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For topically applied over-the-counter (OTC) products, the association of unwanted systemic exposure and adverse events may be difficult to ascertain without a recognition or determination of in vivo absorption. Evaluation of skin permeability using a validated in vitro permeation methodology can provide important information for both initial formulation selection and reformulation during the product life cycle. Additionally, a comparison of permeation rates between formulations using a validated methodology could reduce the number of nonclinical studies needed as part of reformulation. However, many in vitro permeation tests (IVPTs) have produced results with high variability and low reproducibility between study sites. It is unclear if this is due to a lack of a standardized protocol, or lack of control of multiple key experimental factors including skin source, preparation, receptor fluid, and study design. This review presents the authors perspective on the potential regulatory utility of IVPT and proposes steps to improve the accuracy and reproducibility of IVPT. The focus of this review is on topical dermatologic drugs with an initial emphasis on the OTC marketplace where reformulations are more common.

Importance In 2019, the US Food and Drug Administration (FDA) received a citizen petition indicating that ranitidine contained the probable human carcinogenN-nitrosodimethylamine (NDMA). In addition, the petitioner proposed that ranitidine could convert to NDMA in humans; however, this was primarily based on a small clinical study that detected an increase in urinary excretion of NDMA after oral ranitidine consumption. Objective To evaluate the 24-hour urinary excretion of NDMA after oral administration of ranitidine compared with placebo. Design, Setting, and Participants Randomized, double-blind, placebo-controlled, crossover clinical trial at a clinical pharmacology unit (West Bend, Wisconsin) conducted in 18 healthy participants. The study began in June 2020, and the end of participant follow-up was July 1, 2020. Interventions Participants were randomized to 1 of 4 treatment sequences and over 4 periods received ranitidine (300 mg) and placebo (randomized order) with a noncured-meats diet and then a cured-meats diet. The cured-meats diet was designed to have higher nitrites, nitrates (nitrate-reducing bacteria can convert nitrates to nitrites), and NDMA. Main Outcome and Measure Twenty-four–hour urinary excretion of NDMA. Results Among 18 randomized participants (median age, 33.0 [interquartile range {IQR}, 28.3 to 42.8] years; 9 women [50%]; 7 White [39%], 11 African American [61%]; and 3 Hispanic or Latino ethnicity [17%]), 17 (94%) completed the trial. The median 24-hour NDMA urinary excretion values for ranitidine and placebo were 0.6 ng (IQR, 0 to 29.7) and 10.5 ng (IQR, 0 to 17.8), respectively, with a noncured-meats diet and 11.9 ng (IQR, 5.6 to 48.6) and 23.4 ng (IQR, 8.6 to 36.7), respectively, with a cured-meats diet. There was no statistically significant difference between ranitidine and placebo in 24-hour urinary excretion of NDMA with a noncured-meats diet (median of the paired differences, 0 [IQR, −6.9 to 0] ng;P = .54) or a cured-meats diet (median of the paired differences, −1.1 [IQR, −9.1 to 11.5] ng;P = .71). No drug-related serious adverse events were reported. Conclusions and Relevance In this trial that included 18 healthy participants, oral ranitidine (300 mg), compared with placebo, did not significantly increase 24-hour urinary excretion of NDMA when participants consumed noncured-meats or cured-meats diets. The findings do not support that ranitidine is converted to NDMA in a general, healthy population. Trial Registration ClinicalTrials.gov Identifier:NCT04397445

In this report, we present a case study of how pharmacogenomics and pharmacometabolomics can be useful to characterize safety and pharmacokinetic profiles in early phase new drug development clinical trials. During conducting a first-in-human trial for a new molecular entity, we were able to determine the mechanism of dichotomized variability in plasma drug concentrations, which appeared closely related to adverse drug reactions (ADRs) through integrated omics analysis. The pharmacogenomics screening was performed from whole blood samples using the Affymetrix DMET (Drug-Metabolizing Enzymes and Transporters) Plus microarray, and confirmation of genetic variants was performed using real-time polymerase chain reaction. Metabolomics profiling was performed from plasma samples using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. A GSTM1 null polymorphism was identified in pharmacogenomics test and the drug concentrations was higher in GSTM1 null subjects than GSTM1 functional subjects. The apparent drug clearance was 13-fold lower in GSTM1 null subjects than GSTM1 functional subjects (p < 0.001). By metabolomics analysis, we identified that the study drug was metabolized by cysteinylglycine conjugation in GSTM functional subjects but those not in GSTM1 null subjects. The incidence rate and the severity of ADRs were higher in the GSTM1 null subjects than the GSTM1 functional subjects. Through the integrated omics analysis, we could understand the mechanism of inter-individual variability in drug exposure and in adverse response. In conclusion, integrated multi-omics analysis can be useful for elucidating the various characteristics of new drug candidates in early phase clinical trials.

SummaryBackground YH4808, a K+-competitive acid blocker, is under clinical development for the treatment of acid-related disorders, such as gastroesophageal reflux disease. Aims We aimed to determine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of YH4808, compared to placebo and esomeprazole. Methods This double-blind, randomised, placebo- and active comparator (esomeprazole)-controlled study was conducted with 123 healthy male volunteers. We evaluated YH4808 (30-800 mg) properties, administered in single (N=55) and multiple (N=24) oral doses, and recorded the effects on 24-hour intragastric acidity. Results were compared to placebo (N=20) and esomeprazole 40 mg (N=24). Results Plasma YH4808 exposure increased dose-proportionally and declined in a multi-phasic manner. YH4808 ≥200 mg/d maintained intragastric acidity at pH >4 for longer times than esomeprazole during both day and night (%Time at pH >4: >70% vs 58% of a 24-hour period, respectively; and >50% vs 33% of a 9-hour night respectively). A twice-daily regimen of YH4808 more effectively controlled intragastric pH at night than a once-daily regimen. In evaluating the mean areas under the intragastric pH-time curves in 15-minute intervals for 2 hours after dosing, we found that YH4808 had a faster onset than esomeprazole. Moreover, unlike esomeprazole, YH4808 PK and PD were not significantly affected by the CYP2C19 genotype of the subjects. YH4808 was well-tolerated at all doses administered. Conclusion This study showed that YH4808 produced a rapid, sustained suppression of gastric secretion with good tolerability. The results at YH4808 ≥200 mg/d provide a rationale for further clinical investigations in populations with acid-related diseases.

Dongseong Shin,1 SeungHwan Lee,2 Sojeong Yi,2 Seo Hyun Yoon,2 Joo-Youn Cho,2 Mi Young Bahng,3 In-Jin Jang,2 Kyung-Sang Yu2 1Clinical Trials Center, Gachon University Gil Medical Center, Incheon, 2Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, 3Department of Product Development, Dong-A ST, Seoul, Korea Objective: DA-8031 is a selective serotonin reuptake inhibitor under development for the treatment of premature ejaculation. This is the first-in-human study aimed at evaluating the pharmacokinetics and tolerability of DA-8031 and its metabolites (M1, M2, M4, and M5) in the plasma and urine after administration of a single oral dose in healthy male subjects.Methods: A dose block-randomized, double-blind, placebo-controlled, single ascending dose study was conducted. Subjects received either placebo or a single dose of DA-8031 at 5, 10, 20, 40, 60, 80, or 120 mg. DA-8031 and its four metabolites were analyzed in the plasma and urine for pharmacokinetic evaluation. The effect of genetic polymorphisms of cytochrome-P450 (CYP) enzymes on the pharmacokinetics of DA-8031 was evaluated.Results: After a single dose, plasma DA-8031 reached the maximum concentration at a median of 2–3 h and was eliminated with terminal elimination half-life of 17.9–28.7 h. The mean renal clearance was 3.7–5.6 L/h. Dose-proportional pharmacokinetics was observed over the dose range of 20–80 mg. Among the metabolites, M4 had the greatest plasma concentration, followed by M5 and M1. Subjects with CYP2D6 intermediate metabolizer had significantly greater dose-normalized Cmax and AUC0–t of DA-8031 as well as smaller metabolic ratios than those subjects with CYP2D6 extensive metabolizer. The most common adverse events were nausea, dizziness, and headache, and no serious adverse events were reported.Conclusion: In conclusion, the systemic exposure of DA-8031 was increased proportionally to the dose within 20–80 mg. Genetic polymorphisms of CYP2D6 had an effect on the systemic exposure of DA-8031. DA-8031 was well tolerated after single doses of 80 mg or less. Keywords: DA-8031, pharmacokinetics, selective serotonin reuptake inhibitor, premature ejaculation, first-in-human

Dexmedetomidine is a selective alpha-2 adrenergic agonist with concurrent sedative and analgesic effects, and it is being increasingly used in pediatric anesthesia and intensive care. This study aimed to investigate the pharmacokinetics of intravenous dexmedetomidine in mechanically ventilated children in the intensive care unit (ICU) after neurosurgery. Pediatric patients aged 2&ndash, 12 years, who were mechanically ventilated in ICU after neurosurgery, were allocated into a low-dose (n = 15) or high-dose (n = 14) group. The low-dose group received dexmedetomidine at a loading dose of 0.25 &micro, g/kg for 10 min, followed by a maintenance dose of 0.25 &micro, g/kg/h for 50 min, whereas the high-dose group received dexmedetomidine at a loading dose of 0.5 &micro, g/kg for 10 min, followed by a maintenance dose of 0.5 &micro, g/kg/h for 50 min. Serial blood samples were collected for a pharmacokinetic analysis up to 480 min after the end of the infusion. The sedative effect of dexmedetomidine was assessed using the Bispectral Index and University of Michigan Sedation Scale. Adverse reactions, electrocardiography findings, and vital signs were monitored for a safety assessment. A population pharmacokinetic analysis was performed using non-linear mixed effects modeling. Dexmedetomidine induced a moderate-to-deep degree of sedation during infusion in both groups. The pharmacokinetics of dexmedetomidine were best described by a two-compartment disposition model with first-order elimination kinetics. The parameters were standardized for a body weight of 70 kg using an allometric power model. The population estimates (95% confidence interval) per 70 kg body weight were as follows: clearance of 81.0 (72.9&ndash, 90.9) L/h, central volume of distribution of 64.2 (50.6&ndash, 81.0) L, intercompartment clearance of 116.4 (90.6&ndash, 156.0) L/h, and peripheral volume of distribution of 167 (132&ndash, 217) L. No serious adverse reactions or hemodynamic changes requiring the discontinuation of dexmedetomidine were observed. Dexmedetomidine had increased clearance and volume of distribution in mechanically ventilated children in ICU after neurosurgery, thereby indicating the need to adjust the dosage to obtain a target plasma concentration.

Phenotypic differences in drug responses have been associated with known pharmacogenomic loci, but many remain to be characterized. Therefore, we developed next-generation sequencing (NGS) panels to enable broad and unbiased inspection of genes that are involved in pharmacokinetics (PKs) and pharmacodynamics (PDs). These panels feature repetitively optimized probes to capture up to 114 PK/PD-related genes with high coverage (99.6%) and accuracy (99.9%). Sequencing of a Korean cohort (n = 376) with the panels enabled profiling of actionable variants as well as rare variants of unknown functional consequences. Notably, variants that occurred at low frequency were enriched with likely protein-damaging variants and previously unreported variants. Furthermore, in vitro evaluation of four pharmacogenes, including cytochrome P450 2C19 (CYP2C19), confirmed that many of these rare variants have considerable functional impact. The present study suggests that targeted NGS panels are readily applicable platforms to facilitate comprehensive profiling of pharmacogenes, including common but also rare variants that warrant screening for personalized medicine.

To explore potential biomarkers for amoxicillin/clavulanate-induced liver injury (AC-DILI), we conducted a clinical trial in 32 healthy subjects based on multi-omics approaches. Every subject was administered amoxicillin/clavulanate for 14 days. The liver-specific microRNA-122 (miR-122) level increased prior to and correlated well with the observed alanine aminotransferase (ALT) level increase. This result indicates its potential as a sensitive early marker for AC-DILI. We also identified urinary metabolites, such as azelaic acid and 7-methylxanthine, with levels that significantly differed among the groups classified by ALT elevation level on day 8 after drug administration (P < 0.05). Lymphocyte proliferation in response to the drug was also observed. These findings demonstrate sequential changes in the process of AC-DILI, including metabolic changes, increased miR-122 level, increased liver enzyme activity, and enhanced lymphocyte proliferation after drug administration. In conclusion, this study provides potential biomarkers for AC-DILI based on currently known mechanisms using comprehensive multi-omics approaches.

Physiologically based pharmacokinetic (PBPK) modelling and simulation is a useful tool in predicting the PK profiles of a drug, assessing the effects of covariates such as demographics, ethnicity, genetic polymorphisms and disease status on the PK, and evaluating the potential of drug-drug interactions. We developed a Korean-specific virtual population for the SimCYP® Simulator (version 15 used) and evaluated the population's predictive performance using six substrate drugs (midazolam, S-warfarin, metoprolol, omeprazole, lorazepam and rosuvastatin) of five major drug metabolizing enzymes (DMEs) and two transporters. Forty-three parameters including the proportion of phenotypes in DMEs and transporters were incorporated into the Korean-specific virtual population. The simulated concentration-time profiles in Koreans were overlapped with most of the observed concentrations for the selected substrate drugs with a < 2-fold difference in clearance. Furthermore, we found some drug models within the SimCYP® library can be improved, e.g., the minor allele frequency of ABCG2 and the fraction metabolized by UGT2B15 should be incorporated for rosuvastatin and lorazepam, respectively. The Korean-specific population can be used to evaluate the impact of ethnicity on the PKs of a drug, particularly in various stages of drug development.

Accurate prediction of cytochrome P450 (CYP) 3A activity in the early stage of drug development and in clinical practice is important. This study aimed to evaluate the previously constructed CYP3A activity prediction model after administration of CYP3A inhibitors and inducers and to modify the model for better prediction of CYP3A activity. Healthy male subjects received the following study drugs during three study periods: midazolam alone (control phase); midazolam with 200 mg of itraconazole (CYP3A inhibition phase); and midazolam with 150 mg of rifampicin (CYP3A induction phase). We quantified the concentrations of several endogenous CYP3A markers in both urine and plasma using gas chromatography-mass spectrometry. The urinary markers, including 6β-hydroxy (OH)-cortisol/cortisol, 6β-OH-cortisone/cortisone, 16α-OH-dehydroepiandrosterone (DHEA)/DHEA, 16α-OH-androstenedione (A-dione)/A-dione and 7β-OH-DHEA/DHEA, were significantly correlated with midazolam clearance in both the CYP3A inhibition and induction phases. We constructed a statistical prediction model after integrating data from a previous study to predict midazolam clearance as follows: Ln(midazolam clearance) = 2.5545 + 0.3988 × ln(7β-OH-DHEA/DHEA) + 0.1984 × ln(16α-OH-DHEA/DHEA) + 0.5031 × ln(6β-OH-cortisol/cortisol) – 0.1261 [ln(7β-OH-DHEA/DHEA) × ln(6β-OH-cortisol/cortisol)] (r2 = 0.75). We suggest that quantitating endogenous markers in vivo coupled with the statistical prediction model may be useful for predicting CYP3A parameters.

We hypothesized that the pharmacodynamic (PD) characteristics of metformin would change with inhibition of the multidrug and toxin extrusion (MATE) transporter, which mediates renal elimination of metformin. Twenty healthy male subjects received two doses (750/500 mg) of metformin, with and without 50 mg of pyrimethamine (a potent MATE inhibitor), with 1 week of washout in between each dose. The PD characteristics of metformin were assessed using oral glucose tolerance tests (OGTTs) before and after the metformin dose. Metformin concentrations in plasma and urine were determined using liquid chromatography-electrospray ionization-tandem mass spectrometry. When metformin was co-administered with pyrimethamine, its area under the concentration-time curve from 0 to 12 h was 2.58-fold greater (p

This study aimed to assess the pharmacokinetics of cyclosporine A (CsA) in Asian children with renal impairment (RI) by developing a physiologically-based pharmacokinetic (PBPK) model with Simcyp Simulator. The PBPK model of Asian children with RI was developed by modifying the physiological parameters of the built-in population libraries in Simcyp Simulator. The ratio of healthy and RI populations was obtained for each parameter showing a difference between the populations. Each ratio was multiplied by the corresponding parameter in healthy Asian children. The model verification was performed with published data of Korean children with kidney disease given multiple CsA administrations. Simulations were performed with different combinations of ethnicity, age, and renal function to identify the net impact of each factor. The simulated results suggested that the effect of RI was higher in children than adults for both Caucasian and Asian. In conclusion, the constructed model adequately characterized CsA pharmacokinetics in Korean children with RI. Simulations with populations categorized by ethnicity, age, and renal function enabled to assess the net impact of each factor on specific populations.

Three kinds of herbal medicines, commonly used in Korea, Angelicae tenuissima radix, Angelicae dahuricae radix and Scutellariae radix were studied to evaluate their effect on cytochrome P450 (CYP) activities in healthy volunteers. A total of 24 healthy male volunteers were assigned to one of three parallel herbal treatment groups, each consisting of eight volunteers. A cocktail of probe drugs for CYP enzymes was orally administered before and after multiple administrations of herbal medicines, three times a day for 13 days. Probe drugs used to measure CYP activities were caffeine (CYP1A2), losartan (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4). The probe drugs and their metabolites were quantified in plasma or urine using HPLC or LC-MS/MS. Changes in each CYP activity was evaluated by metabolic ratio of the probe drug (concentration ratio of metabolite to parent form at reference time point) following the herbal medication period, compared to the baseline values. A. dahuricae radix significantly decreased CYP1A2 activity to 10% of baseline activity (95% CI: 0.05-0.21). S. radix also showed significant changes in CYP2C9 and CYP2E1 activities. Compared to baseline values, the metabolic activities of losartan were decreased to 71% (0.54-0.94). In addition, S. radix showed a 1.42-fold (1.03-1.97) increase in chlorzoxazone metabolic activity. However, CYP activities were not meaningfully influenced by A. tenuissima radix. Changes in certain CYP activities were observed after the administration of S. radix and A. dahuricae radix in healthy volunteers. Therefore, herbal medicines containing S. radix or A. dahuricae radix are candidates for further evaluation of clinically significant CYP-mediated herb-drug interactions in human beings.

Background: Ticlopidine is an antiplatelet agent used for the prevention of vascular accidents. In clinical practice in Korea, ginkgo extract may be administered along with ticlopidine to enhance the inhibition of platelet aggregation. Objective: To meet the requirements for marketing a combined fixed-dose formulation in Korea, the investigators compared the pharmacokinetic characteristics of ticlopidine in a combined fixed-dose tablet of ticlopidine/ginkgo extract with the concomitant administration of ticlopidine and ginkgo extract tablets. Methods: An open-label, 2-period, 2-treatment, single-dose, randomized-sequence crossover study was conducted in healthy Korean male volunteers. Subjects were randomly allocated to 2 sequence groups. In one period, a combined ticlopidine 250 mg/ ginkgo extract 80-mg fixed-dose tablet was administered and, in the other period, ticlopidine 250-mg and ginkgo extract 80-mg tablets were concomitantly administered. A 7-day washout separated the 2 periods. For analysis of pharmacokinetic properties, including C max , T max , t ½ , AUC 0−∞ , and AUC 0−last , serial blood sampling was performed up to 48 hours after study drug administration during each period. Ticlopidine concentrations in plasma were determined by a validated method using LC-MS/MS. In order for the 2 treatments to be considered bioequivalent, the 90% CI of the geometric means ratios for C max and AUC needed to be between 80% and 125%. Bleeding time was determined before dosing (0 hour) and at 5 and 24 hours after dosing. Adverse events (AEs) were identified through patient interview, recording of blood pressure, heart rate, and body temperature, physical examination, 12-lead ECG, and laboratory assessments. Results: Twenty-four healthy Korean male subjects (mean [range] age, 23.9 [22–38] years; height, 174.0 [162–184] cm; weight, 67.4 [56–80] kg) completed the study. Median (range) T max of ticlopidine was 1.5 (0.5–2.0) hours in both groups. The mean (SD) t ½ of ticlopidine in the combined fixed-dose formulation and the concomitant administration groups was 19.5 (3.4) and 19.0 (3.3) hours after study drug administration, respectively. The geometric means ratios of ticlopidine AUC 0−last , AUC 0–∞ , and C max between the combined fixed-dose formulation and concomitant administration were 1.04 (90% CI, 0.96–1.13), 1.04 (90% CI, 0.96–1.13), and 1.09 (90% CI, 0.96–1.23), respectively. The mean (SD) bleeding time at predose (0), and 5 and 24 hours after dose administration was 4.5 (1.6) to 5.4 (1.7) minutes in the combined fixed-dose formulation group and 4.4 (1.6) to 5.1 (1.1) minutes in the concomitant administration group. Five subjects (3 in the combined fixed-dose formulation group and 2 in the concomitant administration group) had bleeding times >8 minutes, but this was not considered to be clinically significant. A total of 24 AEs were reported in 13 of 24 subjects: nausea (3 cases), diarrhea (3), dizziness (3), epigastric discomfort (2), headache (2), rhinorrhea (2), purulent sputum (2), dyspepsia (1), upper abdominal pain (1), cough (1), pharyngolaryngeal pain (1), oropharyngeal swelling (1), dysphonia (1), and dysphagia (1). All were considered mild or moderate in nature. There was no statistically significant difference between the 2 treatments in the number of AEs or in the number of subjects who reported an AE. Conclusion: Administration of a single dose of a combined fixed-dose formulation of ticlopidine 250 mg/ ginkgo extract 80-mg tablets and concomitant administration of ticlopidine and ginkgo extract tablets did not result in statistically significant differences in the pharmacokinetics of ticlopidine in these healthy Korean male volunteers

Background: Mirodenafil is a phosphodiesterase type 5 (PDE-5) inhibitor developed for the treatment of erectile dysfunction. Mirodenafil has the possibility of being administered with alcohol. Objective: This study assessed the hemodynamic effects and pharmacokinetic properties of mirodenafil administered with alcohol. Methods: This single-dose, randomized-sequence, open-label, crossover study was conducted in healthy male volunteers at the Clinical Trials Center, Seoul National University Hospital, Seoul, Korea. Volunteers were randomly allocated to 1 of 3 randomized-sequence groups, each of which consisted of 3 administration phases, each separated by a 1-week washout period: oral mirodenafil 100 mg, alcohol 0.5 g/kg, and both. Vital signs (systolic blood pressure [SBP], dia-stolic BP [DBP], and pulse rate) were measured before (baseline) and at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, and 24 hours after administration. Because volunteers were given a standardized meal at 4 hours after mirodenafil and/or alcohol administration, hemody-namic results were assessed using the maximum decrease from baseline during a period of up to 4 hours after administration. For pharmacokinetic assessment, serial blood samples were collected before (baseline) and at 0.5, 1, 1.25, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours after administration. Tolerability was assessed using monitoring of adverse events (AEs), clinical laboratory parameters, and results of 12-lead electrocardiography. Results: A total of 20 subjects participated in the study (mean [range] age, 25.5 years [20–41 years]; weight, 69.8 kg [57.4–87.2 kg]; and height, 174.7 cm [168–186 cm]). Up to 4 hours after the administration of mirodenafil, alcohol, and mirodenafil + alcohol, the mean (SD) maximum decreases in SBP were 8.5 (3.5), 13.5 (7.8), and 15.1 (6.7) mm Hg, respectively, and the maximum decreases in DBP were 6.4 (4.8), 13.3 (7.4), and 13.8 (5.2) mm Hg. Simultaneous administration of mirodenafil + alcohol was associated with additional mean (95% CI) decreases in SBP and DBP of 1.7 mm Hg (−6.0 to 2.6 mm Hg) and 0.6 mm Hg (−4.7 to 3.6 mm Hg) compared with alcohol alone. Pharmacokinetic parameters of mirodenafil were not significantly different when the drug was administered with or without alcohol. The mean (SD) AUC 0−t values were 842.0 (434.7) ng/mL/h with mirodenafil and 833.4 (398.2) ng/mL/h with mirodenafil + alcohol. The most common AEs considered at least possibly related to study drug were nasal congestion (7 subjects [35%]), headache (3 [15%]), nausea (1 [5%]), and hiccups (1 [5%]). Conclusions: The concurrent administration of mirodenafil with alcohol was not associated with clinically significant hemodynamic changes in these healthy male volunteers in Korea. The pharmacoki-netics of mirodenafil were not significantly altered by this concurrent administration. Mirodenafil administered with alcohol had a tolerability profile comparable to that of mirodenafil alone.

Macitentan is a novel dual endothelin (ET)-1 receptor antagonist to be used in patients with pulmonary arterial hypertension. This study aimed to assess the pharmacokinetics (PK) and pharmacodynamics (PD) of macitentan after administration of multiple doses to healthy Korean male subjects. A randomized, double-blind, placebo-controlled, multiple-ascending dose study was performed in 30 healthy male subjects receiving oral macitentan (3, 10, or 30 mg) or placebo once daily for 10 days. Plasma concentrations of macitentan, its active metabolite ACT-13277, and ET-1 were evaluated. Safety and tolerability measurements were conducted throughout the study. The concentration–time profile of macitentan was characterized by slow absorption (median time to maximum plasma concentration [t max] 9–10 h) and slow elimination (mean elimination half-life [t ½] 11–15 h). After repeated doses of 3, 10, and 30 mg of macitentan over the course of 10 days, the peak concentration (C max) increased as the dose increased and the area under the plasma concentration–time curve during the dosing interval (AUC τ ) increased in a dose-proportional manner. Plasma concentrations showed approximately 1.5- to 1.9-fold accumulation on day 10 compared with day 1. ACT-132577 showed higher levels of exposure than macitentan, its mean half-life was 46–48 h, and it accumulated 7- to 12-fold. Macitentan increased plasma ET-1 concentrations at all doses tested and was well tolerated and elicited no serious adverse events. Multiple oral doses of 3, 10, and 30 mg of macitentan were well tolerated in healthy Korean subjects, and its pharmacokinetics correlated positively with ET-1 concentrations.

Tolvaptan is a selective arginine vasopressin V2-receptor antagonist that is used as an aquaretic agent. This trial investigated the pharmacokinetics and pharmacodynamics of 15- to 60-mg single oral doses of tolvaptan in healthy Korean men. A dose block-randomized, placebo-controlled, double-blind, single ascending dose trial was conducted with 46 subjects receiving tolvaptan (15, 30, or 60 mg) or placebo. To determine pharmacokinetics and pharmacodynamics, blood and urine samples were collected at baseline and up to 48 hours after drug administration. Urine volume and fluid intake were measured for 24 hours starting the day before dosing (day -1) as baseline, and on the day of drug administration (day 1). Tolvaptan showed dose-linear pharmacokinetic characteristics regarding area under the concentration-time curve. Changes from baseline in 24-hour urine volume and 24-hour fluid balance correlated significantly with area under the concentration-time curve from time 0 to the last measurable time. Dose-dependent increases were observed in serum osmolality, serum sodium concentration, and free water clearance in the 4- to 8-hour interval after dosing, and these increases were maintained for at least 24 hours. Single 15- to 60-mg doses of tolvaptan exhibited linear pharmacokinetics and resulted in substantial, dose-dependent aquaresis in healthy Korean men.

Background The biosimilar is a recombinant dimeric tumor necrosis factor receptor (TNFR) under development for the treatment of rheumatoid arthritis. Objective The aim of this study was to compare the pharmacokinetics and/or tolerability of branded etanercept and its biosimilar in healthy Korean men before investigating the clinical efficacy of the biosimilar in subjects. Methods Etanercept (reference, 25 mg) or its biosimilar (test, 25 mg) was subcutaneously injected to the periumbilical area of healthy volunteers in a randomized, open-label, single-dose, active-controlled, two-sequence, crossover study. Plasma concentrations of TNFR in serial blood samples for 480 hours after dosing were measured by ELISA. The primary outcome, pharmacokinetic characteristics, was assessed via geometric mean ratios (GMRs) of the log-transformed pharmacokinetic parameters. The second outcome, tolerability, was evaluated using physical examinations, electrocardiograms, clinical laboratory tests, vital sign measurements, and adverse events (AEs) by unmasked investigators. Results Twenty-three men of mean age (%CV) 25.8 years (17.1%) and weight 70.5 kg (12.8%) were administered study medication. Four subjects dropped out after the first period; their data were included in the analysis. Both test and reference drugs were absorbed with a median T max of 72 (range, 36–144) hours and eliminated with mean (%CV) t ½ of 92.7 (20.9%) and 87.4 (16.6%) hours, respectively. The GMRs (90% CIs) of the test to reference drug for C max , AUC 0–t , and AUC 0–∞ were 0.99 (0.83–1.17), 0.95 (0.79–1.13), and 0.95 (0.80–1.13), respectively. Eleven of 21 (52.4%) and 8 of 21 (38.1%) subjects administered the test and reference drugs reported 22 and 21 AEs, respectively. Common AEs were headache (14.3%), throat irritation (8.5%), and epistaxis (9.5%). Three serious AEs related to a traffic accident (back, neck, and musculoskeletal pain) were reported in a test drug–treated subject. Conclusions In this select group of Korean healthy male volunteers, the reference drug and the test biosimilar met the standard criteria for assuming bioequivalence as defined by Korean regulatory authorities. Because the reference drug is a biological product, further trials for assessment of its efficacy are still required by Korean authorities. World Health Organization International Clinical Trials Registry Platform identifier: KCT0000118

Fimasartan (BR-A-657) is a new angiotensin II receptor antagonist used as antihypertensive agent. The objective of this study was to investigate the effect of the coadministration of fimasartan and amlodipine on the steady-state pharmacokinetics of each drug.This study comprised 2 separate parts, A and B; each was a multiple-dose, open-label, 2-period crossover study in healthy male volunteers. In part A, 20 subjects were administered 120 mg of fimasartan alone in period I and fimasartan with 10 mg of amlodipine in period II. In part B, 14 subjects were administered amlodipine alone, followed by coadministration with fimasartan. Blood samples for pharmacokinetics were collected up to 24 hours after the last dosing. The pharmacokinetics of the coadministration of fimasartan and amlodipine were compared with that of each drug alone.The geometric mean ratio and 90% confidence intervals for C(max,ss) and area under the plasma concentration-time curve (AUC)(τ,ss) of fimasartan (with/without amlodipine) were 1.096 (0.746-1.610) and 1.163 (1.001-1.351), respectively. The geometric mean ratios (90% confidence interval) for C(max,ss) and AUC(τ,ss) of amlodipine (with/without fimasartan) after coadministration with fimasartan were 1.037 (0.969-1.110) and 0.975 (0.920-1.033), respectively.Coadministration of fimasartan and amlodipine did not result in clinically relevant changes in the systemic exposure of fimasartan or amlodipine.

Flecainide acetate is a class Ic antiarrythmic agent that is metabolized by the cytochrome P450 (CYP) 2D6 isozyme. A previous open-label, 2-period, single-sequence crossover study in healthy Korean male volunteers found differences in the pharmacokinetics of flecainide between subjects with the CYP2D6 wild-type allele and those with the CYP2D6*10 allele, as well as differences in the pharmacokinetic interaction between flecainide and the CYP2D6 inhibitor paroxetine between genotype groups.This study evaluated QTc-interval changes after administration of a single oral dose of flecainide, with and without paroxetine, in relation to CYP2D6 genetic polymorphism.This was a follow-on to the previous pharmacokinetic study and used data from the same group of healthy Korean male volunteers. Subjects were grouped by CYP2D6 genotype as follows: CYP2D6*1/*1 or CYP2D6*1/*2 (group 1, extensive metabolizers); CYP2D6*1/*10 (group 2, intermediate metabolizers); and CYP2D6*10/*010 or CYP2D6*10/*36 (group 3, poor metabolizers). Flecainide 200 mg was administered on day 1 (period 1); after a 7-day washout period, subjects received paroxetine 20 mg once daily from day 8 to day 14, and flecainide 200 mg on day 15 (period 2). On days 1 and 15, serial 12-lead ECGs were obtained before flecainide dosing and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours after dosing. Baseline ECGs were obtained at the same time points on days -1 and 14. Machine-read changes in the QT interval corrected using the Fridericia formula (QTcF) and manually read changes in the QT interval individually corrected using mixed-effects modeling (QTcI) from time-matched baseline were analyzed by genotype and by period (baseline and paroxetine-inhibited state). The QRS duration and JTc interval (QTcF - QRS) were also determined.Twenty-one healthy volunteers (mean [SD] age, 24.5 [3.0] years; mean height, 173.5 [4.6] cm; mean weight, 69.1 [4.5] kg), 7 in each group, were enrolled in and completed the study. In period 1, all genotype groups had significant increases from time-matched baseline in both the QTcF interval (group 1:17.4 milliseconds [90% CI, 9.9-24.9], P0.001; group 2: 11.1 milliseconds [90% CI, 7.9-14.3], P = 0.013; and group 3: 20.5 milliseconds [90% CI, 12.8-28.2], P0.001) and the QTcI interval (group 1:15.4 milliseconds [90 % CI, 8.0-22.9], P = 0.001; group 2: 9.1 milliseconds [90% CI, 6.5-11.8], P = 0.030; and group 3:16.4 milliseconds [90% CI, 9.3-23.5], P = 0.001); the extent of increase did not differ significantly between groups. In groups 1 and 2, the least squares mean difference between period 1 and period 2 was statistically significant for the change in QTcF interval (6.5 milliseconds [90 CI, 3.2-9.8], P = 0.002; and 6.7 milliseconds [90% CI, 3.6-9.7], P = 0.001, respectively) and QTcI interval (6.9 milliseconds [90% CI, 4.1-9.8], P0.001; and 5.8 milliseconds [90% CI, 3.4-8.3], P0.001). In group 3, the least squares mean difference between period 1 and period 2 was statistically significant for the change in QTcI interval (3.9 milliseconds [90% CI, 1.3-6.5], P = 0.015) but not for the change in QT cF interval. The changes in QRS duration did not differ significantly by genotype or period. Consistent with the findings for the QTc interval, the least squares mean difference between period 1 and period 2 was statistically significant for the change in JTc interval in groups 1 and 2 (6.9 milliseconds [90% CI, 3.7-10.2], P = 0.001; and 5.4 milliseconds [90% CI, 2.7-8.2], P = 0.001, respectively) but not in group 3.The extent of drug interaction between flecainide and paroxetine, as reflected in the change in QTc interval (used as a pharmacodynamic biomarker), was influenced by the CYP2D6*10 allele in these healthy Korean male volunteers.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The only existing study of CYP2D6*10-associated alterations in flecainide pharmacokinetics was retrospective. • Paroxetine has been known as a strong inhibitor of CYP2D6. WHAT THIS STUDY ADDS • This study reports that the extent of drug interaction between flecainide and paroxetine is influenced by the CYP2D6*10 allele in healthy subjects, which is frequent in Asians. AIMS The objectives were to evaluate the effect of CYP2D6 genetic polymorphism on the pharmacokinetics of flecainide, and also on the extent of drug interaction with paroxetine as a CYP2D6 inhibitor after a single oral administration in healthy subjects. METHODS An open-label, two-period, single-sequence, cross-over study was performed in 21 healthy Korean male volunteers (seven for CYP2D6*1/*1 or *1/*2, group 1; seven for CYP2D6*1/*10, group 2; seven for CYP2D6*10/*10 or *10/*36, group 3). Subjects were administered 200 mg of flecainide on day 1. After a 7-day wash-out period, subjects were administered 20 mg of paroxetine from day 8 to 14, and 200 mg of flecainide on day 15. Blood sampling was performed up to 72 h after flecainide administration. RESULTS Terminal elimination half-life and mean residence time (MRT) were significantly different among three genotype groups after a single oral administration of flecainide (P = 0.021, 0.011, respectively). Area under the concentration–time curve, terminal elimination half-life and MRT increased significantly after paroxetine co-administration only in groups 1 and 2. CONCLUSIONS This study reports that the extent of drug interaction between flecainide and paroxetine is influenced by the CYP2D6*10 allele in healthy subjects, which is frequent in Asians.

Background and PurposezzCarotid artery stenting (CAS) is emerging as an alternative to carotid endarterectomy for the treatment of carotid artery stenosis (CS), but the effect of CAS on the cognitive function of patients with severe CS has not been fully investigated. The aim of this study was to use comprehensive neuropsychological tests to determine the effect of CAS on cognitive function from baseline to 3 months postprocedure in patients with severe CS. MethodszzThirty-one patients due to undergo CAS due to high-grade CS ( ≥70%) and 11 control subjects who were diagnosed with CS, but who did not undergo CAS, and who visited the clinic or emergency room between February 2009 and February 2012 were recruited consecutively at baseline (i.e., pre-CAS). Follow-up neuropsychological evaluations after 3 months were completed by 23 of the 31 patients who underwent CAS, and by 10 of the 11 control subjects. The primary cognitive outcome was assessed using a neuropsychological test containing subcategories designed to test general cognitive function, attention, visuospatial function, language and related functions, memory, and frontal lobe/executive function. ResultszzOf the 23 patients undergoing CAS who completed the 3-month follow-up tests, 12 had asymptomatic CS. During the 3-month follow-up period, the patients who underwent CAS and those with asymptomatic CS achieved similar results to the control group on all cognitive tests. However, symptomatic CS patients (n=11) who underwent CAS exhibited improvements in visuospatial function (p=0.046) and total Seoul Neuropsychological Screening Battery-Dementia Version scores (p=0.010) in comparison with both the asymptomatic CS patients and the control group. ConclusionszzThe findings of this study suggest that CAS has a positive effect on cognitive function in patients with symptomatic CS over a 3-month follow-up period. A long-term, multicenter, prospective case-control study would be helpful to predict quality of life and prognoses for patients undergoing CAS.