Search

Hyun Chul Kim,1,2 Sangmi Lee,1,2 Siyoung Sung,3 Eunjin Kim,3 In-Jin Jang,1 Jae-Yong Chung4 1Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Republic of Korea; 2Integrated Major in Innovative Medical Science, Seoul National University Graduate School, Seoul, Republic of Korea; 3Dong-A ST Research Institute, Yongin-si, Gyeonggi-do, Republic of Korea; 4Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam-si, Gyeonggi-do, Republic of KoreaCorrespondence: Jae-Yong Chung, Seoul National University College of Medicine and Bundang Hospital, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea, Tel +82-31-787-3955, Fax +82-31-787-4045, Email jychung@snubh.orgBackground: Dapagliflozin formate (DAP-FOR, DA-2811), an ester prodrug of dapagliflozin, was developed to improve the stability and pharmaceutical manufacturing process of dapagliflozin, a sodium-glucose cotransporter-2 inhibitor.Purpose: This study aimed to evaluate the pharmacokinetics (PKs) and safety of dapagliflozin for DAP-FOR compared to those for dapagliflozin propanediol monohydrate (DAP-PDH, Forxiga) in healthy subjects.Methods: This was an open-label, randomized, single-dose, two-period, two-sequence crossover study. The subjects received a single dose of DAP-FOR or DAP-PDH 10 mg in each period, with a 7-day washout. Serial blood samples for PK analysis were collected up to 48 hours after a single administration to determine plasma concentrations of DAP-FOR and dapagliflozin. PK parameters were calculated using a non-compartmental method and compared between the two drugs.Results: In total, 28 subjects completed the study. DAP-FOR plasma concentrations were not detected in all of the blood sampling time points except for one time point in one subject, and the corresponding DAP-FOR plasma concentration in the subject was close to the lower limit of quantification. The mean plasma concentration–time profiles of dapagliflozin were comparable between the two drugs. The geometric mean ratios and its 90% confidence intervals of the maximum plasma concentration and area under the plasma concentration–time curve of dapagliflozin for DAP-FOR to DAP-PDH were within the conventional bioequivalence range of 0.80– 1.25. Both drugs were well-tolerated, with a similar incidence of adverse drug reactions.Conclusion: The rapid conversion of DAP-FOR into dapagliflozin led to the extremely low exposure of DAP-FOR and comparable PK profiles of dapagliflozin between DAP-FOR and DAP-PDH. The safety profiles were also similar between the two drugs. These results suggest that DAP-FOR can be used as an alternative to DAP-PDH.Keywords: prodrugs, dapagliflozin, pharmacokinetics, clinical trial, phase I

CT-P47 is a candidate tocilizumab biosimilar. This study assessed the pharmacokinetic (PK) equivalence of CT-P47 and European Union-approved reference tocilizumab (EU-tocilizumab) in healthy Asian adults. This double-blind, multicenter, parallel-group trial randomized healthy adults (1:1) to receive a single (162 mg/0.9 mL) subcutaneous dose of CT-P47 or EU-tocilizumab. The primary endpoint (Part 2) was PK equivalence by area under the concentration – time curve (AUC) from time zero to last quantifiable concentration (AUC0–last), AUC from time zero to infinity (AUC0–inf), and maximum serum concentration (Cmax). PK equivalence was concluded if 90% confidence intervals (CIs) for the ratios of geometric least-squares means (gLSMs) were within the 80–125% equivalence margin. Additional PK endpoints, immunogenicity, and safety were evaluated. In Part 2, 289 participants were randomized (146 CT-P47; 143 EU-tocilizumab); 284 received study drug. AUC0–last, AUC0–inf, and Cmax were equivalent between CT-P47 and EU-tocilizumab: 90% CIs for the ratios of gLSMs were within the 80–125% equivalence margin. Secondary PK endpoints, immunogenicity, and safety were comparable between groups. CT-P47 demonstrated PK equivalence with EU-tocilizumab and was well tolerated, following a single dose in healthy adults. www.clinicaltrials.gov identifier is NCT05188378. Tocilizumab is a biologic medicine used to treat inflammatory diseases including rheumatoid arthritis. Biosimilars are drugs that are highly similar to an already approved, ‘reference’ biologic medicine. This means that they do not have any differences from the reference product in factors including structure, biologic function, efficacy, and safety, that might affect how well they work in patients. Biosimilars are often available at a lower cost than reference drugs, so their use can provide patients with better access to expensive treatments. There are no approved biosimilars of tocilizumab so far: CT-P47 is currently in development as a potential tocilizumab biosimilar. In the main part of this study, 289 healthy Asian volunteers were randomly allocated to receive a single injection of either CT-P47 or the reference drug, European Union-approved tocilizumab (EU-tocilizumab). The main aim of the study was to find out whether CT-P47 and EU-tocilizumab were equivalent in terms of pharmacokinetics (drug absorption, distribution, metabolism, and excretion by the body). This is part of a standard process required by regulatory authorities to ensure that biosimilars work as well as their reference drugs. Analysis of blood samples taken over 43 days showed that the pharmacokinetic profiles of CT-P47 and EU-tocilizumab were equivalent, after the volunteers received a single dose of either drug. Safety and immunogenicity (immune responses made to the drug) were also comparable between CT-P47 and EU-tocilizumab. While only healthy Asian adults were included, further research comparing CT-P47 with reference tocilizumab will help to ensure that the findings from the study can be applied to broader populations.

Hypertension is more effectively treated with coadministration of 2 or more antihypertensive drugs than with high-dose monotherapy. Therefore, calcium channel blockers, angiotensin II receptor blockers, and thiazides are coadministered to treat hypertension. The objective of this study was to compare the pharmacokinetic (PK) profiles of HCP1401, a fixed-dose combination of amlodipine 5 mg, losartan 100 mg, and chlorthalidone 25 mg, with the separate components (loose combination) of amlodipine/losartan 5/100 mg and chlorthalidone 25 mg. A randomized, open-label, single-dose, 2-way crossover study was conducted. Blood samples for amlodipine and chlorthalidone were collected for up to 144 hours after dosing, whereas those for losartan were collected up to 48 hours after dosing. The PK parameters of these drugs were calculated using a noncompartmental method. Sixty subjects completed the study. The geometric mean ratios and 90% confidence intervals of maximum plasma concentration and area under the concentration-time curve to the last measurable point for amlodipine, losartan, and chlorthalidone were within the conventional bioequivalence range of 0.80 to 1.25. There were no clinically significant changes in safety assessments, and the treatments were well tolerated. The PK characteristics and tolerability profiles of a single oral FDC of amlodipine, losartan, and chlorthalidone were equivalent to those of individual tablets in a loose combination.

Sejung Hwang,1 Dae Young Lee,2 Joo-Youn Cho,1,3 Jae-Yong Chung,4 In-Jin Jang,1 Kyung-Sang Yu,1,3 SeungHwan Lee1 1Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Republic of Korea; 2Drug Metabolism and Pharmacokinetics (DMPK), Drug Evaluation, Dong-A ST Research Institute, Gyonggi-do, Republic of Korea; 3Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea; 4Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam, Republic of KoreaCorrespondence: SeungHwan LeeDepartment of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of KoreaTel +82-2-2072-2343Fax +82-2-2072-0720Email leejh413@snu.ac.krPurpose: DA-8031 is a novel selective serotonin reuptake inhibitor for the treatment of premature ejaculation. This study investigated the pharmacokinetics, safety and tolerability of multiple oral doses of DA-8031. In addition, a genetic analysis was explored to evaluate the effect of genetic polymorphisms on the pharmacokinetics of DA-8031.Subjects and Methods: A dose block-randomized, double-blind, placebo-controlled study was conducted in 3 dose groups with 20, 30 and 40 mg of DA-8031. Healthy male subjects were randomized to DA-8031 or placebo at a 4:1 ratio in each dose group of 10 subjects by oral administration once daily for 7 consecutive days. Serial blood and urine samples were collected for the pharmacokinetic evaluation, and the pharmacokinetic-related genes were analyzed by DMETTM plus. A safety evaluation was conducted including adverse events (AEs) monitoring and 12-lead electrocardiogram (ECG).Results: The plasma DA-8031 concentration reached the maximum concentration (Cmax) in 2.2 to 3.0 h and was eliminated with a mean half-life of 25.5 to 26.7 h at steady state. The accumulation index of DA-8031 ranged 2.3 to 2.8. The systemic exposure of DA-8031 of the CYP2D6 intermediate metabolizer (IM) was significantly higher compared to the CYP2D6 poor metabolizer (PM). There were no clinically significant QTc interval changes, and all the adverse events were mild.Conclusion: After multiple oral doses of DA-8031 20, 30, and 40 mg in this study, the systemic exposure of DA-8031 increased in a more than dose-proportional manner with the increasing doses, and DA-8031 was generally well tolerated. In addition, the genetic polymorphisms of CYP2D6 have an impact on the pharmacokinetics of DA-8031.Keywords: selective serotonin reuptake inhibitors, clinical pharmacology, phase 1 study, pharmacogenomics

Aims Rifampicin is a key drug for the treatment of tuberculosis (TB). Little is known for the relationship between the rifampicin pharmacokinetics and genetic polymorphisms in the Asian population. We aimed to investigate relationship between genetic polymorphism of SLCO1B1 and rifampicin exposure and its impact on clinical outcomes in Korean patients with active pulmonary TB. Methods From February 2016 to December 2019, patients with active pulmonary TB who were taking rifampicin for >1 week were prospectively enrolled. Serial or 1-time blood sampling was conducted to determine rifampicin concentrations. The genotype of 4 single nucleotide polymorphisms of SLCO1B1 was determined. To estimate the drug clearance and exposure, population pharmacokinetics analysis was conducted. Clinical outcomes such as time to acid-fast bacteria culture conversion, chest radiograph score changes from baseline, and all-cause mortality were also evaluated. The exposure among different SLCO1B1 genotype was compared and relationship between drug exposure and clinical outcomes were explored. Results A total of 105 patients (70 males and 35 females) were included in the final analysis. The mean age of patients was 55.4 years. The mean drug clearance and exposure were 13.6 L/h and 57.9 mg h/L, respectively. The genetic polymorphisms of SLCO1B1 were not related to rifampicin clearance or exposure. As the rifampicin exposure increased, the chest radiographs improved significantly, but the duration of acid-fast bacteria culture conversion was not related to the drug exposure. Conclusion SLCO1B1 gene polymorphisms did not influence rifampicin concentrations and clinical outcomes in Korean patients with active pulmonary TB.

AST-001 is an L-isomer of serine that has protective effects on neurological disorders. This study aimed to establish a population pharmacokinetic (PK) model of AST-001 in healthy Korean to further propose a fixed-dose regimen in pediatrics. The model was constructed using 648 plasma concentrations from 24 healthy subjects, including baseline endogenous levels during 24 h and concentrations after a single dose of 10, 20, and 30 g of AST-001. For the simulation, an empirical allometric power model was applied to the apparent clearance and volume of distribution with body weight. The PK characteristics of AST-001 after oral administration were well described by a two-compartment model with zero-order absorption and linear elimination. The endogenous production of AST-001 was well explained by continuous zero-order production at a rate of 0.287 g/h. The simulation results suggested that 2 g, 4 g, 7 g, 10 g, and 14 g twice-daily regimens for the respective groups of 10–14 kg, 15–24 kg, 25–37 kg, 38–51 kg, 52–60 kg were adequate to achieve sufficient exposure to AST-001. The current population PK model well described both observed endogenous production and exogenous administration of AST-001 in healthy subjects. Using the allometric scaling approach, we suggested an optimal fixed-dose regimen with five weight ranges in pediatrics for the upcoming phase 2 trial.

Background Amoxicillin/clavulanate is a widely used oral formulation of penicillin combined with a β-lactamase inhibitor. When using amoxicillin/clavulanate in the elderly, the risk of adverse drug reaction may be greater. This study aimed to evaluate the pharmacokinetics (PKs) and safety of multiple-dose amoxicillin/clavulanate administration in healthy elderly subjects and to compare the observed PK profiles with those in healthy younger adults. An open-label, one-sequence, multiple administration study was conducted in 16 healthy elderly subjects. Materials and methods Subjects orally received amoxicillin and clavulanate 750/187.5 twice daily for 9 days. For PK analysis, serial blood samples were collected up to 12 hours after the last administration of amoxicillin/clavulanate. The demographic and PK data of this study were compared to those of healthy young adults from a separate study with a similar design. Safety assessments including clinical laboratory tests, physical examination, vital signs, and adverse event (AE) monitoring were performed throughout the study. Results All AEs were mild, and no serious AEs were reported in this study. The systemic exposure of amoxicillin and clavulanate was ~ 90% and 60% higher, respectively, in the elderly subjects than in the younger subjects. However, the time required to reach maximum concentration at steady state and the elimination half-life were similar in the two age groups. Conclusion Although multiple administration of amoxicillin/clavulanate 750/187.5 mg was safe and well-tolerated, the systemic exposure of amoxicillin and clavulanate was higher in elderly subjects than in younger subjects.

Ursodeoxycholic acid (UDCA) is a secondary bile acid component used for treating primary biliary cirrhosis. This study evaluated and compared the pharmacokinetic (PK) profiles of UDCA and its conjugates glyco-UDCA (G-UDCA) and tauro-UDCA (T-UDCA) in healthy elderly subjects and younger adults. In this randomized, open-label, 2-treatment, 1-sequence, and parallel study, subjects received 400 or 800 mg UDCA on day 1, followed by 200 mg UDCA twice daily for 2 weeks. Blood samples were obtained up to 24 hours after the first UDCA dose. Changes in miRNA-122, γ-glutamyl transferase, aspartate aminotransferase, and alanine aminotransferase levels from baseline were assessed to determine the safety and pharmacological effects of UDCA. This study examined the outcomes of 16 elderly subjects and 16 younger adults. Dose-normalized peak concentration of and systemic exposure to UDCA were 2 to 4 times higher, and the corresponding values of G-UDCA and T-UDCA were 1.7 times higher in the elderly subjects than in the younger adults. The subjects in both groups showed multiple peak profiles of UDCA and its conjugates. The miRNA-122 levels and hepatic enzyme test results were within the normal range in the elderly subjects after multiple administration of UDCA. This study is the first to confirm that the PK measurements of UDCA were higher in elderly subjects than in younger adults, which may improve the clinical outcomes of elderly subjects.

Sorafenib, an oral multikinase inhibitor, exhibits a highly variable absorption profile due to enterohepatic reabsorption and poor solubility. SYO-1644 improved the solubility of sorafenib by nanoparticulation technology leading to enhanced bioavailability. To evaluate the pharmacokinetically equivalent dose of SYO-1644 to the reference Nexavar® 200 mg, a randomized, open-label, replicated two-period study was conducted in healthy volunteers. A total of 32 subjects orally received a single dose of the following assigned treatment under a fasted state in the first period and repeated once more in the second period with a two-week washout: SYO-1644 100, 150 and 200 mg and Nexavar® 200 mg. Pharmacokinetic (PK) samples were collected up to 168 h post-dose. The PK profile was evaluated by both non-compartmental analysis and population PK method. With the final model, 2 × 2 crossover trial scenarios with Nexavar® 200 mg and each dose of SYO-1644 ranging from 100 to 150 mg were repeated 500 times by Monte Carlo simulation, and the proportion of bioequivalence achievement was assessed. Transit absorption compartments, followed by a one-compartment model with first-order elimination and enterohepatic reabsorption components were selected as the final model. The simulation results demonstrated that the SYO-1644 dose between 120 and 125 mg could yielded the highest proportion of bioequivalence.

Combination therapy of pregabalin and tramadol is used to treat chronic neuropathic pain; however, the pharmacokinetic (PK) interactions of these drugs has not been studied. This study aimed to evaluate PK interactions between pregabalin and tramadol and the safety of combination therapy. A randomized, open-label, multiple-dose, three-treatment, three-period, six-sequence cross-over study was conducted in healthy subjects. All subjects received the following three treatments for 4 days in each period: pregabalin 150 mg twice daily; tramadol extended-release (ER) 200 mg in the morning, and 100 mg in the evening; and co-administration of pregabalin 150 mg and tramadol ER 200 mg in the morning, and pregabalin 150 mg and tramadol ER 100 mg in the evening. A total of 21 subjects completed the study with no clinically significant safety issues. For pregabalin, the geometric mean ratio (GMR) (90% CI; confidence interval) of combination therapy to monotherapy for maximum concentration at steady state (Cmax,ss) and area under the concentration curve from 0 to dosing interval time at steady state (AUCτ,ss) were 0.8801 (0.8043–0.9632) and 1.0830 (1.0569–1.1098), respectively. The corresponding values for tramadol were 1.0177 (0.9839–1.0526) and 1.0152 (0.9896–1.0414), respectively. The GMR (90% CI) of combination therapy to monotherapy of O-desmethyl-tramadol for Cmax,ss and AUCτ,ss was 1.0465 (1.0095–1.0848) and 1.0361 (1.0001–1.0734), respectively. There were no significant drug interactions between pregabalin and tramadol, considering that all of the 90% CI of PK measures were within the conventional bioequivalence range. Both drugs were well tolerated when administered concomitantly.

Jung Sunwoo,1 Yu Kyong Kim,1 Yewon Choi,1 Kyung-Sang Yu,1 Heesook Nam,2 Young Lag Cho,2 Seonghae Yoon,3 Jae-Yong Chung3 1Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, 2LegoChem Biosciences, Inc., Daejeon, 3Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam, Republic of Korea Background: LCB01-0371 is a novel oxazolidinone antibiotic that blocks protein production by binding to bacterial 23S ribosomes. This antibiotic is active against Gram-positive bacteria. This study aimed to evaluate the effect of food on the pharmacokinetics (PKs) of LCB01-0371 and evaluate its safety profile.Subjects and methods: A randomized, open-label, two-way crossover study was performed in 18 healthy Korean male subjects. All subjects received a single oral 800mg dose of LCB01-0371 in each period under fed or fasting condition with a 7-day washout in between. The fed condition was defined as consumption of a meal of 800–1,000kcal containing ~50% of fat content. Serial blood samples were collected over 24h after dosing, and the PK parameters were calculated by noncompartment analysis. All available data of the subjects who received LCB01-0371 at least once were included in the safety data summaries.Results: In the fed condition, both the maximum plasma concentration (Cmax) and the total systemic exposure (area under the plasma concentration–time curve from time zero to the last observed time point [AUClast]) decreased by ~33% and 10%, respectively. The time to reach Cmax was delayed by ~1.25h in the fed condition, whereas the mean elimination half-life remained similar in both conditions. In the fed/fasting condition, the geometric mean ratios and 90% CI of the Cmax and AUClast were 0.666 (0.470–0.945) and 0.897 (0.761–1.057), respectively. There were no drug-related adverse events (AEs) or serious AEs.Conclusion: Although the Tmax after a single oral 800mg dose of LCB01-0371 was slightly delayed under the fed condition compared to the fasting condition, the total systemic exposure was similar under both conditions. Therefore, LCB01-0371 could be administered regardless of food intake. Keywords: antibiotic resistance, gram-positive bacteria, clinical trial

Metformin, an oral hypoglycemic agent belonging to biguanide class, is widely used to treat type 2 diabetes mellitus, and several drug transporters such as organic cation transporters (OCTs), multidrug and toxin extrusion transporter (MATE), and plasma membrane monoamine transporter (PMAT) are thought to affect its disposition. We evaluated the role of PMAT genetic variations on the pharmacokinetic characteristics of metformin in a Korean population. In this retrospective study, 91 healthy subjects from four different metformin pharmacokinetic studies were analyzed; in each study, the subjects were administered two oral doses of metformin at intervals of 12 hours and dose-normalized pharmacokinetic parameters were compared between the subjects' genotypes. Subjects who had more than one allele of c.883-144A>G single nucleotide polymorphism (SNP) in PMAT gene (rs3889348) showed increased renal clearance of metformin compared to wild-type subjects (814.79 ± 391.73 vs. 619.90 ± 195.43 mL/min, p=0.003), whereas no differences in metformin exposure were observed between the PMAT variant subjects and wild-type subjects. Similarly, subjects with variant rs316019 SNP in OCT2 showed decreased renal clearance of metformin compared to wild-type subjects (586.01 ± 160.54 vs. 699.13 ± 291.40 mL/min, p=0.048). Other SNPs in PMAT and MATE1/2-K genes did not significantly affect metformin pharmacokinetics. In conclusion, the genetic variation of c.883-144A>G SNP in PMAT significantly affects the renal clearance of metformin in healthy Korean male subjects.

Background LCB01-0371 is a new oxazolidinone antibiotic, which targets most Gram-positive organisms. High rates of adverse reactions including myelosuppression have been reported for existing oxazolidinones, limiting their long-term use. Objectives The safety, tolerability and pharmacokinetics (PK) of 21 day multiple oral administrations of LCB01-0371 in healthy male subjects (clinicaltrials.gov: NCT02540460) were investigated. Methods In this randomized, double-blind, placebo-controlled study, subjects received 800 mg of LCB01-0371 once or twice daily or 1200 mg of LCB01-0371 twice-daily for 21 days in a fasting state. Safety and tolerability profiles including laboratory tests were evaluated during the study and on a post-study visit and the results were analysed using repeated-measures analysis of variance (RM-ANOVA). Serial blood samples for PK analysis were collected up to 12 h after dosing on day 21. Results A total of 40 subjects were enrolled and 34 subjects completed the study. Two subjects dropped out according to stopping rules. In the 1200 mg twice-daily dose group, the absolute value of red blood cell count, haematocrit and haemoglobin decreased by 500 × 106/L (6.5%), 4.5% (6.8%) and 1.6 g/dL (6.9%), respectively, after 21 day administrations of LCB01-0371. However, mean relative changes from baseline of all haematology values were not significantly different among doses, including placebo (all, P

Deok Yong Yoon,1 Sang-In Park,2 Jin-A Jung,3 Yong-Il Kim,3 In-Jin Jang,1 Jae-Yong Chung4 1Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Republic of Korea; 2Department of Clinical Pharmacology and Therapeutics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea; 3Hanmi Pharm. Co., Ltd., Seoul, Republic of Korea; 4Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam, Republic of KoreaCorrespondence: Jae-Yong ChungDepartment of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, 82, Gumi-ro, 173 Beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of KoreaTel +82-31-787-3955Fax +82-31-787-4045Email jychung@snubh.orgBackground: A fixed-dose combination (FDC) tablet formulation of amlodipine/losartan/rosuvastatin 5/100/20 mg was developed to improve medication compliance in patients with both hypertension and dyslipidemia. The comparative pharmacokinetic study was performed to compare the profile of an FDC tablet formulation of amlodipine/losartan/rosuvastatin with that of concomitant administration of a currently marketed FDC tablet of amlodipine/losartan with a rosuvastatin tablet.Subjects and Methods: A randomized, open-label, single oral dose, two-way crossover study was conducted in 60 healthy subjects. Subjects were orally administered the FDC tablet of amlodipine/losartan/rosuvastatin and a loose combination (LC) of two tablets comprising an FDC of amlodipine/losartan and rosuvastatin. Blood samples were collected for up to 144 h post dose for pharmacokinetic evaluations. Plasma concentrations of amlodipine, losartan, EXP3174 (an active metabolite of losartan), and rosuvastatin were measured by using liquid chromatography-tandem mass spectrometry. The geometric mean ratio (GMR) and its 90% confidence interval (90% CI) in the FDC treatment to LC treatment for the area under the concentration-time curve from zero to the last quantifiable time point (AUClast) and the maximum plasma concentration (Cmax) were calculated. Safety was monitored throughout the study.Results: The GMR (90% CI) values of AUClast and Cmax were 0.9946 (0.9663– 1.0238) and 0.9690 (0.9379– 1.0011) for amlodipine, 0.9855 (0.9422– 1.0308) and 0.9178 (0.8349– 1.0089) for losartan, 0.9814 (0.9501– 1.0136) and 0.9756 (0.9313– 1.0219) for EXP3174, and 0.9448 (0.8995– 0.9923) and 0.9609 (0.8799– 1.0494) for rosuvastatin, respectively. No clinically significant changes were observed in any of the safety parameters, including clinical laboratory tests, vital signs, electrocardiograms, and physical examinations, between the FDC treatment and the LC treatment.Conclusion: We confirmed the pharmacokinetic equivalence of the FDC and LC treatments. This triple combination FDC formulation could be a clinically useful replacement for LC therapy.Keywords: fixed-dose combination, loose combination, bioequivalence, pharmacokinetics, hypertension, dyslipidemia

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.

Purpose Human multidrug and toxin extrusion member 1 (MATE1, SLC47A1) and Organic Cation Transporter 2 (OCT2, SLC22A2) play important roles in the renal elimination of various pharmacologic agents, including the anti-diabetic drug metformin. The goal of this study was to determine the association between metformin's pharmacokinetics and pharmacodynamics and the genetic variants of MATE1 (rs2289669) and OCT2 (rs316019) before and after treatment with the potential MATE inhibitor, ranitidine. Methods We recruited 26 healthy Koreans balanced across the OCT2 and MATE1 genetic variants, and conducted a prospective clinical trial to investigate their effects on metformin's pharmacokinetics and pharmacodynamics before and after ranitidine treatment. Results Neither MATE1 rs2289669 nor OCT2 rs316019 affected metformin's pharmacokinetics and pharmacodynamics before ranitidine treatment. However, the renal clearance of metformin was significantly higher (15.2%) after ranitidine treatment in the MATE1 GG group compared with the MATE1 GA + AA group. Only the effect of MATE1 on the renal clearance of metformin after ranitidine treatment was significant (b = -0.465, p ≤ 0.05) after including demographic data and the OCT2 genotype in the model. Conclusion Our study suggests that MATE1 rs2289669 may be a significant determinant in the renal clearance of metformin in the case of transporter-mediated drug interactions.

Background Metformin and dipeptidyl peptidase-4 (DPP-IV) inhibitors are commonly combined to treat patients with diabetes mellitus (DM). A new fixed-dose combination (FDC) drug containing gemigliptin, a DPP-IV inhibitor, and sustained-release metformin has been developed. This study aimed to compare the PKs and tolerability of FDC versus loose combination of gemigliptin 50 mg and metformin 500 mg. Materials and methods A randomized, open-label, two-treatment, two-period, two-sequence, crossover study was conducted in 28 healthy subjects, who received a single oral dose of an FDC tablet of gemigliptin (50 mg) and sustained-release metformin (500 mg) or were coadministered gemigliptin (50 mg) and extended-release metformin (500 mg) with a 1-week washout. Serial blood samples were collected up to 48 hours after study drug administration, and the plasma concentrations of gemigliptin, LC15-0636 (active metabolite of gemigliptin), and metformin were determined using a validated LC-MS/MS method. Pharmacokinetic parameters were derived using a noncompartmental method. Safety and tolerability were evaluated based on vital signs, adverse events, clinical laboratory tests, and electrocardiography. Results The concentration-time profiles of gemigliptin and metformin were similar when they were administered as FDC or were coadministered. The geometric mean ratio (GMR) and its 90% CIs of Cmax for gemigliptin, LC15-0636, and metformin were 0.93 (0.85 - 1.02), 1.00 (0.94 - 1.06), and 1.03 (0.98 - 1.09), respectively. The corresponding values of AUClast were 0.97 (0.93 - 1.01), 1.00 (0.97 - 1.04), and 1.00 (0.95 - 1.05), respectively. There were no clinically meaningful differences in safety and tolerability. Conclusion When comparing the AUClast and Cmax of gemigliptin, LC15-0636, and metformin, the 90% CIs were all within the range of 0.8 - 1.25, which is the commonly accepted range for evaluating bioequivalence.

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.

Ursodeoxycholic acid (UDCA) is a metabolic by-product of intestinal bacteria, showing hepatoprotective effects. However, its underlying molecular mechanisms remain unclear. The purpose of this study was to elucidate the action mechanisms underlying the protective effects of UDCA and vitamin E against liver dysfunction using metabolomics and metagenomic analysis. In this study, we analysed blood and urine samples from patients with obesity and liver dysfunction. Nine patients were randomly assigned to receive UDCA (300 mg twice daily), and 10 subjects received vitamin E (400 IU twice daily) for 8 weeks. UDCA significantly improved the liver function scores after 4 weeks of treatment and effectively reduced hepatic deoxycholic acid and serum microRNA-122 levels. To better understand its protective mechanism, a global metabolomics study was conducted, and we found that UDCA regulated uremic toxins (hippuric acid, p-cresol sulphate, and indole-derived metabolites), antioxidants (ascorbate sulphate and N-acetyl-L-cysteine), and the phenylalanine/tyrosine pathway. Furthermore, microbiome involvement, particularly of Lactobacillus and Bifidobacterium, was demonstrated through metagenomic analysis of bacteria-derived extracellular vesicles. Meanwhile, vitamin E treatment did not result in such alterations, except that it reduced uremic toxins and liver dysfunction. Our findings suggested that both treatments were effective in improving liver function, albeit via different mechanisms.

It is not currently possible to rapidly estimate the extent of hepatocyte loss during drug-induced liver injury (DILI). We used a proprietary mechanistic model (DILIsym) to estimate percentage hepatocyte loss due to DILI that resulted from four different patterns of serum alanine aminotransferase (ALT) over time: rapid onset and rapid decrease in ALT levels, moderate onset and moderate decrease in ALT levels, moderate onset and extended duration (over 1 month) of ALT elevations, and an ALT profile with multiple peaks. Using these data, we derived a novel parameter, PALT = ALT_AUC*Peak ALT0.18 /105 ((IU/L)2 *h), where AUC is area under the curve, that correlated well with hepatocyte loss estimates derived by DILIsym in patients with DILI due to six different hepatotoxic drugs. Although further validation will be required, the fact that PALT can be derived rapidly using publicly available pharmacokinetic software may make it a useful parameter to improve the safety of drugs.

Age-related physiological changes are known to alter the pharmacokinetics (PK) and pharmacodynamics (PD) of drugs. Metformin is commonly used as first-line medication for management of diabetes in elderly patients. However, the PK and PD of metformin have not been sufficiently studied in elderly subjects. Here, 12 elderly subjects, aged 65 to 85 years, and 20 younger healthy volunteers were orally administered 750 mg of metformin 2 hours after dinner, followed by administration of a second dose (500 mg) 12 hours later. An oral glucose tolerance test (OGTT) was performed 2 hours after the second dose, with 75 g of glucose administered. Blood samples were collected at specific time points after the second metformin dose for the assessment of PK and the glucose-lowering effect of metformin. Elderly subjects exhibited 1.7 and 2.0 times higher average Cmax and AUC∞ than the younger subjects, respectively (P = .007 and .001, respectively), and t1/2 was comparable between the elderly and younger subjects. However, relative glucose level changes from baseline after metformin administration tended to be lower in elderly subjects. Systemic exposure to metformin was elevated by 50% or more in elderly subjects, whereas the glucose-lowering effect was similar compared to younger subjects after 2 doses of metformin.

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

Therapeutic drug monitoring (TDM) of second-line antituberculosis drugs would allow for optimal individualized dosage adjustments and improve drug safety and therapeutic outcomes. To evaluate the pharmacokinetic (PK) characteristics of clinically relevant, multidrug treatment regimens and to improve the feasibility of TDM, we conducted an open-label, multiple-dosing study with 16 healthy subjects who were divided into two groups. Cycloserine (250 mg), p -aminosalicylic acid (PAS) (5.28 g), and prothionamide (250 mg) twice daily and pyrazinamide (1,500 mg) once daily were administered to both groups. Additionally, levofloxacin (750 mg) and streptomycin (1 g) once daily were administered to group 1 and moxifloxacin (400 mg) and kanamycin (1 g) once daily were administered to group 2. Blood samples for PK analysis were collected up to 24 h following the 5 days of drug administration. The PK parameters, including the maximum plasma concentration ( C max ) and the area under the plasma concentration-time curve during a dosing interval at steady state (AUC τ ), were evaluated. The correlations between the PK parameters and the concentrations at each time point were analyzed. The mean C max and AUC τ , respectively, for each drug were as follows: cycloserine, 24.9 mg/liter and 242.3 mg · h/liter; PAS, 65.9 mg/liter and 326.5 mg · h/liter; prothionamide, 5.3 mg/liter and 22.1 mg · h/liter; levofloxacin, 6.6 mg/liter and 64.4 mg · h/liter; moxifloxacin, 4.7 mg/liter and 54.2 mg · h/liter; streptomycin, 42.0 mg/liter and 196.7 mg · h/liter; kanamycin, 34.5 mg/liter and 153.5 mg · h/liter. The results indicated that sampling at 1, 2.5, and 6 h postdosing is needed for TDM when all seven drugs are administered concomitantly. This study indicates that PK characteristics must be considered when prescribing optimal treatments for patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT02128308.)

Taegon Hong,1,2 Seunghoon Han,1,2 Jongtae Lee,1,2 Sangil Jeon,1,2 Gab-Jin Park,1,2 Wan-Su Park,1,2 Kyoung Soo Lim,3 Jae-Yong Chung,4 Kyung-Sang Yu,3 Dong-Seok Yim1,2 1Department of Pharmacology, College of Medicine, the Catholic University of Korea, Seoul, Republic of Korea; 2PIPET (Pharmacometrics Institute for Practical Education and Training), the Catholic University of Korea, Seoul, Republic of Korea; 3Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Republic of Korea; 4Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam, Republic of Korea Abstract: A single 400 mg dose of moxifloxacin has been the standard positive control for thorough QT (TQT) studies. However, it is not clearly known whether a 400 mg dose is also applicable to TQT studies in Asian subjects, including Koreans. Thus, we aimed to develop a pharmacokinetic (PK)-pharmacodynamic (PD) model for moxifloxacin, to evaluate the time course of its effect on QT intervals in Koreans. Data from three TQT studies of 33 healthy male Korean subjects who received 400 and 800 mg of moxifloxacin and placebo (water) were used. Twelve-lead electrocardiograms were taken for 2 consecutive days: 1 day to record diurnal changes and the next day to record moxifloxacin or placebo effects. Peripheral blood samples were also obtained for PK analysis. The PK-PD data obtained were analyzed using a nonlinear mixed-effects method (NONMEM ver. 7.2). A two-compartment linear model with first-order absorption provided the best description of moxifloxacin PK. Individualized QT interval correction, by heart rate, was performed by a power model, and the circadian variation of QT intervals was described by two mixed-effect cosine functions. The effect of moxifloxacin on QT interval prolongation was well explained by the nonlinear dose-response (Emax) model, and the effect by 800 mg was only slightly greater than that of 400 mg. Although Koreans appeared to be more sensitive to moxifloxacin-induced QT prolongation than were Caucasians, the PK-PD model developed suggests that a 400 mg dose of moxifloxacin is also applicable to QT studies in Korean subjects. Keywords: thorough QT study, PK-PD model, NONMEM, Emax model

Physiologically based pharmacokinetic (PBPK) modelling and simulation enable researchers to overcome practical limitations for clinical trials on special populations. This study was conducted to investigate how the PBPK model describes the pharmacokinetics of metformin in young adult and elderly populations and to predict the pharmacokinetics of metformin in patients with renal or hepatic impairment in both populations. A first-order absorption/PBPK model for metformin was built in the Simcyp simulator version 14 release 1. A full PBPK model was constructed for metformin based on physicochemical properties and clinical observations. The model was refined and validated using clinical plasma concentration data obtained in healthy young adults and elderly after the oral administration of metformin. Metformin pharmacokinetics in patients with renal or hepatic impairment were then investigated and compared by simulation. The PBPK model reasonably predicted the pharmacokinetic profiles of metformin for both young adults and the elderly. The predicted pharmacokinetic parameters, including maximum concentration, area under the time–concentration curve, and apparent oral clearance values, were within 1.5-fold of the observed data of metformin. In the simulation results, the systemic exposure of metformin was expected to be markedly increased not only with a decrease in renal function but also with severe hepatic impairments. The PBPK model adequately characterised the pharmacokinetics of metformin in both young adult and elderly populations. PBPK modelling and simulation can be used as a useful tool to investigate and compare the pharmacokinetics in geriatric populations incorporating various disease conditions.

VVZ-149, a dual antagonist of GlyT2 and 5HT2 A receptors, is an investigational analgesic with a novel mechanism of action that is currently under early-stage clinical development as an injectable agent for the treatment of postoperative pain. Here, the safety, tolerability, and pharmacokinetics of VVZ-149 injections in healthy male volunteers were explored in a randomized, double-blind, single- and multiple-ascending-dose (SAD and MAD, respectively), placebo-controlled clinical study. Subjects randomly received a 4-hour intravenous infusion of 0.25-8 mg/kg VVZ-149 or placebo in the SAD study (n = 46) or a 4-hour intravenous infusion of 4-7 mg/kg VVZ-149 or placebo twice daily for 3 days in the MAD study (n = 20). Serial blood and urine samples were collected for the pharmacokinetic analysis of VVZ-149 and its active metabolite (VVZ-368). Noncompartmental and compartmental pharmacokinetic analyses were performed. Various dosing scenarios were simulated to identify the adequate dosing regimen for the subsequent trials. Plasma exposure to VVZ-149 and VVZ-368 showed a dose-proportional increase. VVZ-149 did not accumulate in the plasma, whereas the plasma concentration of VVZ-368 increased by 1.23- to 2.49-fold after the fifth and sixth doses, respectively, in the MAD trial. Among the simulated dosing regimens, a loading dose followed by a maintenance dose was found to be an optimal dosing regimen, yielding the effective concentration estimated from animal studies in rat models of neuropathic or inflammatory pain. Single- or multiple-dose administration of VVZ-149 was generally well tolerated. These results showed that 0.5-8 mg/kg VVZ-149 exhibited linear pharmacokinetic characteristics and can be safely administered in further clinical studies.

Aim The organic cation transporter 1 (OCT1) plays a key role in the cellular transport of metformin and its subsequent glucose-lowering effect. A recent non-clinical study reported that metformin uptake into hepatocytes is regulated via OCT1, and that uptake was strongly inhibited by verapamil. Therefore, we investigated the effects of verapamil co-administration on the pharmacokinetics and pharmacodynamics of metformin in humans.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Human multidrug and toxin extrusion member 2 (MATE2-K, SLC47A2) plays an important role in the renal elimination of various clinical drugs including the antidiabetic drug metformin. The goal of this study was to characterize genetic variants of MATE2-K and determine their association with the pharmacokinetics of metformin.We screened DNA samples from 48 healthy Koreans for variants in the promoter and coding regions of MATE2-K and examined the function of common haplotypes in the promoter region using in-vitro luciferase assays. Then, the metformin pharmacokinetic study was carried out to determine the association between MATE2-K promoter haplotypes and metformin pharmacokinetics.Nine variants in the promoter region of MATE2-K and one nonsynonymous variant, p.G211V, were identified. The MATE2-K promoter haplotype 1 containing a known functional polymorphism, g.-130GA and haplotype 2 containing two polymorphisms, g.-609GA and g.-396GA showed a significant increase in reporter activity. Among the 45 individuals who participated in the metformin pharmacokinetic study, 12 healthy Koreans who were homozygous for haplotype 1 or 2 showed a significant increase in renal clearance [539 ± 76 (reference group) vs. 633 ± 102 (variant group) ml/min; P=0.006] and secretion clearance [439 ± 81 (reference group) vs. 531 ± 102 (variant group) ml/min; P=0.007] of metformin compared with that shown by the reference group.Our study suggests that common promoter haplotypes of MATE2-K are associated with the pharmacokinetics of metformin.

Summary: Pitavastatin, a 3-hydroxyl-3-methylglutaryl-coenzyme A reductase inhibitor is distributed to the liver, a target organ of action and excreted mainly into the bile. To investigate the impact of influx (OATP1B1) and efflux (MRP2, BCRP) transporter alleles on its disposition, the pharmacokinetic (PK) parameters were compared among the following groups: SLC01B1 (*15 carrier and non-carrier), ABCC2 (G1249A, C3972T, C–24 T, G1549A, and G1774T), and ABCG2 (C421A) single nucleotide polymorphisms in 45 healthy Korean volunteers. Pitavastatin AUClast was higher in individuals carrying the SLC01B1*15 allele than those not carrying it (144.1 ± 55.3 vs 84.7 ± 25.7 h-ng/mL [mean ± SD], p = 0.002). The AUC last varied significantly according to the ABCC2 C–24 T allele (103.4 ± 42.2, 80.2 ± 23.8, and 39.0 h-ng/mL in CC, CT and TT, respectively; p = 0.027). Other SNPs of ABCC2 and ABCG2 were not significant. The effect of these transporters and body weight on the AUC last and C max were tested, and only SLC01B1 and ABCC2 C–24 T genotypes were significant factors by analysis of covariance. These variants accounted for almost 50% of the variation in AUC last and C max of pitavastatin. Therefore, ABCC2 C–24 T was significantly associated with pitavastatin human PK when the known effect of SLC01B1 *15 was also considered.

The intraocular route of drug administration enables the delivery of high concentrations of therapeutic drugs, while minimizing their systemic absorption. Several drugs are administered into the anterior chamber or vitreous, and the intraocular injection has been effective in curing various intraocular diseases. Rabbit eyes have been widely used for ophthalmic research, as the animal is easy to handle and economical compared to other mammals, and the size of a rabbit eye is similar to that of a human eye. Using a 30 G needle, drugs can be injected into the intracameral and intravitreal spaces of rabbit eyes. The eyeballs are then frozen until analysis, and can be divided into the aqueous humor, vitreous, and retina/choroid. The vitreous and retina/choroid samples can be homogenized and solubilized before analysis. Then, immunoassays can be performed to measure the concentrations of intraocular drugs in each compartment. Appropriate pharmacokinetic models can be used to calculate several parameters, such as the half-life and maximum concentration of the drug. Rabbit eyes can be a good model for pharmacokinetic studies of intraocular drugs.

This study was designed to determine whether genetic polymorphisms of multidrug-resistant protein 2 (ABCC2), organic anion transporting polypeptide 1B1 (SLCO1B1), and breast cancer resistance protein (ABCG2) have an effect on olmesartan pharmacokinetics in Korean subjects. Sixty-eight healthy male volunteers who participated in previous pharmacokinetics studies of olmesartan medoxomil (single dose, 20 mg or 40 mg) were enrolled. All subjects were analyzed and grouped according to the genotypes of ABCC2, SLCO1B1, and ABCG2. The dose-normalized peak plasma concentration (C(max)) and area under the plasma concentration-time curve (AUCt) values were analyzed. The dose-normalized mean C(max) and AUC(t) in the ABCC2 -24CT genotype group were higher than those in the -24CC genotype group [C(max,dn): CT 26.1 ± 6.5 (ng/mL)/mg versus CC 22.1 ± 6.7 (ng/mL)/mg, P = 0.010, AUC(t,dn): CT 178.7 ± 45.6 (hr·ng(-1)·mL(-1))/mg versus CC 149.9 ± 39.8 (hr·ng(-1)·mL(-1))/mg, P = 0.010]. The difference in AUC(t,dn) between the ABCC2 -1549GG and -1549GA genotype groups was statistically significant [GG 149.0 ± 41.0 (hr·ng(-1)·mL(-1))/mg versus GA 174.1 ± 43.3 (hr·ng(-1)·mL(-1))/mg, P = 0.019]. No significant differences were observed for any other single nucleotide polymorphism in ABCC2, SLCO1B1, or ABCG2. The ABCC2 -24CC genotype group exhibited lower systemic exposure of olmesartan than the -24CT genotype group, whereas no significant differences were observed in the other transporter genotype groups.

Summary What is known and Objective: Acarbose, an α-glycosidase inhibitor, is used to treat diabetic patients. Pharmacokinetic evaluation of acarbose is difficult because

The investigators quantified the relationship between the genetic polymorphism of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) and the low-density lipoprotein cholesterol (LDL-C)-lowering effects of atorvastatin in a prospective clinical study. Twenty-four healthy participants were grouped into HMGCR rs3846662 GG (n = 13) and AA (n = 11) genotypes and given atorvastatin (20 mg/d) for 14 days. Serum levels of LDL-C, high-density lipoprotein cholesterol, total cholesterol, triglycerides, and creatinine kinase (CK) were measured before (day 1) and 7, 13, 14, 15, 16, 21, and 28 days after dosing initiation. Blood samples for pharmacokinetics were taken on days 14 through 16. The levels of LDL-C in the GG group were significantly higher than in the AA group at all observation times, with mean differences of 18% to 33% (P < .05). The area under the LDL-C-time curve and the minimum value of LDL-C in the GG group were 24% and 23% higher than in the AA group, respectively (P < .01). There was no significant difference in other lipids, CK, and pharmacokinetic parameters. The HMGCR rs3846662 GG genotype was quantitatively documented to be a significant determinant for higher LDL-C level in basal state and possibly in response to atorvastatin.

Background Phenobarbital (PB), commonly used as the preferred treatment for neonatal seizure, is a drug that requires careful dose adjustments based on therapeutic drug monitoring. It has been reported that PB metabolism was affected by cytochrome P450 (CYP)2C19 polymorphisms in adults requiring dose adjustment. Aim This study aimed to evaluate the effects of CYP2C19 genetic polymorphisms on PB pharmacokinetics (PK) in neonates and infants with seizures. Methods CYP2C19 (wild type: CYP2C19*1/*1, heterozygous extensive metabolisers: CYP2C19*1/*2, *1/*3 and poor metabolisers: CYP2C19*2/*2, *2/*3) genetic polymorphisms in 52 neonates and infants with seizures were analysed. PK parameters were compared based on genotypes. The NONMEM program was used for population PK modelling. Results No significant difference in PB clearance (CL), volume of distribution (Vd) and concentrations were shown among the CYP2C19 genotype groups. The results of PK modelling were as follows: Vd=3590 ×(body weight (BWT)/4) 0.766 ×(AGE/2) 0.283 and CL=32.6×(BWT/4) 1.21 . Conclusions PB PK parameters of neonates and infants with seizures were not significantly different among the groups with different CYP2C19 genotypes. The addition of CYP2C19 genotyping to PK models did not improve the dosing strategies in neonates and infants.

Leptomeningeal carcinomatosis is a devastating complication of malignant disease. In this study, we evaluated the safety and pharmacokinetics of intrathecally administered pemetrexed in rats.Three levels of pemetrexed (0.3, 1, and 3 mg/kg) were administered to 15 rats per level (45 rats in total) twice a week for 2 weeks through specifically designed indwelling subarachnoid catheters. Presence of clinical and pathological neurotoxicity was evaluated. To evaluate the pharmacokinetics of pemetrexed, independent cohorts of 30 rats were treated with 1 mg/kg of pemetrexed and its concentration in cerebrospinal fluid (CSF) and blood was measured using UPLC/MS/MS.There were no cases of clinical or pathologic neurotoxicity after intrathecal administrations of pemetrexed at levels of 0.3 and 1 mg/kg; however, 5 of 15 (33%) rats died after administration of 3 mg/kg pemetrexed. The distribution/elimination of pemetrexed in CSF was best described by a two-compartment model, with initial and terminal half-lives of 0.43 and 1.43 h, respectively. The predicted maximal concentration in CSF was 588 μM, and high levels of pemetrexed appeared to be maintained for a long time. Area under the curve and volume of distribution at steady state were 560 μM h and 1.14 ml, respectively.The no observed adverse effect level of intrathecal administration of pemetrexed was 1 mg/kg in rats. At this level, therapeutically high and durable pemetrexed concentrations could be achieved. Based on these results, further research on intrathecal pemetrexed in humans or non-human primates should be considered.

We investigated genetic polymorphisms in the pregnane X receptor (NR1I2) in Korean individuals (n = 83) and the effects of NR1I2 genotypes on rifampin-mediated induction of bupropion hydroxylation. The pharmacokinetics of bupropion and hydroxybupropion were evaluated after an oral dose of bupropion (150 mg) administered before and after rifampin treatment for 7 days in 35 healthy subjects. The area under the time-concentration curve (AUC) ratio of hydroxybupropion to bupropion in CYP2B6*6 carriers was significantly lower than that in CYP2B6*6 noncarriers in both the basal and rifampin-induced states (p = 0.012). Among the CYP2B6*6 carriers (n = 13), the NR1I2 TGT (-25385T + g.7635G + g.8055T) carriers exhibited a significantly lower AUC ratio, representing the CYP2B6 hydroxylation activity, compared with the TGT noncarriers, in the induced state (11.9 versus 20.3, p = 0.045). The percent difference in the AUC ratio between the basal and induced states was also significantly different (212% versus 58.8%, p = 0.006). However, no significant difference was observed among the NR1I2 TGT genotypes for the CYP2B6*6 noncarriers (n = 22). In conclusion, it is suggested the NR1I2 TGT genotype decreases the bupropion hydroxylation induced by treatment with rifampin, particularly in CYP2B6*6 carriers.

Objective: This study compared the bioavailability and tolerability of a fixed-dose combination (FDC) tablet of glimepiride/metformin 2/500 mg and glimepiride 2-mg + metformin 500-mg tablets administered separately in healthy Korean subjects. Methods: In this single-dose, open-label, 2-period crossover study, healthy Korean volunteers were randomly assigned to receive, in 1 of 2 randomized sequences, an FDC tablet of glimepiride/metformin 2/500 mg (test) and glimepiride 2-mg + metformin 500-mg tablets administered separately (reference), with a 1-week washout period between treatments. Plasma concentrations of glimepiride and metformin were measured using LC/MS-MS. Pharmacokinetic parameters were analyzed using noncompartmental methods. Bioequivalence was concluded if the 90% CIs of the geometric mean test/reference ratios (GMRs) of the logarithm-transformed C max , AUC from 0 to 30 hours (AUC 0–30 ), and AUC 0−∞ values were within the predetermined regulatory range of 80% to 125%. Tolerability was assessed using physical examination and laboratory analysis. Results: A total of 32 subjects were enrolled (16 men [mean (SD) age, 21.8 (2.7) years (range, 18–26 years); weight, 68.9 (8.3) kg (range, 55.5–85.0 kg)]; 16 women [age, 23.5 (4.5) years (range, 20–38 years); weight, 51.7 (3.5) kg (range, 46.8–58.0 kg)]). The GMRs (90% CI) of glimepiride C max , AUC 0–30 , and AUC 0−∞ were 1.01 (0.91–1.11), 0.98 (0.92–1.03), and 0.97 (0.93–1.04), respectively. For metformin, these values were 0.96 (0.87–1.06), 0.96 (0.90–1.03), and 0.96 (0.90–1.03). A total of 49 adverse events (AEs) were reported in 10 subjects (31.3%) with the FDC and in 13 subjects (40.6%) with the separate tablets. The most commonly reported AEs with the test and reference treatments were dizziness (6 [19%] and 7 [22%]) and sweating (4 [13%] and 7 [22%]), respectively. The severity of all of the AEs was considered to be mild, and there were no significant differences in the prevalences of AEs between the 2 formulations. Conclusions: In this study in healthy Korean subjects, the requirements for bioequivalence of the glimepiride/metformin 2/500-mg FDC and coadministration of separate tablets of each drug were met. Both formulations were generally well tolerated.

Tacrolimus is metabolized by CYP3A and has highly variable pharmacokinetics. To study the factors contributing to this high variability in pharmacokinetics and to investigate the possibility of genotype-specific clinical applications, the effect of differing CYP3A5 genotypes on the intrasubject coefficients of variation for tacrolimus was investigated. Genotyping for CYP3A5*3 was performed in healthy volunteers who had previously participated in the pharmacokinetic study of 2 tacrolimus formulations with a 2 x 2 cross-over design. Intrasubject coefficients of variation calculated from analysis of variation in CYP3A5*1/*1+*1/*3 (n = 16) and CYP3A5*3/*3 (n = 13) groups were compared. The intrasubject CVs of AUClast and Cmax in the CYP3A5*3/*3 group were about 41.1% and 52.4% greater than those in the CYP3A5*1*1+*1/*3 group. The estimated total sample size for the bioequivalence study of tacrolimus with a 2 x 2 cross-over design was increased by 93.3% for AUClast (n = 30 versus 58) and 121.4% for Cmax (n = 28 versus 62) in the CYP3A5*3/*3 group compared with the CYP3A5*1/*1+*1/*3 group. The intraindividual variability of tacrolimus PK parameters may be associated with the CYP3A5 genotype. We propose that genotyping for CYP3A5 will provide a more efficient approach for bioequivalence designs and therapeutic drug monitoring.

OBJECTIVE This study aimed to evaluate the effect of genetic polymorphisms of SLCO1B1 and ABCB1 on the pharmacokinetics of atorvastatin and its metabolites. METHODS 290 Koreans were genotyped for SLCO1B1, ABCB1 and CYP3A5, and 28 subjects were selected for the pharmacokinetic study. Each subject received a single oral dose of 20 mg atorvastatin and blood samples were collected up to 48 hr after dosing. The relationship between the genotypes and atorvastatin pharmacokinetics was examined. RESULTS For SLCO1B1 genotypes, the mean area under the concentration-time curve from time 0 to infinity (AUC0-infinity) of atorvastatin was 148.2 ng x hr/ml for *15/*15 subjects (n = 3), which was significantly larger than for 1a/*15 and *1b/*15 (n = 8) (80.7 ng x hr/ml, p = 0.0121) and also larger than for *1a/*1a, *1a/*1b and *1b/*1b (n = 17) (66.3 ng x hr/ml, p = 0.0018). The mean AUC0-infinity of 2-hydroxyatorvastatin for *15/*15 was also larger than in *1a/*1a, *1a/*1b and *1b/*1b (p = 0.012). In lactone forms, no significant pharmacokinetic difference was found among the genotypes. For ABCB1 genotypes, the half-lives of atorvastatin, atorvastatin lactone, 2-hydroxyatorvastatin and 2-hydroxyatorvastatin lactone were significantly longer in c.2677TT-c.3435TT (n = 3) vs. c.2677GG-c.3435CC and c.2677GT-c.3435CT (n = 10), yielding p = 0.049, 0.007, 0.007 and 0.007, respectively. CONCLUSION This study shows that the SLCO1B1*15 allele may be associated with the individual difference in the AUC0-infinity of atorvastatin whereas the ABCB1 TT-TT diplotype may affect the elimination half-life of the drug in the Korean population.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The phosphodiesterase (PDE) type 5 inhibitor is a widely used agent that facilitates penile erection. • Udenafil is newly developed as a PDE-5 inhibitor. WHAT THIS STUDY ADDS • This is the first study to determine the safety, tolerability and pharmacokinetics of udenafil in healthy subjects. • Udenafil was safe and well tolerated in healthy Korean subjects. • The AUC and Cmax of udenafil increased supraproportionally with increasing dose upon single administration, but there was no significant drug accumulation upon multiple administrations. AIM To evaluate the safety, tolerability and pharmacokinetics (PK) of udenafil, a novel phosphodiesterase type 5 inhibitor. METHODS A double-blind, randomized, placebo-controlled, dose-rising, parallel-group, single- and multiple-dose study was conducted in healthy Korean subjects. The subjects were allocated to single-dose groups of 25, 50, 100, 200 or 300 mg (eight subjects in each dose group, including two placebos), or to multiple-dose groups of 100 or 200 mg (once-daily dosing for 7 days; nine subjects in each dose group, including three placebos). Serial samples of blood and urine were collected after oral administration and the drug concentrations in plasma and urine were determined by high-performance liquid chromatography. Safety and tolerability were evaluated by monitoring clinical laboratory parameters and adverse events. RESULTS Udenafil reached peak plasma concentrations at 0.8–1.3 h, and then declined mono-exponentially with a terminal half-life of 7.3–12.1 h in the single-dose study. The area under the time–concentration curves (AUC) and maximum plasma concentrations (Cmax) increased supraproportionally with increasing dose in the single-dose study. During multiple dosing, a steady state was reached at 5 days and little accumulation occurred after repeated dosing for 7 days. Udenafil was generally well tolerated in these healthy subjects, and no serious adverse events occurred. CONCLUSIONS Udenafil was safe and well tolerated in healthy volunteers. The AUC and Cmax of udenafil increased supraproportionally with increasing dose upon single administration, but there was no significant drug accumulation upon multiple administrations.

Background Pitavastatin is a potent, newly developed 3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitor for the treatment of hyperlipidemia. We characterized the effects of organic anion transporting polypeptide 1B1 (OATP1B1) alleles *1a, *1b, and *15 on the pharmacokinetics of pitavastatin. Methods Twenty–four healthy Korean volunteers who had previously participated in a pharmacokinetic study of pitavastatin (single oral dose, 1–8 mg) were further investigated. Subjects were grouped according to OATP1B1 genotype. Dose–normalized area under the plasma concentration–time curve (AUC) and peak plasma concentration (Cmax) values were analyzed, because different dosages were administered to subjects, whereas the pharmacokinetics showed linear characteristics. Results Dose-normalized pitavastatin AUCs for *1b/*1b (group 1), *1a/*1a or *1a/*1b (group 2), and *1a/*15 or *1b/*15 (group 3) were 38.8 ± 13.3, 54.4 ± 12.4, and 68.1 ± 16.3 ng · h · mL−1 · mg−1 (mean ± SD), respectively, with significant differences between all 3 groups (P = .008) and between subjects carrying and those not carrying the *15 allele (P = .004). Dose-normalized pitavastatin Cmax values were 13.2 ± 3.3, 18.2 ± 5.7, and 29.4 ± 9.6 ng · mL−1 · mg−1 in groups 1, 2, and 3, respectively, and also showed significant differences (P = .003) in a manner similar to that shown by AUC. No significant differences were found between the genotype groups in terms of dose-normalized AUC or Cmax values of pitavastatin lactone. Conclusion OATP1B1 variant haplotypes were found to have a significant effect on the pharmacokinetics of pitavastatin. These results suggest that the *15 allele is associated with decreased pitavastatin uptake from blood into hepatocytes and that OATP1B1 genetic polymorphisms have no effect on the pharmacokinetics of pitavastatin lactone. Clinical Pharmacology & Therapeutics (2005) 78, 342–350; doi: 10.1016/j.clpt.2005.07.003

Objective Our objective was to investigate the effect of the uridine 5′-diphosphate-glucuronosyltransferase (UGT) 2B15 genetic polymorphism on the pharmacokinetics and pharmacodynamics of lorazepam in basal, inhibited, and induced metabolic states in healthy normal volunteers. Methods Twenty-four healthy subjects were enrolled and grouped into UGT2B15*1/*1 or UGT2B15*2/*2 genotype groups. The pharmacokinetic and pharmacodynamic profiles of intravenous lorazepam were characterized before and after inhibition with 600 mg valproate once daily for 4 days and after induction with rifampin (INN, rifampicin) pretreatment (600 mg once daily for 10 days), with a washout period of 10 days between. The plasma concentrations of lorazepam and lorazepam glucuronide were analyzed before and at 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 hours after lorazepam administration by liquid chromatography-tandem mass spectrometry. Visual analog scale assessments and psychomotor coordination tests were administered before and up to 12 hours after drug administration. Results The UGT2B15*2/*2 group showed 0.58-fold (95% confidence interval, 0.43–0.72; P

Background and Objectives There have been considerable disagreements regarding the influence of MDR1 (ABCB1) polymorphisms on the disposition of P-glycoprotein (P-gp) substrates. We speculated that the unknown function of the A allele of exon 21 G2677T/A (Ala893Ser/Thr) provides one of the reasons for the contradictory results. This study was performed to clarify the effects of major MDR1 gene polymorphisms, including a variant A allele in exon 21, on fexofenadine pharmacokinetics. Methods We investigated the occurrence of 3 high-frequency single-nucleotide polymorphisms (SNPs) in exons 12 (C1236T), 21 (G2677T/A), and 26 (C3435T) of the MDR1 gene in 232 healthy Koreans, using a polymerase chain reaction-restriction fragment length polymorphism method, and performed haplotype analysis on these 3 SNPs. A single oral dose of 180 mg fexofenadine hydrochloride was administered to 33 healthy Korean male volunteers, who were divided into 6 groups based on the MDR1 genotype for the G2677T/A polymorphism in exon 21 and the C3435T polymorphism in exon 26. Results A strong linkage disequilibrium was observed among the 3 SNPs. The frequencies of the 4 major haplotypes, 1236C-2677A-3435C, C-G-C, T-G-C, and T-T-T, were 16.4%, 18.6%, 21.6%, and 32.2%, respectively. Fexofenadine disposition varied considerably among the groups. In the 2677AA/3435CC genotype group (n = 3), the values of area under the concentration-time curve from time 0 to 24 hours [AUC(0–24)] were significantly lower (P = .014) than those of the other 5 genotype groups (GG/CC, GT/CT, TT/TT, GA/CC, and TA/CT). As compared with the 2677GG/3435CC subjects, the AUC(0–24) values were 17% lower in the 2677AA/3435CC subjects and 47% higher in the 2677TT/3435TT subjects (GG/CC versus AA/CC versus TT/TT, 4017 ± 1137 ng · h/mL versus 3315 ± 958 ng · h/mL versus 5934 ± 2,064 ng · h/mL; P = .018). By stratification for genotypes at position 3435, homozygous 3435TT subjects were found to have significantly higher AUC(0–24) (P = .024) and maximum plasma concentration (P = .040) values than CC subjects [AUC(0–24), 5934 ± 2064 ng · h/mL versus 3998 ± 1241 ng · h/mL; maximum plasma concentration, 958 ± 408 ng/mL versus 673 ± 242 ng/mL]. Conclusions The plasma concentrations of fexofenadine after a single oral administration were lower in 2677AA/3435CC subjects than in subjects with the other 5 genotype combinations of the SNPs of G2677T/A and C3435T. These findings confirm the importance of analyzing MDR1 haplotypes and provide a plausible explanation for the conflicting results regarding the effect of MDR1 polymorphisms on the disposition of P-gp substrates. Clinical Pharmacology & Therapeutics (2004) 76, 418–427; doi: 10.1016/j.clpt.2004.08.002

Objective Our objective was to investigate the effect of the CYP3A5 genotype on the systemic clearance of midazolam in constitutive, inhibited, and induced metabolic conditions. Methods Nineteen healthy volunteers were grouped with regard to the CYP3A5*3 allele, into homozygous wild-type (CYP3A5*1/*1, n = 6), heterozygous (CYP3A5*1/*3, n = 6), and homozygous variant-type (CYP3A5*3/*3, n = 7) subject groups. The pharmacokinetic profile of intravenous midazolam was characterized before and after itraconazole administration (200 mg once daily for 4 days) and also after rifampin (INN, rifampicin) pretreatment (600 mg once daily for 10 days), with a washout period of 2 weeks in between. Results The pharmacokinetic profiles of midazolam and of its hydroxy metabolites did not show differences between the genotype groups under basal and induced metabolic conditions. However, during the inhibited metabolic state, the CYP3A5*3/*3 group showed a greater decrease in systemic clearance than was seen in the CYP3A5*1/*1 group (8.5 ± 3.8 L · h−1 · 70 kg−1 versus 13.5 ± 2.7 L · h−1 · 70 kg−1, P = .027). The 1′-hydroxymidazolam–to–midazolam area under the plasma concentration–time curve ratio was also significantly lower in the CYP3A5*3/*3 group (0.58 ± 0.35 versus 1.09 ± 0.37 for the homozygous wild-type group, P = .026). Conclusions The CYP3A5 genotype did not affect the pharmacokinetics of intravenous midazolam in the basal or induced states. However, during cytochrome P450 (CYP) 3A inhibition by itraconazole, individuals carrying the CYP3A5*1 allele were found to be less susceptible to changes in systemic clearance and showed higher 1′-hydroxymidazolam–to–midazolam area under the plasma concentration–time curve ratios, probably resulting from the relatively CYP3A4-specific inhibition caused by itraconazole. Clinical Pharmacology & Therapeutics (2004) 76, 104–112; doi: 10.1016/j.clpt.2004.03.009

Purpose: The rationale for developing an alternative paclitaxel formulation concerns Cremophor EL-related side effects, and a novel paclitaxel delivery system might augment its therapeutic efficacy. Genexol-PM is a polymeric micelle formulated paclitaxel free of Cremophor EL. A phase I study was performed to determine the maximum tolerated dosage, dose-limiting toxicities, and the pharmacokinetic profile of Genexol-PM in patients with advanced, refractory malignancies. Experimental Design: Twenty-one patients were entered into the study. Genexol-PM was i.v. administered over 3 h every 3 weeks without premedication. The Genexol-PM dose was escalated from 135 mg/m2 to 390 mg/m2. Results: All of the patients were evaluable for toxicity and response. Acute hypersensitivity reactions were not observed. Neuropathy and myalgia were the most common toxicities. During cycle 1, grade 3 myalgia occurred in 1 patient at 230 and 300 mg/m2, respectively. At 390 mg/m2, 2 of 3 patients developed grade 4 neutropenia or grade 3 polyneuropathy. Therefore, the maximum tolerated dosage was determined to be 390 mg/m2. There were 3 partial responses (14%) among the 21 patients. Of the 3 responders, 2 were refractory to prior taxane therapy. The paclitaxel area under the curve from time 0 to infinity and peak or maximum paclitaxel concentration seemed to increase with escalating dose, except at 230 mg/m2, which suggests that Genexol-PM has linear pharmacokinetics. Conclusion: The main dose-limiting toxicities were neuropathy, myalgia, and neutropenia, and the recommended dosage for a phase II study is 300 mg/m2. Genexol-PM is believed to be superior to conventional paclitaxel in terms of the obviation of premedication and the delivery of higher paclitaxel doses without additional toxicity.

To evaluate the effect of the CYP2D6 genotype on the pharmacokinetics of tropisetron in healthy Korean subjects. A single 5-mg capsule of tropisetron was administered orally to 13 healthy subjects. Plasma concentrations were determined by validated HPLC procedures and data were analyzed by using noncompartmental linear PK methods. Four alleles, CYP2D6*1, CYP2D6*2 ×2, CYP2D6*5, and CYP2D6*10, were identified by PCR. Thirteen subjects, consisting of two homozygous carriers of the wild type allele (*1/*1), four heterozygous carriers of poor metabolizer (PM)-associated allele (*1/*10), six homozygous carriers of PM-associated alleles (four with *10/*10 and two with *5/*10), and one carrier of a duplicated allele *1/*2 ×2. All tested pharmacokinetic parameters (AUCinf, AUCinf NL70, Cmax, CmaxNL70, T1/2, and Tec) were significantly different among four different genotypic groups. The mean AUCs of carriers with the heterozygous PM-associated allele and the homozygous PM-associated allele were 1.9- and 6.8-higher than those of carriers with the wild type allele, respectively. In contrast, the mean AUC of carriers with a duplicated allele was 0.5-fold lower than that of those carriers with the wild type allele. The presence of CYP2D6*5, CYP2D6*10, and CYP2D6*2 ×2 has an important impact on the pharmacokinetics of tropisetron, which may influence clinical response to tropisetron therapy.

Background The aim of this study was to explore the pharmacokinetic-pharmacodynamic (PK-PD) relationship of metformin on glucose levels after the administration of 250 mg and 1000 mg of metformin in healthy volunteers. Methods A total of 20 healthy male volunteers were randomized to receive two doses of either a low dose (375 mg followed by 250 mg) or a high dose (1000 mg followed by 1000 mg) of metformin at 12-h intervals. The pharmacodynamics of metformin was assessed using oral glucose tolerance tests before and after metformin administration. The PK parameters after the second dose were evaluated through noncompartmental analyses. Four single nucleotide polymorphisms in MATE1, MATE2-K, and OCT2 were genotyped, and their effects on PK characteristics were additionally evaluated. Results The plasma exposure of metformin increased as the metformin dose increased. The mean values for the area under the concentration-time curve from dosing to 12 hours post-dose (AUC0-12h) were 3160.4 and 8808.2 h·μg/L for the low- and high-dose groups, respectively. Non-linear relationships were found between the glucose-lowering effect and PK parameters with a significant inverse trend at high metformin exposure. The PK parameters were comparable among subjects with the genetic polymorphisms. Conclusions This study showed a non-linear PK-PD relationship on plasma glucose levels after the administration of metformin. The inverse relationship between systemic exposure and the glucose-lowering effect at a high exposure indicates a possible role for the intestines as an action site for metformin. Trial registration ClinicalTrials.gov NCT02712619.