therefore, we aimed to provide insight into the optimal dosing of INH for each NAT2 acetylator phenotype with respect to the probability of achieving a pharmacokinetic (PK)/pharmacodynamic target. PK, the NAT2 genotype, and clinical data were collected in a multicenter prospective cohort study conducted at 13 clinical centers in Korea. Population PK modeling and simulation were carried out. Data from 454 TB patients were divided into a training data set and a test data set at a ratio of 4 to 1. The PK of the training data were best described by a 2-compartment model with allometric scaling for body size effect. Importantly, NAT2 acetylator phenotypes significantly affected the apparent clearance. Our model, which provided better predictive performance compared with previously published models, was evaluated by external validation using the test set. The simulation for assessing target efficacy and toxicity indicated that the best INH dosing regimens for Korean tuberculosis patients were once-daily doses of 400, 300, and 200 mg for rapid, intermediate, and slow acetylators, respectively. In conclusion, our study provides a step forward in precision dosing for antituberculosis management.

Pharmacokinetic equivalence of CT-P17 to high-concentration (100 mg/ml) reference adalimumab: A randomized phase I study in healthy subjects.

This study aimed to demonstrate pharmacokinetic (PK) equivalence of a single dose of the proposed adalimumab biosimilar CT-P17 to United States-licensed adalimumab (US-adalimumab) and European Union-approved adalimumab (EU-adalimumab). This double-blind, parallel-group, phase I trial (clinicaltrials.gov NCT03970824) was conducted at 10 hospitals (Republic of Korea), in which healthy subjects (1:1:1) were randomized to receive a single 40 mg (100 mg/ml) subcutaneous injection of CT-P17, US-adalimumab, or EU-adalimumab. Primary end points were PK equivalence in terms of: area under the concentration-time curve from time zero to infinity (AUC0-inf ); AUC from time zero to the last quantifiable concentration (AUC0-last ); and maximum serum concentration (Cmax ). PK equivalence was concluded if 90% confidence intervals (CIs) for percent ratios of geometric least squares means (GLSMs) for pairwise comparisons were within the equivalence margin of 80-125%. Additional PK end points, safety, and immunogenicity were evaluated. Of the 312 subjects who were randomized (103 CT-P17; 103 US-adalimumab; 106 EU-adalimumab), 308 subjects received study drug. AUC0-inf , AUC0-last , and Cmax were equivalent among CT-P17, US-adalimumab, and EU-adalimumab, because 90% CIs for the ratios of GLSMs were within the 80-125% equivalence margin for each pairwise comparison. Secondary PK end points, safety, and immunogenicity were similar between treatment groups. In conclusion, PK equivalence for single-dose administration of CT-P17, EU-adalimumab, and US-adalimumab was demonstrated in healthy adults. Safety and immunogenicity profiles were comparable between treatment groups and consistent with previous reports for adalimumab biosimilars.

Pharmacokinetics and Pharmacodynamics of Tegoprazan Coadministered With Amoxicillin and Clarithromycin in Healthy Subjects.

This clinical trial was conducted to evaluate the pharmacokinetics and pharmacodynamics of tegoprazan when coadministered with amoxicillin/clarithromycin in healthy subjects. Cohort 1 was an open-label, randomized multiple-dose study to evaluate the mutual interaction of tegoprazan and amoxicillin/clarithromycin on the disposition of 3 tested drugs including tegoprazan M1 metabolite and 14-hydroxyclarithromycin (14-OH-clarithromycin). Cohort 2 was an open-label, randomized, active-controlled, parallel multiple-dose study to compare the intragastric pH profile after multiple oral doses of 50 or 100 mg tegoprazan coadministered with amoxicillin/clarithromycin 1000/500 mg for 7 days and pantoprazole-based triple therapy as the comparator arm. The coadministration of tegoprazan with amoxicillin/clarithromycin increased Css,max (2.2-fold) and AUCτ (2.7-fold) of tegoprazan and M1 (2.1- and 2.2-fold for Css,max and AUCτ , respectively) compared with administration of tegoprazan alone. The Css,max and AUCτ of 14-OH-clarithromycin increased by 1.7- and 1.8-fold, respectively; the disposition of amoxicillin and clarithromycin were not significantly changed. On days 1 and 7 of treatment, tegoprazan-based therapies (both 50- and 100-mg therapies) maintained pH above 6 for more than 88% of the 24-hour period, which was significantly longer compared with pantoprazole-based therapy. Tegoprazan either alone or in combination with amoxicillin/clarithromycin was well tolerated in healthy subjects. In conclusion, the exposure of tegoprazan was increased after coadministration of amoxicillin/clarithromycin, which led to increase pharmacodynamic response measured by intragastric pH compared with tegoprazan alone. Therefore, tegoprazan-based triple therapy would be effective therapeutic regimen to manage intragastric pH in terms of gastric or duodenal ulcers healing, treatment of gastroesophageal reflux disease, and Helicobacter pylori eradication.

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.

Pharmacokinetic modeling analysis of cilostazol and its active metabolites (OPC-13015 and OPC-13213) after multiple oral doses of cilostazol in healthy Korean volunteers.

Cilostazol is a selective inhibitor of phosphodiesterase III (PDE III), which is prescribed for patients with peripheral arterial disease, especially intermittent claudication. The purpose of the study was to investigate the pharmacokinetic (PK) of cilostazol and its metabolites on the immediate (IR) formulation of cilostazol in healthy Korean male volunteers by population PK modeling analysis implemented using NONMEM software.A 2 × 2 crossover study comparing multiple oral doses of IR and SR formulations of cilostazol were conducted. Serial plasma concentrations of cilostazol and its active metabolites were used in this analysis.The PK was best depicted by one-compartment model, with absorption kinetics of cilostazol having mixed first- and zero-order kinetics with a time delay at the beginning of absorption. The introduction of interoccasion variabilities into zero-order (D1), first-order (Ka), and relative bioavailability (F1) significantly improved the model fit, and total body water (TBW) was identified as a significant covariate positively affecting the clearance of cilostazol. The model validation suggested that the model constructed in this study predicted the plasma concentration of cilostazol and its two active metabolites reasonably well.The PK model we developed explored the PK characteristics of cilostazol in Korean male subjects, and may be useful for identifying optimal individual dosing regimens of cilostazol.

Pharmacokinetics of fixed-dose combination of atorvastatin and metformin compared with individual tablets.

Purpose: The aims of this study was to investigate the mutual pharmacokinetic interactions between steady-state atorvastatin and metformin and the effect of food on the fixed-dose combined (FDC) tablet of atorvastatin and metformin extended release (XR). Subjects and methods: Study 1, an open-labeled, fixed sequence, multiple-dose pharmacokinetic drug-drug interaction study, was divided into 2 parts. Atorvastatin (40 mg) or metformin (1,000 mg) XR tablets were administered once daily via mono- or co-therapy for 7 days. Plasma levels of atorvastatin and 2-OH-atorvastatin, were quantitatively determined for 36 h in part A (n=50) while metformin plasma concentration was measured up to 24 h in part B (n=16) after the last dosing. Study 2, a randomized, open-labeled, single-dose, two-treatment, two-period, two-sequence crossover study, involved 27 healthy subjects to investigate the impact of food intake on the pharmacokinetics of a combined atorvastatin/metformin XR 20/500 mg (CJ-30056 20/500 mg) tablet. Results: After multiple doses of mono- or co-therapy of atorvastatin (40 mg) and metformin (1,000 mg) XR, the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) for the peak plasma concentration at steady state (Cmax,ss) and area under the plasma concentration-time curve during the dosing interval at steady state (AUCτ,ss) were 1.07 (0.94-1.22) and 1.05 (0.99-1.10) for atorvastatin, 1.06 (0.96-1.16) and 1.16 (1.10-1.21) for 2-OH-atorvastatin, and 1.00 (0.86-1.18) and 0.99 (0.87-1.13) for metformin, respectively. Food delayed time to reach maximum concentration (tmax), decreased atorvastatin Cmax by 32% with a GMR (90% CI) of 0.68 (0.59-0.78), and increased metformin AUCt by 56% with a GMR (90% CI) of 1.56 (1.43-1.69). Conclusion: No clinically relevant pharmacokinetic interaction was seen when atorvastatin was co-administered with metformin. Food appeared to change the absorption of atorvastatin and metformin from an FDC formulation. These alterations were in accordance with those described with the single reference drugs when ingested with food.

Pharmacokinetic comparison of a fixed-dose combination versus concomitant administration of amlodipine, olmesartan, and rosuvastatin in healthy adult subjects.

Objective: The aim of this study was to compare the pharmacokinetic (PK) and safety profiles of a fixed dose combination (FDC) formulation and co-administration of amlodipine, olmesartan, and rosuvastatin. Materials and methods: This study was an open-label, randomized, cross-over design conducted in healthy male volunteers. All subjects received either a single FDC tablet containing amlodipine 10 mg/olmesartan 40 mg/rosuvastatin 20 mg, or were co-administered an FDC tablet containing amlodipine 10 mg/olmesartan 40 mg and a tablet containing rosuvastatin 20 mg, for each period, with 14-day washout periods. Plasma concentrations of amlodipine, olmesartan, and rosuvastatin were measured by liquid chromatography tandem mass spectrometry. Safety was evaluated by measuring vital signs, clinical laboratory parameters, physical examinations, and medical interviews. Results: Sixty-four subjects were enrolled, and 54 completed the study. The geometric mean ratios and 90% CI for the maximum plasma concentration (Cmax) and area under the curve from time zero to the last sampling time (AUCt) were 1.0716 (1.0369,1.1074) and 1.0497 (1.0243,1.0757) for amlodipine, 1.0396 (0.9818,1.1009) and 1.0138 (0.9716,1.0578) for olmesartan, and 1.0257 (0.9433,1.1152) and 1.0043 (0.9453,1.0669) for rosuvastatin. Fourteen cases of adverse events occurred in 12 subjects. There was no statistically significant clinical difference between the formulation groups. Conclusion: The 90% CI of the primary PK parameters were within the acceptance bioequivalence criteria, which is ln (0.8) and ln (1.25). These results indicate that the FDC formulation and co-administration of amlodipine, olmesartan and rosuvastatin are pharmacokinetically bioequivalent and have similar safety profiles.

A Randomized, Double-Blind Trial Comparing the Pharmacokinetics of CT-P16, a Candidate Bevacizumab Biosimilar, with its Reference Product in Healthy Adult Males.

BACKGROUND: CT-P16 is a candidate biosimilar of bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor that is used in the treatment of a range of advanced solid cancers. OBJECTIVE: The objective of this study was to demonstrate the pharmacokinetic equivalence of CT-P16 and European Union (EU)-approved bevacizumab (EU-bevacizumab) and US-licensed bevacizumab (US-bevacizumab) reference products. METHODS: In this double-blind, parallel-group phase I trial (ClinicalTrials.gov identifier NCT03247673), healthy adult males were randomized (1:1:1) to receive a single dose of CT-P16 5 mg/kg, EU-bevacizumab 5 mg/kg, or US-bevacizumab 5 mg/kg. Primary study endpoints were area under the concentration-time curve (AUC) from time zero to infinity (AUC∞), AUC from time zero to the last quantifiable concentration (AUClast), and maximum serum concentration (Cmax). Pharmacokinetic equivalence was shown if the 90% confidence intervals (CIs) of the geometric mean (GM) ratios of the AUC∞, AUClast, and Cmax were within the predefined bioequivalence margin of 80-125%. Safety and immunogenicity were also evaluated. RESULTS: A total of 144 subjects were randomized: 47 to CT-P16, 49 to EU-bevacizumab, and 48 to US-bevacizumab. The 90% CIs for the GM ratios of AUC∞, AUClast, and Cmax for CT-P16/EU-bevacizumab, CT-P16/US-bevacizumab, and EU-bevacizumab/US-bevacizumab comparisons were all within the bioequivalence margin. Mean serum concentration-time profiles, secondary pharmacokinetic parameters, and safety and immunogenicity profiles were comparable across all three treatment groups. CONCLUSION: CT-P16 demonstrated pharmacokinetic equivalence to EU-bevacizumab and US-bevacizumab. Safety and immunogenicity profiles were similar for CT-P16, EU-bevacizumab, and US-bevacizumab. These data support the further clinical evaluation of CT-P16 as a bevacizumab biosimilar. CLINICAL TRIALS REGISTRATION: NCT03247673.

Effect of Cilostazol on the Pharmacokinetics of Simvastatin in Healthy Subjects.

PURPOSE: We evaluated potential drug-drug interactions between cilostazol and simvastatin, both CYP3A substrates, in healthy subjects. METHODS: An open-label, two-period, fixed-sequence clinical study was conducted. Seventeen subjects were given a single oral dose of simvastatin 40 mg on day 1 and multiple oral doses of cilostazol 100 mg twice daily on days 2 to 5 followed by a single dose of cilostazol and simvastatin on day 6. Plasma concentrations of simvastatin and its active metabolite, simvastatin acid, were measured using liquid chromatography-tandem mass spectrometry for pharmacokinetic assessment. Moreover, serum lipid profiles under fasting conditions were determined. RESULTS: The geometric mean ratios of the area under the plasma concentration-time curve from time zero to time infinity of simvastatin combined with cilostazol to that of simvastatin alone were 1.64 (90% CI, 1.38-1.95) for simvastatin and 1.31 (1.04-1.66) for simvastatin acid. In addition, coadministration with cilostazol significantly increased the maximum concentration of simvastatin and simvastatin acid, up to 1.8-fold and 1.6-fold, respectively. However, the effects of a single dose of simvastatin on serum lipid profiles were not affected notably when simvastatin was coadministered with cilostazol. CONCLUSIONS: Multiple doses of cilostazol increased the systemic exposure of simvastatin and simvastatin acid following a single dose of simvastatin.

Physiologically Based Pharmacokinetic Modeling Approach to Predict Drug-Drug Interactions With Ethionamide Involving Impact of Genetic Polymorphism on FMO3.

The widely used second-line antituberculosis drug ethionamide shows wide interindividual variability in its disposition; however, the relevant factors affecting this phenomenon have not been characterized. We previously reported the major contribution of flavin-containing monooxygenase 3 (FMO3) in the reductive elimination pathway of ethionamide. In this study, ethionamide metabolism was potentially inhibited by methimazole in vitro. The drug-drug interaction leading to methimazole affecting the disposition of ethionamide mediated by FMO3 was then quantitated using a bottom-up approach with a physiologically based pharmacokinetic framework. The maximum concentration (Cmax ) and area under the curve (AUC) of ethionamide were estimated to increase by 13% and 16%, respectively, when coadministered with methimazole. Subsequently, we explored the effect of FMO3 genetic polymorphism on metabolic capacity, by constructing 2 common functional variants, Lys158 -FMO3 and Gly308 -FMO3. Compared to the wild type, recombinant Lys158 -FMO3 and Gly308 -FMO3 variants significantly decreased the intrinsic clearance of ethionamide by 2% and 24%, respectively. Two prevalent functional variants of FMO3 were predicted to affect ethionamide disposition, with mean ratios of Cmax and AUC of up to 1.5 and 1.7, respectively, in comparison with the wild type. In comparing single ethionamide administration with the wild type, simulations of the combined effects of comedications and FMO3 genetic polymorphism estimated that the Cmax and AUC ratios of ethionamide increased up to 1.7 and 2.0, respectively. These findings suggested that FMO3-mediated drug-drug interaction and genetic polymorphism could be important determinants of interindividual heterogeneity in ethionamide disposition that need to be considered comprehensively to optimize the personalized dosing of ethionamide.

Antiepileptic drug-induced severe cutaneous adverse reactions and HLA alleles: A report of five cases with lymphocyte activation test.

Antiepileptic drugs (AEDs) can induce severe cutaneous adverse reactions (SCARs) such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. We performed HLA genotyping and lymphocyte activation tests (LATs) for five AED-induced SCAR patients (three males and two females; aged 40-66 years old). Three patients were treated with carbamazepine (CBZ) for pain control, one was treated with phenytoin (PHT) for seizure prevention, and one was treated with valproic acid (VPA) for seizure prevention. One patient was diagnosed with CBZ-induced DRESS syndrome and the remaining patients were diagnosed with SJS. All patients recovered from SCARs after stopping suspicious drugs and supportive care. LATs were conducted to confirm the culprit drug responsible for inducing SCARs; and LAT results were positive for the suspected culprit drugs, in all except in one case. HLA-A, -B, and -C alleles were determined using PCR-sequence-based typing method. The common alleles of HLA were -A*02:01, -B*51:01, and -C*03:04 which were carried by three patients (60%) for each allele. The patient with CBZ-induced DRESS syndrome carried the HLA-A* 31:01 allele. One patient with CBZ-induced SJS and one patient with VPA-induced SJS carried the HLA-B*15:11 allele. No patients carried the HLA-B*15:02 allele, which is a known risk allele of AED-induced SCARs. Further investigation of the three common alleles found in the five AED-induced SCARs patients is needed. We demonstrated the usefulness of LAT for confirming the culprit drug.

Development of a Physiologically Based Pharmacokinetic Model of Ethionamide in the Pediatric Population by Integrating Flavin-Containing Monooxygenase 3 Maturational Changes Over Time.

Currently, ethionamide is the most frequently prescribed second-line antituberculosis drug in children. After extensive metabolism by flavin-containing monooxygenase (FMO) isoform 3 in the liver, the drug may exert cytotoxic effects. The comparison of children in different age groups revealed a significant age-related increase in ethionamide elimination in vivo. However, to date, the exact mechanism underlying this dynamic increase in ethionamide elimination has not been elucidated. We hypothesized that the age-dependent changes in ethionamide elimination were predominantly a result of the progressive increases in the expression and metabolic capacity of FMO3 during childhood. To test this hypothesis, a full physiologically based pharmacokinetic (PBPK) model of ethionamide was established and validated in adults through incorporation of comprehensive metabolism and transporter profiles, then expanded to the pediatric population through integration of FMO3 maturational changes over time. Thus, a good prediction PBPK model was validated successfully both in adults and children and applied to demonstrate the critical contribution of FMO3 in the mechanistic elimination pathway of ethionamide. In addition, a significant correlation between clearance and age was observed in children by accounting for ethionamide maturation, which could offer a mechanistic understanding of the age-associated changes in ethionamide elimination. In conclusion, this study underlines the benefits of in vitro-in vivo extrapolation and a quantitative PBPK approach for the investigation of transporter-enzyme interplay in ethionamide disposition and the demonstration of FMO3 ontogeny in children.

Pharmacokinetic comparison of a fixed-dose combination versus concomitant administration of fimasartan, amlodipine, and rosuvastatin using partial replicated design in healthy adult subjects.

OBJECTIVE: The aim of this study was to compare the pharmacokinetics (PK) and safety profiles of a fixed-dose combination (FDC) formulation of fimasartan, amlodipine, and rosuvastatin with the co-administration of the two products by using a replicated crossover study design in healthy male subjects. RESULTS: This was an open-label, randomized, three-sequence, three-period replicated crossover study in healthy male subjects. The replicated crossover design was done because of high coefficient of variation of PK parameter for fimasartan, that is, >30%. With a 14 days washout period, an FDC tablet containing 60 mg fimasartan, 10 mg amlodipine, and 20 mg rosuvastatin was administered only once, and separate formulations of fimasartan/amlodipine 60 mg/10 mg FDC tablet and 20 mg rosuvastatin tablet administered twice. Blood samples were collected up to 72 hours following drug administration. The plasma concentrations of fimasartan, amlodipine, and rosuvastatin were measured by liquid chromatography tandem mass spectrometry. Safety was assessed by evaluating vital signs, clinical laboratory parameters, physical examinations, and medical interviews. RESULTS: The geometric mean ratios and 90% confidence intervals (CIs) for the maximum plasma concentration (Cmax) and area under the curve from time zero to the last measurable sampling time (AUCt) were 1.0776 (0.9201-1.2622) and 0.9978 (0.9538-1.0439) for fimasartan, 1.0038 (0.9782-1.0301) and 1.0055 (0.9828-1.0288) for amlodipine, and 1.0006 (0.9290-1.0776) and 0.9986 (0.9532-1.0461) for rosuvastatin, respectively. A total of 22 adverse events (AEs) were reported by 60 subjects; there were no significant differences in the incidence of AEs between the two groups. CONCLUSION: The 90% CI of the Cmax of fimasartan was within the widened acceptance limit, ln(0.6984)-ln(1.4319). The 90% CIs of the other PK parameters for drugs were between ln(0.8) and ln(1.25). These results suggest that the FDC formulation is pharmacokinetically bioequivalent and has a similar safety profile, to the co-administration of its three constituent drugs.