Abstract: AIM: To develop a sensitive liquid chromatography tandem mass spectrometry(HPLC-MS/MS)method for analyzing glimepiride(G)and its active metabolite hydroxyl-glimepiride(M₁)in human plasma.METHODS: G and M₁ were extracted from plasma samples by ethyl acetate after acidification,with gliclazide (IS) serving as an internal standard. The analytes went through the column of Phenomenex Gemini C₁₈ (50 mm× 3.0 mm,5 μm) with mobile phase methanol-water-formic acid (80∶20∶0.1) and were analyzed under the multiple reaction monitoring mode using the eletrospray ionization (ESI) technique. The ion pairs being detected were( m/z) 491.4→352.4,507.4→352.4,324.4→127.2,respectively.RESULTS: The standard curves of G and M₁ were linear in the range 1.25-400 ng/mL and 0.313-100 ng/mL,with a low limit of quantification of 1.25 and 0.313 ng/mL.The intra and inter day RSD were below 10%,with recovery rates ranging from 96.4% to 102.5%.CONCLUSION: The method is simple, rapid, sensitive, and suitable for the determination of glimepiride and its metabolite in human plasma.

Key words: HPLC-MS/MS, Glimepiride, Hydroxyl-glimepiride, Plasma concentration