Blood samples were collected up to 24-h postdose on day 6 ( gemigliptin ) and day 7 ( gemigliptin and glimepiride ) following treatment A , and on day 1 ( glimepiride ) following treatment B. Concentrations of gemigliptin , glimepiride , and metabolites were determined using validated liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) .