Yook-Hwan Noh

Effects of Ketoconazole and Rifampicin on the Pharmacokinetics of Gemigliptin, a Dipeptidyl Peptidase-IV Inhibitor: A Crossover Drug-Drug Interaction Study in Healthy Male Korean Volunteers

BACKGROUND Gemigliptin (LC15-0444) is a newly developed selective and competitive inhibitor of dipeptidyl peptidase (DPP)-4 and has potential for the treatment of type 2 diabetes mellitus. Gemigliptin is metabolized by the cytochrome P450 (CYP) 3A4 isozyme to yield the active major metabolite LC15-0636. OBJECTIVE The effects of multiple oral doses of ketoconazole (a potent CYP3A4 inhibitor) and multiple oral doses of rifampicin (a potent CYP3A4 inducer) on the pharmacokinetic properties of a single oral dose of gemigliptin were evaluated in fasting healthy male Korean volunteers. METHODS In this open-label, 2-part, 3-treatment, 1-sequence, 2-period crossover drug-drug interaction study, 1 group of subjects received a single 50-mg oral dose of gemigliptin on 2 separate occasions-once as monotherapy and again after pretreatment with 400 mg of oral ketoconazole once daily for 7 days. The other group of subjects received a single 50-mg oral dose of gemigliptin on 2 separate occasions-once without pretreatment and again after pretreatment with 600 mg of oral rifampicin once daily for 10 days. Blood samples were obtained at 0 (predose), 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, 24, 48, and 72 hours after gemigliptin dosing. Plasma concentrations were determined using LC-MS/MS. Pharmacokinetic parameters were estimated via noncompartmental methods. Tolerability was assessed using measurements of vital signs, clinical chemistry tests, and interviews. RESULTS Twenty-four subjects were enrolled (12 per group). Concurrent administration of ketoconazole was associated with increased total gemigliptin plasma exposure (AUC(0-∞); 2.36-fold [90% CI, 2.19-2.54]) and decreased metabolism of gemigliptin until negligible concentrations of LC15-0636 were detected. Pretreatment with rifampicin was associated with decreased AUC(0-∞) of gemigliptin (by 80% [90% CI, 78%-82%]) and a 2.9-fold increase (mean [SD], 0.18 [0.08] to 0.52 [0.10]) in the metabolic ratio of gemigliptin to LC15-0636. The treatments were well-tolerated, with no severe adverse events reported. Six of the 24 subjects (25%) experienced AEs during the first period of gemigliptin monotherapy administration. Six of 12 subjects (50%) each experienced AEs during concurrent administration with ketoconazole and rifampicin. CONCLUSIONS In this select group of healthy male Korean volunteers, concurrent administration of gemigliptin with ketoconazole or rifampicin was associated with significantly increased or decreased systemic exposure to gemigliptin, respectively. These findings suggest that gemigliptin may require a dose adjustment when concurrently administered with drugs that alter CYP3A4 activity. Concurrent administration of gemigliptin with ketoconazole or rifampicin was well tolerated. ClinicalTrials.gov identifier: NCT01426906.

Pharmacokinetic Interaction Between Pitavastatin and Valsartan: A Randomized, Open-Labeled Crossover Study in Healthy Male Korean Volunteers

BACKGROUND Pitavastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, and valsartan, an angiotensin receptor blocker, are used concurrently in some patients who are both hyperlipidemic and hypertensive. However, to date, no published studies have explored whether there is an interaction between pitavastatin and valsartan. OBJECTIVE The aim of this study was to investigate the potential pharmacokinetic interaction between pitavastatin and valsartan in healthy male volunteers in Korea. METHODS A randomized, open-label crossover study was conducted in healthy male Korean volunteers. In varying sequences, each subject received pitavastatin 2 × 2 mg, valsartan 2 × 160 mg, and both treatments, once daily for 7 consecutive days, with a 7-day washout period between each treatment period. Plasma samples were obtained at steady state for the pharmacokinetic evaluation of pitavastatin and valsartan. Pharmacodynamic assessment included lipid profiles and vital sign measurements (systolic and diastolic blood pressure [SBP and DBP, respectively] and pulse rate [PR]). A safety profile assessment, which included vital sign measurements, ECG, and clinical laboratory testing, was performed in each subject. RESULTS A total of 24 subjects were enrolled (mean age, 30.5 years [range, 23.0-45.0 years]; mean body weight, 71.2 kg [range, 56.1-86.0 kg]; and mean body mass index, 23.2 kg/m(2) [range, 19.2-25.8 kg/m(2)]). The 95% CIs of the geometric mean ratios of AUC(τ) and C(max,ss) of pitavastatin were 0.97 to 1.11 and 0.73 to 1.09, respectively. The 95% CIs of the geometric mean ratios of AUC(τ) and C(max,ss) of valsartan were 0.90 to 1.27 and 0.81 to 1.29. Pitavastatin administered as monotherapy and in combination with valsartan was associated with significantly lowered total cholesterol and LDL-C compared with valsartan monotherapy (both, P < 0.05). Differences in lipid-lowering effects were not statistically significant between pitavastatin monotherapy and pitavastatin combined with valsartan. Valsartan monotherapy and valsartan combined with pitavastatin were associated with significantly lower SBP and DBP compared with baseline (both, P < 0.05), although no significant changes in PR were observed. No significant differences in BP or PR changes were noted between concurrent administration of valsartan monotherapy compared with pitavastatin + valsartan. There were no serious AEs reported, and none of the subjects discontinued the study due to AEs. CONCLUSIONS The pharmacokinetic profiles of pitavastatin and valsartan administered as monotherapy were comparable to combination treatment in these healthy male Korean volunteers, suggesting that individual pharmacokinetic properties are not significantly affected by concurrent administration. The concurrent administration of pitavastatin and valsartan was generally well tolerated. The findings from the present study provide a basis for a larger study in hypertensive patients with hyperlipidemia.

Evaluation of Pharmacokinetic and Pharmacodynamic Profiles and Tolerability After Single (2.5, 5, or 10 mg) and Repeated (2.5, 5, or 10 mg BID for 4.5 days) Oral Administration of Ivabradine in Healthy Male Korean Volunteers

BACKGROUND Ivabradine, a selective inhibitor of the pacemaker current in the sinoatrial node, has shown pure heart rate (HR)-reducing effects with anti-ischemic efficacy as well as improvement in heart failure outcomes. OBJECTIVE The purpose of this study was to explore pharmacokinetic (PK) and pharmacodynamic (PD) characteristics and tolerability in healthy male Korean volunteers, as well as to compare them with PK/PD profiles of white subjects. METHODS This was a randomized, double-blind, placebo-controlled Phase I study conducted in healthy male subjects. For each of the 3 dosing groups, 9 subjects were randomized to receive ivabradine and 3 to receive placebo. Subjects received a single oral dose of ivabradine 2.5, 5, or 10 mg and after a 3-day washout period, repeat doses of 2.5, 5, or 10 mg BID for 4.5 days. Blood and urine samples were collected over 72 hours during each period, and levels of ivabradine and its metabolite S18982 were determined by using validated LC-MS/MS, followed by noncompartmental PK analysis. For PD properties and tolerability, 24-hour Holter recordings were obtained: at baseline, after a single dose, after repeated doses, and after the last dose. Serial resting 12-lead ECG assessments were also performed throughout the study. RESULTS Forty-eight subjects were enrolled, and 45 completed the study. After single doses of 2.5, 5, and 10 mg, respective mean Cmax levels of ivabradine were 9, 15, and 39 ng/mL, and mean AUC0-last values were 30, 52, and 121 ng h/mL. At steady state, mean Cmax,ss levels were 11, 19, and 42 ng/mL, reached at a median Tmax of 0.67 hour for all 3 doses. The mean AUC0-τ levels were 43, 58, and 139 ng h/mL, respectively. The PK findings were linear with dose and time. Decreases in mean HR on both the Holter recordings and ECGs were observed in all of the ivabradine groups compared with placebo. After the repeated doses, mean decreases in HR were greater than those for the single doses for the same period. Statistically significant differences were observed between the 5- and 10-mg ivabradine groups and placebo. A total of 3 adverse events were reported in 2 subjects receiving ivabradine; both fully recovered without sequelae. CONCLUSIONS Single and repeated administration of ivabradine were generally well tolerated in these healthy male Korean volunteers. Ivabradine induced significant reductions in HR, especially at doses of 5 and 10 mg. PK/PD characteristics were similar to those found in white subjects, suggesting that the dose concentration-response relationship of ivabradine is similar between Korean and white subjects.

The pharmacokinetics of letrozole: association with key body mass metrics

PURPOSE To characterize the pharmacokinetics (PK) of letrozole by noncompartmental and mixed effect modeling analysis with the exploration of effect of body compositions on the PK. METHODS The PK data of 52 normal healthy male subjects with intensive PK sampling from two separate studies were included in this analysis. Subjects were given a single oral administration of 2.5 mg letrozole (Femara®), an antiestrogenic aromatase inhibitor used to treat breast cancer. Letrozole concentrations were measured using validated high-performance liquid chromatography with tandem mass spectrometry. PK analysis was performed using NONMEM® 7.2 with first-order conditional estimation with interaction method. The association of body composition (body mass index, soft lean mass, fat free mass, body fat mass), CYP2A6 genotype (*1/*1, *1/*4), and CYP3A5 genotype (*1/*1, *1/*3, *3/*3) with the PK of letrozole were tested. RESULTS A two-compartment model with mixed first and zero order absorption and first order elimination best described the letrozole concentration-time profile. Body weight and body fat mass were significant covariates for central volume of distribution and peripheral volume of distribution (Vp), respectively. In another model built using more readily available body composition measures, body mass index was also a significant covariate of Vp. However, no significant association was shown between CYP2A6 and CYP3A5 genetic polymorphism and the PK of letrozole in this study. CONCLUSION Our results indicate that body weight, body fat mass, body mass index are associated with the volume of distribution of letrozole. This study provides an initial step toward the development of individualized letrozole therapy based on body composition.

Bioavailability and tolerability of combination treatment with revaprazan 200 mg + itopride 150 mg: a randomized crossover study in healthy male Korean volunteers.

BACKGROUND To date, no definitive treatment of functional dyspepsia (FD) has been proven to be effective and reasonably well-tolerated. Proton pump inhibitors (PPIs) combined with prokinetic agents are considered an effective option. Revaprazan is a selective potassium-competitive acid blocker that reversibly inhibits gastric H(+)/K(+)-ATPase and shows effective acid suppression comparable to PPIs. Itopride is a prokinetic agent that has anticholinesterase activity as well as dopamine D(2) receptor antagonistic activity. For this reason, revaprazan and itopride have been prescribed for FD; however, no available studies have reported the pharmacokinetic interactions of these 2 drugs. OBJECTIVE The objective of this study was to compare the bioavailability and tolerability of revaprazan and itopride combination therapy to those of equally dosed monotherapies to acquire basic drug-drug interaction information about revaprazan. METHODS This multiple-dose, randomized crossover study was conducted in healthy male Korean subjects. Subjects received, in randomized sequence, a 7-day oral dose of revaprazan 200 mg once daily, itopride 50 mg TID, or both. Each treatment period was separated by a 7-day washout period. Blood samples were collected for up to 24 hours following the last dose at steady state, and drug concentrations were determined using validated LC/MS-MS. Pharmacokinetic properties were obtained using noncompartmental analysis. Drug tolerability was assessed throughout the study, using measurements of vital signs, clinical chemistry testing, and interviews. RESULTS A total of 30 subjects were enrolled in the study. Among them, 28 subjects completed revaprazan treatment, and 27 completed the study (3 subjects were withdrawn). The geometric mean ratios (GMRs) (90% CI) of C(max,ss), and AUC(τ,ss) with revaprazan were 0.92 (0.84-1.00) and 0.96 (0.89-1.03), respectively. The GMRs of C(max,ss) and AUC(τ,ss) with itopride were 1.07 (0.96-1.20) and 1.12 (1.06-1.18), respectively. A total of 15 adverse events (AEs) were reported in 8 subjects. All AEs were considered to be mild, and there were no clinically significant differences between treatment groups. CONCLUSION The findings from this study suggest bioequivalence between revaprazan given as monotherapy and in combination with itopride in these healthy Korean male volunteers, with no clinical significant drug-drug interaction. All treatments in this study was generally well tolerated. ClinicalTrials.gov identifier: NCT0133289.

Pharmacokinetic Interaction of Telmisartan With S-Amlodipine: An Open-Label, Two-Period Crossover Study in Healthy Korean Male Volunteers

BACKGROUND Telmisartan belongs to a class of orally active angiotensin II receptor blockers (ARBs), and S-amlodipine is an enantiomer of amlodipine. Amlodipine is a racemic mixture and the calcium channel blocking (CCB) effect is confined to S-amlodipine, whereas R-amlodipine has a 1000-fold lower activity and no racemization occurs in vivo in human plasma. Combination therapy of ARBs with CCBs provides advantages for blood pressure control and vascular protection over monotherapy. OBJECTIVE To investigate the effects of coadministration of telmisartan and S-amlodipine on the steady-state pharmacokinetic properties of each drug as a drug-drug interaction study required before developing the fixed-dose combination agent. METHODS This study comprised 2 separate parts, A and B; each was a multiple-dose, open-label, 2-sequence, 2-period, crossover study in healthy male Korean volunteers. In part A, volunteers were administered 80 mg of telmisartan, either alone or with 5 mg of S-amlodipine. In part B, volunteers were administered 5 mg of S-amlodipine, either alone or with 80 mg of telmisartan. Blood samples were taken on days 9 and 37, following the final dose of each treatment, and at 0 (predose), 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, and 24 hours after administration in part A, and were taken at 0 (predose), 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, and 24 hours after administration in part B. Plasma concentrations were determined using LC-MS/MS. The pharmacokinetic properties of each drug after coadministration of telmisartan and S-amlodipine were compared with those of each drug administered alone. Tolerability was assessed using measurements of vital signs, clinical chemistry tests, and interviews. RESULTS Fifty-six volunteers were enrolled (32 in part A and 24 in part B), and all completed except 4 volunteers (3 withdrawn in part A and 1 withdrawn in part B). The geometric mean ratios (GMRs) (90% CI) for the C(max,ss) and AUC(τ,ss) of telmisartan (with or without S-amlodipine) were 1.039 (0.881-1.226) and 1.003 (0.926-1.087), respectively. The GMRs (90% CI) for C(max,ss) and AUC(τ,ss) of S-amlodipine (with or without telmisartan) were 0.973 (0.880-1.076) and 0.987 (0.897-1.085). Total 11 adverse events (AEs) were reported in 7 volunteers (21.9%) in part A. A total of 9 AEs were reported in 6 volunteers (25.0%) in part B. Statistical analysis confirmed that the 90% CIs for these pharmacokinetic parameters were within the commonly accepted bioequivalence range of 0.8 to 1.25, indicating that the extent of bioavailability of S-amlodipine was not affected by telmisartan. The intensity of all AEs was considered to be mild, and there were no significant differences in the prevalences of AEs between the 2 formulations. CONCLUSIONS Following multiple-dose coadministration of high doses of telmisartan and S-amlodipine, the steady-state pharmacokinetic properties of telmisartan were not significantly affected, and telmisartan had no significant effect on the pharmacokinetic properties of S-amlodipine at steady state in these selected groups of healthy volunteers. Both formulations were generally well-tolerated.

Pharmacokinetic Comparison of 2 Formulations of Anastrozole (1 mg) in Healthy Korean Male Volunteers: A Randomized, Single-Dose, 2-Period, 2-Sequence, Crossover Study

BACKGROUND Anastrozole is an aromatase inhibitor used to treat advanced breast cancer in postmenopausal women. A generic 1-mg tablet of anastrozole was recently developed. OBJECTIVE The study was designed to provide data to submit to Korean regulatory authorities to allow marketing of the test formulation. We evaluated the comparative bioavailability and tolerability of the test and reference formulations in healthy male adult volunteers. METHODS This single-dose, randomized, double-blind, 2-way crossover trial was conducted in the Clinical Trial Center at the Asan Medical Center (Seoul, Korea). A total of 24 healthy male Korean volunteers were enrolled. Subjects were randomized to receive 1 mg of the test or reference formulation, and pharmacokinetic (PK) parameters were measured. After a 3-week washout period, the other formulation was administered, and PK parameters were measured again. C(max) and AUC(last) were determined from blood samples obtained at 0.33, 0.67, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 48, 72, 96, 120, 168, and 216 hours after drug administration. The formulations were considered bioequivalent if the 90% CIs of the geometric mean ratios of test-to-reference formulations for AUC(last) and C(max) were within the bioequivalence limits of 0.8 to 1.25. Nonlinear mixed-effect modeling and Monte Carlo simulations for both formulations were also conducted, and the results were used to characterize and compare the PK properties. Safety profile and tolerability were assessed using measurements of vital signs, clinical chemistry tests, and interviews. RESULTS All enrolled subjects completed the study. A total of 8 adverse events (AEs) were reported (2 on test formulation, 6 on reference formulation) in 7 of 24 participants. These AEs were headache (n = 1), hordeolum (n = 1), and abnormal laboratory test values (n = 6). Both formulations were well tolerated, and there were no serious AEs. Both formulations were best described by a 2-compartment disposition model with lag phase. The 90% CIs of the geometric mean ratios of test formulation to reference formulation were 0.96 to 1.08 for C(max) and 0.93 to 1.0 for AUC(last). CONCLUSION The test and reference formulations had similar PK parameters and similar plasma concentration-time profiles. The test formulation of anastrozole met the Korean regulatory criteria (AUC and C(max)) for assuming bioequivalence. ClinicalTrials.gov identifier: NCT01105299.

Effects of food on the pharmacokinetics of gemigliptin/metformin sustained-release 50/1,000 mg (25/500 mg x 2 tablets) fixeddose combination tablet in healthy male volunteers.

OBJECTIVES For patient convenience, a gemigliptin/metformin sustainedrelease fixed-dose combination (FDC) tablet was developed. This study was conducted to investigate the effects of food on the pharmacokinetic (PK) profile of the FDC tablets. MATERIALS AND METHODS This was an open-label, randomized, single dose, 2-period, 2-sequence crossover study in 24 healthy male volunteers. The FDC tablets (25/500 mg × 2 tablets) were administered in high-fat fed and fasted states on separate occasions, and each subject was randomly allocated to each sequence with a 7-day washout period. PK blood samplings were conducted from predose to 48 hours after dosing. Tolerability assessments were performed throughout the study. RESULTS Nine adverse events (AEs) of mild intensity were reported from 8 subjects after study drug administration, and the AE frequency was similar between treatments. No serious AEs were reported. The PK parameters of gemigliptin and metformin were compared between fasting and fed states. For gemigliptin, the geometric mean ratios (GMRs) (fed : fasted state) of the Cmax and AUClast were 0.886 (90% confidence interval (CI) 0.781 - 1.006) and 1.021 (90% CI 0.949 - 1.099), respectively. For metformin, the GMRs of the Cmax and AUClast were 0.811 (90% CI 0.712 - 0.923) and 1.144 (90% CI 1.013 - 1.291), respectively. A prolonged tmax for metformin was observed. These results are similar to the effects of food on each component. CONCLUSION The FDC tablet may have a similar PK profile as that of individual drugs and is generally tolerable when administered with food. These results indicate that the FDC tablet can be administered in the same dosing regimen as each component, especially that of metformin sustained-release.

Effects of Ketoconazole on the Pharmacokinetic Properties of CG100649, A Novel NSAID: A Randomized, Open-Label Crossover Study in Healthy Korean Male Volunteers

BACKGROUND CG100649, a novel selective cyclooxygenase-2 inhibitor that also inhibits carbonic anhydrase I/II, is expected to reduce the cardiovascular risk typical of other NSAIDs. Concurrent medications may influence the activities of the cytochrome P450 (CYP) 3A enzyme through which CG100649 is metabolized. OBJECTIVES This study was designed to evaluate the influence of ketoconazole, a known strong inhibitor of CYP3A, on the pharmacokinetic properties of CG100649. METHODS This randomized, open-label, 2 × 2 crossover study was conducted in healthy Korean male volunteers. Each subject received the following 2 treatments in a randomly allocated sequence, separated by a washout period of 42 days: single oral dose of CG100649 6 mg, and concurrent dosing of CG100649 6 mg and ketoconazole 400 mg followed by ketoconazole 400 mg/d over 4 days. Blood samples for pharmacokinetic analysis were collected at 0 (predose), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72, 96, 120, 144, 240, 384, and 480 hours after dosing of CG100649 in each sequence. Tolerability assessments were performed throughout the study. RESULTS Thirty subjects participated, and 26 subjects completed the study. Seventeen adverse events (AEs) were reported in 10 subjects, and all AEs were recovered without any sequelae. No serious AEs were reported. Six subjects receiving the single dose of CG100649 had 9 AEs, and 7 subjects receiving the combination of ketoconazole and CG100649 had 8 AEs. The Cmax of CG100649 with CG100649 only and with concurrent administration of CG100649 + ketoconazole were similar (10.7 and 11.0 ng/mL, respectively). The CG100649 AUClast with concurrent ketoconazole was 1.29-fold greater than that with CG100649 only (2074.0 and 2685.8 ng · h/mL) and demonstrated a statistically significant difference (P < 0.05). However, there were no statistically significant differences in vital signs, clinical laboratory test results, ECGs, or AEs between treatments. CONCLUSION Although the AUC of CG100649 increased by 29% with the concurrent medication of ketoconazole, it is considered that concurrent administration of CG100649 with ketoconazole would not change the safety profile of CG100649.

Predicting the efficacy of an oral paclitaxel formulation (DHP107) through modeling and simulation.

PURPOSE DHP107 is an oral paclitaxel under development. The present study characterized the pharmacokinetic properties of DHP107 and predicted the efficacy in comparison to that of intravenous paclitaxel, using modeling and simulation of data from the early phase of clinical development. METHODS In the first-in-human study of the pharmacokinetic characteristics of DHP107 and intravenous paclitaxel, patients received DHP107 60 to 600 mg/m(2), followed by intravenous paclitaxel 175 mg/m(2). Using the pharmacokinetic model of DHP107 from the present analysis and from a previously published pharmacodynamic analysis of the association between paclitaxel concentration and neutropenia, phase I clinical trial for DHP107, with a modified Fibonacci dose escalation scheme, were simulated to predict the maximal tolerated dose (MTD). Additional simulations of paclitaxel concentration over time were conducted to compare the efficacy of DHP107 with that of intravenous paclitaxel, based on time over minimum effective concentration. FINDINGS In the clinical trial simulation, 480 mg/m(2) was the most frequently predicted MTD of DHP107. In the simulations for efficacy, the times over minimum effective concentration with DHP107 at the predicted MTD were greater than those of intravenous paclitaxel in weekly regimens. IMPLICATIONS The findings from this analysis suggest the possibility of efficacy of DHP107 in weekly regimens and provides a scientific rationale for further development. Based on findings from modeling and simulation, DHP107 was predicted to be more efficacious compared with intravenous paclitaxel in weekly regimens, and this finding should be confirmed in further clinical trials.