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Mar 14, 2014 - This study evaluated possible pharmacodynamic and pharmacokinetic interactions between gemigliptin and metformin and investigated their ...
Clin Drug Investig (2014) 34:383–393 DOI 10.1007/s40261-014-0184-3

ORIGINAL RESEARCH ARTICLE

Pharmacokinetic and Pharmacodynamic Interaction Between Gemigliptin and Metformin in Healthy Subjects Dongseong Shin • Young Min Cho • SeungHwan Lee • Kyoung Soo Lim • Jeong-Ae Kim • Ji-Yung Ahn • Joo-Youn Cho • Howard Lee • In-Jin Jang • Kyung-Sang Yu

Published online: 14 March 2014 Ó Springer International Publishing Switzerland 2014

Abstract Background and Objective Gemigliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor used in the treatment of type 2 diabetes mellitus. This study evaluated possible pharmacodynamic and pharmacokinetic interactions between gemigliptin and metformin and investigated their tolerability. Methods A randomized, open-label, multiple-dose, threetreatment, three-period, three-sequence crossover study was conducted in healthy male subjects. Twenty-seven subjects received gemigliptin (50 mg once daily), metformin (1,000 mg twice a day), or both drugs for 7 days per dosing period. Blood samples were drawn over 24 h on the seventh day of each period for pharmacokinetic and pharmacodynamic evaluations, including plasma DPP-4 activity and total/active glucagon-like peptide-1 (GLP-1) levels. Meal tolerance tests were conducted for pharmacodynamic assessment on the eighth day. Safety and tolerability were

evaluated using adverse events, vital signs, ECGs, and clinical laboratory tests. Results Coadministration of gemigliptin and metformin had no significant effect on the pharmacokinetics of gemigliptin or metformin. The inhibition of DPP-4 by gemigliptin was not affected by coadministration with metformin. Cotherapy of gemigliptin and metformin showed additional effects by increasing plasma active GLP-1 concentrations and lowering serum glucose levels. The plasma glucagon level was lower in co-therapy than with metformin monotherapy. The coadministration of gemigliptin and metformin was welltolerated without serious adverse events. Conclusions Coadministration of gemigliptin and metformin showed beneficial anti-diabetic effects without pharmacokinetic drug–drug interactions.

Key Points

ClinicalTrials.gov registry number: NCT01426399.

Pharmacokinetic interaction was not significant in co-therapy of gemigliptin and metformin.

Electronic supplementary material The online version of this article (doi:10.1007/s40261-014-0184-3) contains supplementary material, which is available to authorized users.

Metformin had no effect on dipeptidyl peptidase-4 (DPP-4) activity after administration of gemigliptin.

D. Shin  S. Lee  K. S. Lim  J.-Y. Cho  H. Lee  I.-J. Jang  K.-S. Yu (&) Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Korea e-mail: [email protected] Y. M. Cho Department of Internal Medicine, Seoul National University College of Medicine and Hospital, Seoul, Korea J.-A. Kim  J.-Y. Ahn LG Life Sciences, Ltd., Seoul, Korea

Co-therapy with gemigliptin and metformin had the additional effects of increasing active glucagon-like peptide-1 (GLP-1) and decreasing glucose compared with gemigliptin or metformin monotherapies.

1 Introduction Glucose-stimulated insulin secretion is potentiated by incretin hormones, including glucose-dependent insulinotropic polypeptide (GIP) from the enteroendocrine K cells

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and glucagon-like peptide-1 (GLP-1) from enteroendocrine L cells, in a glucose-dependent manner [1, 2]. GLP-1 stimulates insulin secretion from pancreatic b cells, suppresses glucagon secretion from pancreatic a cells, and slows gastric emptying [3, 4]. GIP also stimulates insulin secretion, but it does not suppress glucagon secretion or modulate the rate of gastric emptying [5]. GLP-1 maintains its insulinotropic action, but GIP does not elicit insulin secretion in patients with type 2 diabetes mellitus [6], which suggests that reduced incretin-mediated insulin secretion plays a role in the pathophysiology of type 2 diabetes [7]. Therapies that exploit incretin hormones are in clinical development for the treatment of type 2 diabetes, and studies on those therapies have largely focused on GLP-1 rather than GIP [2]. Incretin hormones are rapidly degraded by dipeptidyl peptidase-4 (DPP-4), a cell surfaceanchored and soluble circulating peptidase that cleaves N-terminal dipeptides and inactivates endogenous GLP-1 and GIP (Fig. 1) [8, 9]. Therefore, DPP-4 inhibitors have been developed as incretin enhancers to increase glucosedependent insulin secretion and decrease glucagon secretion for the treatment of type 2 diabetes [10]. Metformin is a biguanide, oral anti-diabetes drug that is currently recommended as a first-line treatment for patients with type 2 diabetes [11]. Metformin suppresses hepatic glucose production, increases glucose utilization in the gut, and increases peripheral glucose disposal (Fig. 1) [12]. If metformin monotherapy fails to meet target glycemic goals, the addition of a sulfonylurea, a thiazolidinedione, a DPP-4 inhibitor, a GLP-1 receptor agonist, or basal insulin may be considered for second-line treatment [11]. Among the candidate second-line agents, the DPP-4 inhibitor has Fig. 1 The proposed mechanisms of dipeptidyl peptidase-4 inhibitor and metformin action. DPP-4 dipeptidyl peptidase-4, GLP-1 glucagon-like peptide-1

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more merit due to its low risk of causing hypoglycemia and neutrality with respect to weight gain [11]. DPP-4 inhibitors and metformin partially share the target pathway, and the combined use of DPP-4 inhibitors and metformin has various anti-diabetic effects via enhancement of insulin secretion, GLP-1 effects, and reductions in hepatic glucose production through independent pathways [12, 13]. There are several fixed-dose combinations using oral metformin with a DPP-4 inhibitor that are available for type 2 diabetes treatment. However, the potentially complementary effects associated with coadministration are not completely understood [9]. Gemigliptin is a newly developed DPP-4 inhibitor that is orally bioavailable. Gemigliptin was well-tolerated in a previous single- and multiple-dose phase I clinical study in healthy Korean subjects [14, 15], and it inhibited DPP-4 activity by 80 % over 24 h [14]. Gemigliptin monotherapy administered as 50 mg once daily improved glycosylated hemoglobin (HbA1c), fasting plasma glucose (FPG) levels, oral glucose tolerance test results, b cell function, and insulin sensitivity measures, and it was well-tolerated in clinical trials of Korean and Indian patients with type 2 diabetes [16, 17]. The aim of the present study was to evaluate the pharmacokinetic and pharmacodynamic interaction of gemigliptin and metformin at steady state.

2 Methods 2.1 Study Population Healthy Korean male subjects aged 20–45 years were enrolled for this study. Participants were included if they

PK/PD Interactions Between Gemigliptin and Metformin

had a body mass index (BMI) of 18.0–27.0 kg/m2, a total body weight of 55–90 kg, and an FPG level of 70–125 mg/ dL. Participants who had a clinically significant medical history, physical examination findings, 12-lead ECG readings, or clinical laboratory testing results were excluded. Participants who showed creatinine clearance by Cockcroft–Gault equation under 80 mL/min were also excluded for this study. The objective and contents of this study were fully explained, and written informed consents were obtained prior to enrollment.

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(98 %) in water and stored at -70 °C until analysis. The other two 0.5 mL plasma samples (without 5 % formic acid) were frozen and stored at -70 °C until analysis. Urine samples were collected over 0–6, 6–12, and 12–24 h post-dose on day 7. Two 0.8 mL urine samples were mixed 1:1 with 5 % formic acid (98 %) in water, and the other two samples of unmixed 0.8 mL urine samples were frozen and stored at -70 °C. Blood and urine samples were analyzed using positive ion liquid chromatography– tandem mass spectrometry (LC–MS/MS) (LG Life Sciences Ltd., Daejeon, Korea).

2.2 Study Design 2.4 Pharmacodynamic Assessment The Institutional Review Board of Seoul National University Hospital (SNUH) (Seoul, Korea) approved this randomized, open-label, multi-dose, three-treatment, three-sequence, three-period crossover study, which was conducted in accordance with the Declaration of Helsinki and Korean Good Clinical Practice (ClinicalTrials.gov registry number: NCT01426399). The 30 participants who met the predefined criteria were randomly assigned to one of three sequences of three treatments: gemigliptin 50 mg once daily for 8 days, metformin 1,000 mg twice a day for 7 days and once in the morning of the eighth dosing day, and coadministration of gemigliptin 50 mg once daily for 8 days and metformin 1,000 mg twice a day for 7 days and once in the morning of the eighth dosing day. A washout period of 7 days followed the last dose of the previous treatment period. The following three sequences were used: treatment combination of gemigliptin monotherapy ? metformin monotherapy ? cotherapy of gemigliptin and metformin (sequence A); co-therapy with both drugs ? gemigliptin monotherapy ? metformin monotherapy (sequence B); or metformin monotherapy ? co-therapy of both drugs ? gemigliptin monotherapy (sequence C). Participants were administered the study drug until day 5 during outpatient visits. Participants in the metformin monotherapy and co-therapy treatment periods took metformin by themselves in the evening at home; they were admitted to the Clinical Trials Center on the evening of day 5 and were discharged after the meal tolerance test (MTT) on day 8. Participants took the study drug with 240 mL water in a fasting state from days 1 to 8. 2.3 Pharmacokinetic Assessment Blood samples at steady state (day 7) were collected before dosing (0 h) and 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, and 24 h after study drug administration during each period to evaluate pharmacokinetics. Blood samples at each sampling time were collected in heparin tubes and centrifuged at 1,650 g for 10 min at 4 °C. Two aliquots of supernatant (each 0.3 mL) were mixed 1:1 with 5 % formic acid

Blood samples were obtained for the measurement of DPP-4 activity pre-dose on days 5 and 6, before dosing (0 h), and 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, and 24 h after dosing on day 7 for steady state. Blood for DPP-4 activity (3 mL) was contained in EDTA tubes and centrifuged for 10 min at 3,000 rpm. Two 0.3 mL aliquots were transferred to cryotubes, frozen at -20 °C for 24 h, and stored at -70 °C until analysis. An MTT was conducted 1 h post-dose on day 8. The total energy of the provided standard meal was approximately 787 calories (68 % carbohydrate, 17 % protein, and 15 % fat). Subjects were required to eat the meal within 10 min. Blood samples for active/total GLP-1, glucose, glucagon, insulin, and C-peptide were collected at 0, 1, 1.25, 1.5, 2, 2.5, and 3 h relative to drug administration. Blood samples (3 mL) for active/total GLP-1 were immediately collected in BDTM P700 tubes containing a DPP-4 protease inhibitor (Becton, Dickinson and Company, Franklin Lakes, NJ, USA), shaken gently, and left on ice for up to 1 h. Samples were centrifuged for 10 min at 2,000 g at 4 °C. Four 250 lL aliquots were transferred to cryotubes, frozen at -20 °C for 24 h, and stored at -70 °C until analysis. Blood (4 mL) for serum glucose and C-peptide was drawn into serum separator tubes and maintained at room temperature. Samples were centrifuged within 1 h and analyzed by the SNUH Department of Laboratory Medicine for serum glucose, and the Department of Nuclear Medicine for C-peptide. Blood (2 mL) for plasma insulin was collected in EDTA tubes, centrifuged, and analyzed within 1 h by the Department of Nuclear Medicine (SNUH). Blood (2 mL) for glucagon was extracted and stored in EDTA tubes. Samples were centrifuged for 10 min at 2,000 g within 1 h, frozen at -20 °C, and transferred to the Green Cross Reference Lab., Yongin, Korea. 2.5 Bioanalytical Methods Concentrations of plasma and urine gemigliptin, LC150636, and metformin were determined using positive ion

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LC (Agilent 1100 series; Agilent Technologies, Wilmington, DE, USA)–MS/MS (API 4000TM instrument; Applied Biosystems/MDS Sciex, Toronto, Canada). For gemigliptin and LC15-0636, chromatographic separation was performed at 30 °C using a LunaÒ C8 column (30 9 2.0 mm, 3 lm Phenomenex, Torrance, CA, USA) operated under reverse-phase conditions with a mobile phase A (10 mmol/ L ammonium acetate:acetonitrile = 90:10, v/v) with 0.1 % formic acid and a mobile phase B (10 mmol/L ammonium acetate:methanol:acetonitrile = 10:45:45, v/v) with 0.1 % formic acid. The standard curves for gemigliptin and LC15-0636 were 1.0–2,000.0 ng/mL and 5.0–1,000.0 ng/ mL, respectively. The percentage coefficient of variation [CV (%)] and mean difference (%) of precision and accuracy were 5.4 to 7.1 % and -0.9 to 5.1 % for plasma gemigliptin, and 4.4 to 6.8 % and -7.7 to 4.2 % for plasma LC15-0636, respectively. The CV and mean difference of precision and accuracy were 4.6 to 6.0 % and -4.6 to 3.7 % for urine gemigliptin, and 1.2 to 5.6 % and 5.0 to 7.0 % for urine LC15-0636, respectively. Chromatographic separation for metformin was performed at 40 °C using a phosphorylcholine (PC) hydrophilic interaction liquid chromatography (HILIC) column (2.0 mm ID 9 150 mm; Shiseido, Yokohama, Japan) operated under reverse-phase conditions with a mobile phase A (10 mmol/L ammonium acetate) with 0.1 % formic acid and a mobile phase B (acetonitrile) with 0.1 % formic acid. The standard curve range of metformin was 2.0–2,000.0 ng/mL. The CV and mean difference of precision and accuracy were 0.7 to 3.0 % and -9.1 to 12.9 % for plasma metformin, and 0.5 to 3.7 % and -2.5 to 13.7 % for urine metformin, respectively. A continuous spectrophotometric assay determined plasma DPP-4 activity using the Gly-Pro-pNA substrate (Bachem, Bubendorf, Switzerland). DPP-4 is an N-terminal serine protease that catalyzes the proteolysis from GlyPro-pNA to pNA. DPP-4 enzymatic activity was evaluated by measuring the absorbance at 390 nm, which corresponds to the cleaved product, pNA. The reaction solution consisted of 40 lL human plasma, 60 lL of 66.67 mmol/L Gly-Pro-pNA, and 83.3 mmol/L HEPES buffer (pH 7.4) in a total volume of 100 lL. The release of pNA was measured continuously for 15 min in a 96-well plate spectrophotometer (SpectraMaxÒ 340; Molecular Devices Corp., Sunnyvale, CA, USA). DPP-4 activity was calculated as the slope (mOD/min) from 4 to 14 min, and the reported unit of assay was mOD/min. The inter-assay precision of DPP-4 activity was 3.64–12.75 %. The lower limit of quantification (LLOQ) of DPP-4 activity was 1.43 mOD/ min. Active GLP-1 and total GLP-1 were measured using an ELISA kit (EZGLP1T-36K, Linco Research, St. Charles, MO, USA and EGLP-35K, Millipore, St. Charles, MO,

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USA, respectively); LLOQs were 2.0 and 1.5 pmol/L, respectively. Serum glucose levels were determined using an oxidase enzymatic assay in the range of 1–800 mg/dL. Radioimmunoassay was used to confirm the plasma glucagon level in the range of 25–500 pg/mL. Plasma insulin levels were measured using an immunoradiometric assay (IRMA) with a detection range of 0–465 lIU/mL. Serum C-peptide was measured using radioimmunoassay with a detection range of 0–30 ng/mL. 2.6 Pharmacokinetic Analysis Pharmacokinetic parameters [maximum (peak) steady-state plasma drug concentration (Cmax,ss), area under the plasma concentration–time curve during dosing interval (AUCs,ss)] for gemigliptin, LC15-0636 (active metabolite of gemigliptin), and metformin were calculated using the noncompartmental method of WinNonlinÒ version 6.2 (Pharsight Corporation, Cary, NC, USA). The Cmax,ss was directly described from the plasma concentration–time profiles. AUCs,ss on day 7 was calculated using the linear trapezoidal method in the area of concentration increase and the log trapezoidal method in the area of concentration decrease. The elimination rate constant (kz) was estimated using a regression of the log-linear decrease of the plasma concentration–time profile. The terminal elimination halflife at steady state (t‘,ss) was calculated as ln(2)/kz. Renal clearance at steady state was calculated as the cumulative amount of unchanged drug excreted in urine (Ae,ss) divided by the AUCs,ss. 2.7 Pharmacodynamic Analysis The area under the DPP-4 activity–time curve (AUECs,ss) over 24 h in steady state was estimated using the linear trapezoidal rule for pharmacodynamic evaluations. The area under the concentration–time curve from 0 h (predose) to 3 h after drug administration during the MTT (AUC3) values for active/total GLP-1, glucose, glucagon, insulin, and C-peptide were determined using the linear trapezoidal method. Maximum (peak) plasma drug concentration (Cmax) values for active/total GLP-1, glucose, insulin, and C-peptide were obtained from the observed values. The minimum activity (Emin) of DPP-4 and minimum plasma concentration (Cmin) of glucagon were determined from the observed data. 2.8 Safety and Tolerability Safety and tolerability were evaluated through adverse events (AEs) monitoring, physical examinations, vital sign measurements, 12-lead ECG, and clinical laboratory tests, including hematology, blood chemistry, and urinalysis.

PK/PD Interactions Between Gemigliptin and Metformin

2.9 Statistical Analysis SPSSÒ version 18.0 (SPSS Korea, Seoul, Korea) was used for statistical analyses. Using a mixed-effect model, ANOVA was performed to compare the 90 % confidence intervals for the geometric mean ratios of the AUCs,ss or Cmax,ss values. In the mixed-effect model, sequence, period, and treatment were considered as fixed effects, and subject nested within sequence was used as a random effect.

3 Results 3.1 Demographic Characteristics A total of 30 healthy, Korean male subjects were enrolled and randomly assigned to three sequence groups (A, B, or C). Three participants dropped out during the outpatient visits due to missing doses of the study drug: two participants in sequence A and one participant in sequence C. A total of 27 subjects (sequence A:sequence B:sequence C = 8:10:9) completed the study and were eligible for pharmacokinetic and pharmacodynamic assessments. The median (range) age, weight, height, and BMI were 26 (21–36) years, 68.8 (56.7–84.0) kg, 173.7 (163.2–189.3) cm, and 22.5 (18.7–26.6) kg/m2, respectively. The demographic characteristics of the subjects were not significantly different between sequences. 3.2 Pharmacokinetic Characteristics Co-therapy showed comparable pharmacokinetic profiles (Cmax,ss and AUCs,ss) to those of gemigliptin monotherapy and metformin monotherapy (Table 1; Fig. 2). The terminal half-life and renal clearance of individual drugs for gemigliptin monotherapy and metformin monotherapy at steady state were not significantly different compared with co-therapy (Table 1).

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gemigliptin or metformin monotherapy (Fig. 4a; Fig. S1 in the Electronic Supplementary Material). The Cmax and AUC3 values (mean ± SD) of active GLP-1 were comparable between gemigliptin and metformin monotherapy (25.1 ± 9.9 and 26.4 ± 12.9 pmol/L for Cmax and 35.8 ± 15.4 and 36.5 ± 15.8 pmolh/L for AUC3, respectively). Total GLP-1 showed different concentration–time profiles compared with active GLP-1. The mean plasma total GLP-1 concentrations for all timepoints were highest in metformin and lowest in gemigliptin (Fig. 4b). The Cmax and AUC3 values (mean ± SD) of total GLP-1 followed the same pattern, and these values were significantly different between gemigliptin monotherapy, metformin monotherapy, and co-therapy (22.5 ± 9.0, 38.4 ± 11.2, 30.7 ± 11.2 pmol/L for Cmax and 40.8 ± 24.7, 74.7 ± 23.6, 61.3 ± 25.6 pmolh/L for AUC3, respectively). The increase in serum glucose after the standard meal intake was highest in the gemigliptin and lowest in the cotherapy groups (Fig. 4c; Fig. S1 in the Electronic Supplementary Material). The Cmax and AUC3 values (mean ± SD) of serum glucose were lowest in co-therapy and were significantly different between gemigliptin monotherapy, metformin monotherapy, and co-therapy (8.4 ± 0.9, 7.5 ± 1.0, 6.7 ± 0.8 mmol/L for Cmax and 18.5 ± 1.8, 17.6 ± 1.6, 16.4 ± 1.3 mmolh/L for AUC3, respectively). Glucagon during the MTT initially increased until 0.25–0.5 h after the meal then decreased (Fig. 4d; Fig. S1 in the Electronic Supplementary Material). The Cmin and AUC3 values in gemigliptin were lower than in co-therapy or metformin. The mean plasma concentration of glucagon was highest in metformin and lowest in gemigliptin. Plasma insulin and serum C-peptide showed similar trends after meal intake (Fig. 4e, f; Fig. S1 Electronic Supplementary Material). Insulin and C-peptide levels rose as the glucose levels increased. The Cmax and AUC3 values of insulin and C-peptide were higher in gemigliptin than in either co-therapy or metformin. There were no significant differences in the Cmax and AUC3 values of insulin and C-peptide between co-therapy and metformin.

3.3 Pharmacodynamic Characteristics 3.4 Safety and Tolerability The mean DPP-4 activities in co-therapy and gemigliptin monotherapy were lower than in metformin monotherapy at all timepoints (Fig. 3). There were no significant differences in observed plasma DPP-4 Emin at steady state (Emin,ss) and AUECs,ss values [mean ± standard deviation (SD)] between co-therapy and gemigliptin (2.7 ± 0.6 and 2.6 ± 0.5 mOD/min for Emin,ss, and 93.6 ± 19.0 mODh/ min and 96.73 ± 18.2 mODh/min for AUECs,ss, respectively). The mean plasma active GLP-1 concentrations during MTT were consistently higher in co-therapy than in

Eight of the 30 participants (26.7 %) in the gemigliptin monotherapy group and 21 of the 30 participants (70 %) in metformin monotherapy reported AEs; 19 (65.5 %) of 29 subjects receiving co-therapy reported AEs. The most commonly reported AEs were diarrhea (n = 38, metformin:co-therapy:gemigliptin = 23:15:0), nausea (n = 13, metformin:co-therapy:gemigliptin = 5:8:0), abdominal discomfort (n = 9, metformin:co-therapy:gemigliptin = 6:3:0), and dyspepsia (n = 4, metformin:co-therapy: gemigliptin = 1:3:0). These gastrointestinal disorders only

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Table 1 Pharmacokinetic comparisons of gemigliptin and metformin at steady state after 7 days of administration of gemigliptin or metformin monotherapy, or co-therapy of gemigliptin and metformin Parameter

Gemigliptin (n = 27)a

Co-therapy (n = 27)a

Metformin (n = 27)a

Gemigliptin Cmax,ss (lg/L)

73.95 ± 21.80 (29.5)

68.00 ± 22.08 (32.5)

Ctrough,ss (lg/L)

13.17 ± 3.48 (26.4)

12.33 ± 3.69 (30.0)

GMR for Cmax,ss (90 % CI)

0.921 (0.840–1.010)

AUCs,ss (lgh/L)

731.52 ± 160.94 (22.0)

GMR for AUCs,ss (90 % CI)

0.911 (0.873–0.950)

tmax,ss (h)b t‘,ss (h)

1.5 [0.5–5.0] 12.08 ± 1.58 (13.1)

2.0 [0.5–8.0] 11.90 ± 1.79 (15.0)

CL/F (L/h)

54.50 ± 12.02 (22.1)

60.22 ± 13.75 (22.8)

CLR (L/h)

21.27 ± 5.73 (26.9)

21.04 ± 4.34 (20.6)

665.47 ± 149.76 (22.5)

LC15-0636 Cmax,ss (lg/L)

15.79 ± 2.70 (17.1)

14.98 ± 2.72 (18.2)

Ctrough,ss (lg/L)

2.95 ± 3.15 (106.8)

2.41 ± 3.25 (134.9)

GMR for Cmax,ss (90 % CI)

0.951 (0.881–1.027)

AUCs,ss (lgh/L)

189.51 ± 59.80 (31.6)

GMR for AUCs,ss (90 % CI)

0.931 (0.804–1.080)

tmax,ss (h)b

5.0 [1.5–24.0]

4.0 [1.0–8.0] 17.87 ± 6.23 (34.9)

180.39 ± 66.87 (37.1)

t‘,ss (h)

19.04 ± 9.33 (49.0)

Metabolic ratioc

0.27 ± 0.10 (38.1)

0.28 ± 0.11 (40.7)

CLR (L/h)

22.30 ± 8.36 (37.5)

27.25 ± 18.26 (67.0)

Metformin Cmax,ss (lg/L) Ctrough,ss (lg/L)

1,520.06 ± 559.81 (36.8) 451.90 ± 158.36 (35.0)

GMR for Cmax,ss (90 % CI)

0.871 (0.796–0.953)

AUCs,ss (lgh/L)

9,111.65 ± 2,219.36 (24.4)

GMR for AUCs,ss (90 % CI)

0.968 (0.901–1.039)

tmax,ss (h)b

1.5 [0.5–4.0]

2.0 [1.0–4.0]

1,713.54 ± 508.75 (29.7) 384.00 ± 100.41 (26.1) 9,284.88 ± 2,155.57 (23.2)

t‘,ss (h)

4.77 ± 0.93 (19.6)

4.52 ± 1.24 (27.5)

CL/F (L/h)

95.68 ± 22.63 (23.7)

95.64 ± 20.29 (21.2)

CLR (L/h)

38.14 ± 10.51 (27.6)

38.21 ± 8.50 (22.2)

AUCs,ss area under the plasma concentration–time curve during dosing interval, CL/F apparent total clearance of the drug from plasma after oral administration, CLR renal clearance of the drug from plasma, Cmax,ss maximum (peak) steady-state plasma drug concentration, Ctrough,ss trough plasma concentration at steady state, GMR geometric mean ratio, t‘,ss terminal elimination half-life at steady state, tmax,ss time to reach Cmax,ss a

Values are presented as arithmetic mean ± standard deviation (% coefficient of variation) unless specified otherwise

b

Median [range]

c

Metabolic ratio = AUCs,ss of LC15-0636/AUCs,ss of gemigliptin

occurred in treatments with metformin (co-therapy and metformin monotherapy). All AEs, except nausea, were mild and resulted in full recovery without sequela. The nausea, which was reported as moderate, occurred in co-therapy. Serious clinical or laboratory abnormalities were not reported. None of the participants discontinued the study due to AEs.

4 Discussion This clinical study provides quantitative information on drug–drug interactions between gemigliptin and

metformin. Potential pharmacokinetic, pharmacodynamic, and tolerability interactions were assessed in this randomized, multi-dose, three-way crossover study in healthy subjects. The coadministration of gemigliptin and metformin did not affect the systemic exposure of gemigliptin, its metabolite, or the total exposure of the active moiety, which exhibits twofold higher pharmacological activity of LC15-0636 (Investigator’s brochure, unpublished data on file). These results are consistent with results from combinations of other DPP-4 inhibitors and metformin [18–20]. Gemigliptin and metformin co-therapy resulted in a slight reduction in the Cmax,ss of metformin [23]. The results from

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Fig. 2 Mean plasma concentration–time profiles of gemigliptin, LC15-0636, and metformin at steady state after administration of gemigliptin or metformin alone, or their coadministration. Bars represent standard deviations. a Gemigliptin, b LC15-0636, and

c metformin at steady state after 7 days of multiple oral administration of gemigliptin 50 mg alone, metformin 1,000 mg alone, or coadministration of gemigliptin 50 mg and metformin 1,000 mg

this study show a beneficial pharmacodynamic interaction without pharmacokinetic interactions or decreased tolerability. Cytochrome P450 3A4 metabolizes gemigliptin to an active metabolite, LC15-0636 (Investigator’s brochure, unpublished data on file). P-glycoprotein (P-gp) is associated with gemigliptin transport, and multidrug-associated protein 2 (MRP2) is involved in LC15-0636 transport (Investigator’s brochure, unpublished data on file). However, metformin is not metabolized, and organic cation transporters (OCTs) and multidrug and toxin extrusion transporter (MATE) are associated with the tubular and biliary secretion of metformin [21]. As a result, gemigliptin and metformin are eliminated through independent pathways, which may explain the lack of significant

pharmacokinetic interaction between gemigliptin 50 mg once daily and metformin 1,000 mg twice a day in this study. Plasma DPP-4 activities in co-therapy and gemigliptin monotherapy were lower than metformin monotherapy at all timepoints. Both Emin,ss values in co-therapy and gemigliptin monotherapy were 14 % of those in metformin monotherapy, and both AUECs,ss values in co-therapy and gemigliptin monotherapy were 20 % of those in metformin monotherapy. Metformin did not induce a significant inhibition of DPP-4 activity in previous studies [22, 23], but other studies have reported that systemic DPP-4 activity is reduced in rodents or humans treated with metformin [12]. Our study showed that metformin did not affect DPP-4 activity, which is consistent with the previous reports [22, 23].

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Fig. 3 Mean plasma dipeptidyl peptidase-4 activity–time profiles after 7 days of multiple oral administrations of gemigliptin or metformin alone, or their coadministration. Bars represent standard deviations. DPPIV dipeptidyl peptidase-4

The extent of the increase in active GLP-1 following the standard meal in this study was similar in gemigliptin and metformin, whereas co-therapy led to an even greater increase in active GLP-1 (approximately 1.8- and 2.1-fold increase in Cmax and AUC3, respectively). Total GLP-1 also increased after the standard meal; in contrast to active GLP-1, the highest mean Cmax and AUC3 values of total GLP-1 were observed in the metformin group and the lowest in the gemigliptin group. DPP-4 inhibitors are related to a decrease in total GLP-1 in response to increased concentrations of biologically active GLP-1 [20, 24, 25]. These findings could be explained by an inhibitory feedback mechanism, which may limit further GLP-1 secretion in response to the elevated levels of the biologically active forms in the intestinal mucosa (L cells) [26– 28]. The feedback regulation of GLP-1 is mediated through paracrine somatostatin activity on L cells [5, 29]. Notably, metformin increases plasma levels of total and active GLP1 [9, 12, 30]. Therefore, these findings could explain the result that total GLP-1 after gemigliptin was lower than cotherapy in this study. DPP-4 inhibitors and metformin had complementary and additive mechanisms in the elevation of active GLP-1 in a previous study, and metformin increased total GLP-1 [9]. A similar tendency was observed in our study. Systemic exposures to insulin and C-peptide were greatest in gemigliptin. No significant differences in insulin and C-peptide levels were observed between co-therapy and metformin. The general trend of the concentration– time profile of C-peptide was similar to that of insulin. DPP-4 inhibitors suppress the degradation of endogenous GLP-1 in response to glucose increase and result in insulin secretion [31]. The increase in glucose in our study was

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lower in metformin and co-therapy than in gemigliptin therapy. Therefore, this lower level of elevated glucose may have contributed to the reduced insulin and C-peptide production in metformin and co-therapy [32]. The mean plasma glucagon level after the meal was lower in cotherapy than in metformin therapy despite the higher glucose level in metformin. Considering the direct action of glucose on pancreatic a cells, the reduced glucagon level in co-therapy suggests that the DPP-4 inhibitor suppresses glucagon release under normal physiological states [33]. Different patterns of pharmacodynamic parameters have been observed in patients with type 2 diabetes than in healthy volunteers [34]. Postprandial glucose increases were comparable between sitagliptin and metformin, and glucose levels were lowest in co-therapy [34]. However, the glucose level in the healthy subjects in this study was higher in gemigliptin than in metformin. Plasma insulin was not enhanced by either monotherapy, but co-therapy with sitagliptin and metformin promoted insulin release in patients [34]. By contrast, insulin release with co-therapy and metformin were similar but was the highest with gemigliptin. Sitagliptin monotherapy and co-therapy suppressed glucagon levels in patients, and the plasma glucagon levels were comparable between the two treatments [34]. Glucagon levels in healthy subjects were different between the three treatments; they were highest in metformin and lowest in gemigliptin. These findings suggest that gemigliptin and metformin reduce glycemic excursions via independent pathways: metformin acts directly on the liver, whereas DPP-4 inhibitors act indirectly, through GLP-1 enhancement and glucagon suppression [34]. The AEs, which were associated with co-therapy and metformin, were similar in incidence and severity. Overall, multiple coadministrations of gemigliptin and metformin were well-tolerated in healthy male subjects. However, some limitations of this clinical study were that it was conducted in a small number of healthy, young male volunteers, and it did not have a placebo control treatment group. Furthermore, the treatment period was relatively short, and the pharmacodynamics and tolerability results presented in this study only reflect normal physiology rather than the clinical pathophysiology of type 2 diabetes.

5 Conclusion Multiple coadministrations of gemigliptin and metformin showed no differences from gemigliptin monotherapy in terms of tolerability, pharmacokinetics, or inhibition of DPP-4 activity. The extent of DPP-4 inhibition was similar between gemigliptin treatment and the coadministration of gemigliptin with metformin. Active GLP-1 and glucoselowering levels showed increased effects with gemigliptin

PK/PD Interactions Between Gemigliptin and Metformin

Fig. 4 Mean concentration–time profiles of pharmacodynamic markers during meal tolerance test after multiple oral administrations of metformin monotherapy, gemigliptin monotherapy, or co-therapy. Bars represent standard deviations. a Active GLP-1, b total GLP-1, c glucose, d glucagon, e insulin, and f C-peptide. p \ 0.05 is

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statistically significant, *statistically significantly different between gemigliptin monotherapy and co-therapy, or between metformin monotherapy and co-therapy, **statistically significantly different between three treatments. GLP-1 glucagon-like peptide-1

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and metformin coadministration than with gemigliptin or metformin monotherapies. Therefore, our results suggest that combination therapy of gemigliptin and metformin may be administered with a beneficial pharmacodynamic effect without the need for dose adjustments due to pharmacokinetic interactions. Acknowledgments This study was sponsored by LG Life Sciences, Ltd. Korea. Dongseong Shin is supported by a training program grant from the Korea Healthcare Technology R&D Project, Ministry for Health and Welfare Affairs, Republic of Korea (A070001). Young Min Cho has received a lecture fee or a consultation fee from LG Life Sciences. Jeong-Ae Kim and Ji-Yung Ahn are employees of LG Life Sciences. The other authors have no conflicts of interest to disclose.

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