Validation of a sensitive LC–MS assay for quantification of glyburide and its metabolite 4-transhydroxy glyburide in plasma and urine: An OPRU Network study

Glyburide (glibenclamide, INN), a second generation sulfonylurea is widely used in the treatment of gestational diabetes mellitus (GDM). None of the previously reported analytical methods provide adequate sensitivity for the expected sub-nanogram/mL maternal and umbilical cord plasma concentrations of glyburide during pregnancy. We developed and validated a sensitive and low sample volume liquid chromatographic–mass spectrometric (LC–MS) method for simultaneous determination of glyburide (GLY) and its metabolite, 4-transhydroxy glyburide (M1) in human plasma (0.5 mL) or urine (0.1 mL). The limits of quantitation (LOQ) for GLY and M1 in plasma were 0.25 and 0.40 ng/mL, respectively whereas it was 1.06 ng/mL for M1 in urine. As measured by quality control samples, precision (% coefficient of variation) of the assay was <15% whereas the accuracy (% deviation from expected) ranged from −10.1 to 14.3%. We found that the GLY metabolite, M1 is excreted in the urine as the glucuronide-conjugate.