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Various studies have highlighted the importance of ethnic differences. The consideration of ethnic differences in the field of individualized pharmacotherapy is imperative. Therefore, various organizations and networks across countries should aim to conduct multicountry and multiregional clinical trials (MRCTs). If there is solid evidence available to evaluate the existence of ethnic differences between the same regional areas, it will lead to an increase in the efficiency of drug development. The purpose of this paper was to compare the approval dosing regimen among four Asian countries (Korea, Japan, China, and Taiwan) and elucidate the readiness and current status of the implementation of the International Conference on Harmonization (ICH) E17 guidelines on MRCTs. Reducing unnecessary clinical trials via multinational clinical trials in East Asian countries is also suggested. The approved dosing regimens for some drugs in the four Asian countries were similar; however, some differences might be caused by differences in legislation, even though there were no ethnic differences. This indicates that there are several roles to be expected of the Asia Clinical Pharmacology study network for exploratory MRCTs, which would lead to the accumulation of evidence for MRCTs, ultimately accelerating the efficiency of drug development in East Asian countries. The exposure of the new treatment to the necessary patients through collaborative research coordination and simultaneous multinational subject recruitment would serve its role in providing East Asia with specific personalized medicine with a high treatment success rate.

GLH8NDE, a derivative of eupatilin, is currently under development to treat dry eye disease. We conducted a randomized, double‐masked, placebo‐controlled, single‐ and multiple‐day study to evaluate safety, tolerability, pharmacodynamics, and pharmacokinetics of ocular GLH8NDE in healthy male adults. Subjects randomly received topical ocular dosing of GLH8NDE or its matching placebo for a day, then for 7 consecutive days with a 62‐h washout at one of the following daily doses: 9, 18, 36 (Koreans), and 36 mg (Whites). The study drug was administered in divided doses over 10 h with 2‐ or 5‐h intervals. Thirty‐nine (97.5%) out of 40 subjects completed the study. A total of 17 subjects experienced 31 treatment‐emergent adverse events, all of which were mild in severity and recovered without sequelae. Neither pathological changes in eye compartments nor clinically significant systemic effects were observed. GLH8NDE was rapidly absorbed reaching the peak concentration within 0.25–0.75 h postdose. The systemic exposure as measured by area under the concentration‐time curve from time of administration up to the time of the last quantifiable concentration (AUClast) after single‐day administration of the same dose was 109% higher in Koreans than in Whites. In conclusion, GLH8NDE was safe and well‐tolerated in healthy Korean and White male adults at 9–36 mg/day after single‐ and multiple‐day administrations.

Amikacin is used as a therapy for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) who are resistant to macrolide antibiotics or have severe symptoms. This study aimed to characterize the pharmacokinetic properties of amikacin in patients with NTM-PD by developing a population pharmacokinetic model and to explore the optimal pharmacotherapy in patients with NTM-PD. For this study, all data were retrospectively collected. The amikacin pharmacokinetic properties were best described by a two-compartment model with first-order elimination. The estimated glomerular filtration rate and body weight were identified as significant covariates for clearance and the volume of distribution, respectively. A model-based simulation was conducted to explore the probability of reaching the target therapeutic range when various dose regimens were administered according to the body weight and renal function. The simulation results indicated that the amikacin dosage should be determined based on the body weight, and for patients who weigh over 70 kg, it is necessary to adjust the dose according to renal function. In conclusion, the optimal pharmacotherapy of amikacin for patients with NTM-PD was recommended based on the population pharmacokinetic model, which is expected to enable the personalization of drug therapy and improve the clinical outcomes of amikacin therapy.

Purpose To investigate intraocular pharmacokinetics of 10-fold dose of intravitreally injected ranibizumab compared with the conventional dose in an experimental model. Methods Ranibizumab 30 µL at 10 mg/mL (conventional) and 100 mg/mL (10-fold) doses was injected separately into each eye of 28 rabbits. Ranibizumab concentrations in the aqueous humor, vitreous, and retina were estimated at each time period after injection, using enzyme-linked immunosorbent assay. The pharmacokinetic properties of ranibizumab were determined using a one-compartment model in all three ocular tissues. The time-concentration profile and predictive trends were plotted to determine drug efficacy in the retina. Results Maximum concentrations after conventional and 10-fold dosing were observed in the retina at 1 and 4 days after injection, respectively. The half-life of ranibizumab after conventional and 10-fold dosing did not differ in the anterior chamber and vitreous, whereas the half-life was prolonged approximately twice with the 10-fold dose in the retina (36.74 h vs. 76.85 h) and serum (91.93 h vs. 179.01 h). Similarly, the estimated time for ranibizumab concentration in the retina over 27 ng/mL (minimum effective concentration of ranibizumab) was prolonged approximately twice with the 10-fold dose (1315 h [55 days] vs. 2393 h [100 days]). No adverse effects were observed in either group. Conclusions The retinal half-life and concentration of ranibizumab in rabbit eyes were increased approximately twice after a 10-fold dose compared with the conventional dose. This finding indicates a possibility to lengthen the injection interval to improve the efficacy of ranibizumab in human eyes. Translational relevance Our results highlight the potential for clinical application of a high-dose (10-fold) of anti-VEGF agents to prolong the intravitreal injection intervals, simultaneously improving the drug efficacy.

Type 2 diabetes mellitus is a multifactorial condition characterized by high level of sugar in the blood. To control hyperglycemia, combination therapy is recommended if monotherapy fails to achieve glycemic control. The combination of a dipeptidyl peptidase-4 (DPP-4) inhibitor and a sodium-glucose cotransporter type 2 (SGLT2) inhibitor is a promising option of the combination therapies in terms of safety as well as efficacy. Despite of the value of combination therapy of these two agents, the pharmacokinetic drug interactions between these two classes of agents have been evaluated in a few drugs. Thus, we reviewed the potential pharmacokinetic drug interaction based on the in vitro metabolism- and transporter-mediated drug interaction information as well as drug interaction studies in human, between a DPP-4 inhibitor and a SGLT2 inhibitor which are marketed in South Korea.

A fixed-dose combination (FDC) of gemigliptin/metformin can improve the medication adherence in patients with type 2 diabetes mellitus (T2DM). In this study, the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of gemigliptin and metformin were compared between FDC and the corresponding loose combination under fasted and fed states. A two-part, randomized, open label, single-dose, two-way crossover study was conducted in healthy male subjects. Under fasted (part 1) or fed (part 2) state, 2 FDC tablets of gemigliptin/metformin sustained release (SR) 25/500 mg or loose combination with one tablet of gemigliptin 50 mg and two tablets of metformin extended release (XR) 500 mg were orally administered in each period with a 7-day washout. Serial blood samples were collected up to 48 hours to determine the drug concentration and the dipeptidyl peptidase 4 (DPP-4) activity. The concentration-time profiles of gemigliptin and metformin were similar between FDC and loose combination in both the fasted and fed states. Geometric mean ratios and 90% confidence intervals of FDC to loose combination for area under the concentration-time curve and maximum plasma concentration of gemigliptin and metformin were within the bioequivalence range (0.8-1.25) in both states. DPP-4 activity-time profiles of FDC were comparable to that of the loose combination, showing similar area under the DPP-4 inhibition-time curve and maximum DPP-4 inhibition between FDC and loose combination, regardless of the fasted or fed state. In conclusion, the PK/PD characteristics of gemigliptin and metformin were similar in FDC tablets and loose combination both in fasted and fed states. Trial registration ClinicalTrials.gov Identifier: NCT03355014.