An open-label, multiple-dose study to assess the pharmacokinetics and tolerability of sitagliptin/metformin fixed-dose combination (FDC) tablet in healthy Chinese adult subjects.

AIM: This study investigated the pharmacokinetics of sitagliptin and metformin after multiple oral doses of the sitagliptin/metformin fixed-dose combination (MK0431A) tablet in healthy Chinese volunteers.

METHODS: This was a singlecenter, randomized study in 24 healthy adults. Subjects received twice-daily doses of MK0431A 50-mg/500-mg tablet and 50-mg/850-mg tablet for 7 days. Serial blood and urine samples were collected at predefined time points for bioassay of sitagliptin and metformin. Safety was assessed throughout the study.

RESULTS: Based on consecutive trough concentrations, the steady states of sitagliptin and metformin were reached after twice-daily administration of MK0431A tablets for 5 days. After the last dose, the mean ± SD (standard deviation) peak sitagliptin concentration of 167.3 - 22.52 and 174.1 ± 22.16 ng/mL was reached in a median t_max of 2.25 - 3 hours. The mean ± SD Cmax of metformin appeared in a median tmax of 1.75 - 2.25 hours at 888.3 ± 195.19 and 1,337 ± 269.19 ng/mL with MK0431A 50 mg/500 mg and 50 mg/850 mg, respectively Mean ± SD AUC012h of sitagliptin was between 1,404 ± 147.48 and 1,374 ± 179.12 h×ng/mL, while mean ± SD AUC0-12h of metformin were 6,015 ± 854.98 and 8,587 ± 1,715.93 h×ng/mL with MK0431A 50 mg/500 mg and 50 mg/850 mg, respectively. Approximately 75% sitagliptin and 40% metformin were excreted unchanged in the urine, corresponding to a renal clearance of 17.84 - 18.27 L/h for sitagliptin and 27.11 - 27.94 L/h for metformin.

CONCLUSION: No clinically-significant pharmacokinetic difference was identified between Chinese and foreign healthy volunteers regarding sitagliptin and metformin with multiple doses of MK0431A tablets. The treatments were well tolerated.