Pharmacokinetic comparison of a new glimepiride 1-mg + metformin 500-mg combination tablet formulation and a glimepiride 2-mg + metformin 500-mg combination tablet formulation: a single-dose, randomized, open-label, two-period, two-way crossover study in healthy, fasting Korean male volunteers.
BACKGROUND
Coadministration of glimepiride and metformin has been used to achieve glucose control. Because compliance with a multiple medication regimen can be difficult for some patients, combination tablets of glimepiride + metformin might be a suitable alternative for these patients.


OBJECTIVE
This study was conducted to compare the pharmacokinetics of test and reference formulations of glimepiride + metformin fixed-dose combination tablets under fasting conditions to meet the regulatory requirements for marketing approval of a new drug in Korea.


METHODS
This was a single-dose, randomized, open-label, 2-period, 2-way crossover study conducted between March 2007 and May 2007. Healthy fasting Korean men were randomized to 1 of 2 dosing sequences: a single oral administration of a fixed-dose glimepiride 1-mg + metformin 500-mg combination tablet (test) followed by single oral administration of a fixed-dose glimepiride 2 mg + metformin 500 mg combination tablet (reference), separated by a 1-week washout period between doses; or a single oral administration of a fixed-dose glimepiride 2-mg + metformin 500-mg combination tablet followed by single oral administration of a fixed-dose glimepiride 1 mg + metformin 500-mg combination tablet, separated by a 1-week washout period between doses. Serial samples of blood were collected up to 24 hours after oral administration, and drug concentrations in plasma were determined by HPLC-MS/MS. Tolerability was assessed based on adverse events and changes in clinical parameters. Serious adverse events included those that resulted in death, a life-threatening condition, congenital anomaly or birth defect, or required hospitalization or prolongation of existing hospitalization.


RESULTS
A total of 30 healthy male subjects (mean age, 25.6 years [range, 20-36 years]; weight, 69.5 kg [range, 58.2-90.7 kg]) participated in the study. After administration of the test and reference formulations, glimepiride was rapidly absorbed, reaching C(max) with a median T(max) of 1.75 and 2.0 hours, respectively, and then declined exponentially with an average t(1/2) of 8.2 and 8.5 hours. The individual C(max) and AUC(last) of glimepiride were observed to be proportionally increased according to the administered glimepiride dose. The mean (SD) dose-normalized Cmax values of glimepiride 1 and 2 mg were 168.2 (54.9) and 149.9 (47.4) ng/mL/mg, respectively; the mean dose-normalized AUC(last) values of glimepiride 1 and 2 mg were 681.5 (190.3) and 635.8 (194.1) ng x h/mL/mg. Individual plots of dose-normalized C(max) and AUC(last) values identified a similarity between the 2 groups but no significant between-group differences. A total of 25 adverse events (12 after the test dose and 13 after the reference dose) were reported by 13 of the 30 subjects. All adverse events were considered mild. Twenty-one adverse events were considered related to the study drug (8 after the test dose and 13 after the reference dose). Adverse events believed to be related to the test formulation were diarrhea (4 cases), dizziness (1), headache (1), tingling sensation (1), and weakness (1). Adverse events believed to be related to the reference formulation were diarrhea (6 cases), headache (3), cold sweats (1), dyspepsia (1), epigastric discomfort (1), and lethargy (1). There were no clinically significant findings in the laboratory test results or vital sign monitoring during the study. There were no serious adverse events reported.


CONCLUSIONS
The C(max) and AUC(last) of glimepiride increased proportionally according to the administered glimepiride dose in this study of healthy, fasting Korean men. The safety profiles of the 2 combination tablets were comparable.
Kim
Bo-Hyung
BH
Department of Pharmacology and Clinical Pharmacology, Seoul National University College of Medicine and Hospital, Seoul, Korea.
Shin
Kwang-Hee
KH
Kim
Jaewoo
J
Lim
Kyoung Soo
KS
Kim
Kyu-Pyo
KP
Kim
Jung-Ryul
JR
Cho
Joo-Youn
JY
Shin
Sang-Goo
SG
Jang
In-Jin
IJ
Yu
Kyung-Sang
KS
D000328:Adult; D019540:Area Under Curve; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D004338:Drug Combinations; D005215:Fasting / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D008297:Male; D008687:Metformin / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D013453:Sulfonylurea Compounds / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D013607:Tablets; D055815:Young Adult
D004338:Drug Combinations; D007004:Hypoglycemic Agents; D013453:Sulfonylurea Compounds; D013607:Tablets; C057619:glimepiride; D008687:Metformin