Development of a new LC-MS/MS method for the simultaneous identification and quantification of 13 antidiabetic drugs in human hair.

Oral antidiabetics are the drugs used to control blood sugar in diabetic subjects. The greatest risk of using these drugs is hypoglycaemia, which can be fatal if managed inappropriately. The diagnosis of hypoglycemia may be simple in diabetic subjects but can become a challenge in subjects with no history of exposure to these drugs. The major interest of testing for these compounds in hair is in the case of unexpected hypoglycaemias, as it enables discrimination between hypoglycaemias caused by antidiabetics and other reasons (e.g. insulinoma). Therefore it is important for a toxicology laboratory to screen for antidiabetics in hair due to the large window of detection this matrix allows associated to its long stability over time. In this study, a method has been developed and validated using liquid-chromatography coupled to tandem mass spectrometry for the analysis of 13 oral antidiabetics in hair. After addition of three different internal standards (hydroxy-tolbutamide-d9 for sulfonylureas, repaglinide-ethyl-d5 for glinides and vildagliptin-d3 for gliptins) and incubation in an ultrasonic bath in methanol, the hair was dissolved in NaOH and then subjected to liquid-liquid extraction. The validation procedure demonstrated an acceptable linearity for all compounds between 1 and 50,000 pg/mg. LOD and LOQ were between 0.5 and 5 pg/mg and 1-10 pg/mg respectively. Repeatability and reproducibility were below 20 % at two concentrations for all the analytes. The method was successfully applied to the hair of 18 diabetic patients under treatment of oral antidiabetics. The hair tested positive for gliclazide (3-21,400 pg/mg), sitagliptin (1.4-1.8 pg/mg), vildagliptin (3.3 - 1,740 pg/mg) and repaglinide (14.1 pg/mg).