Validation of an LC–MS/MS method for analysis of anti‐diabetic drugs in botanical dietary supplements labeled for blood sugar management

We developed and validated a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to detect and quantitate 14 anti-diabetic, 2 anti-obesity and 3 cholesterol-lowering drugs in botanical dietary supplements marketed for blood sugar management. Many botanical dietary supplements which carry label statements related to blood sugar management are available over the internet. Potential adulteration of such dietary supplements with anti-diabetic and other prescription drugs, some of which have been removed from the market due to adverse events, is of concern. No significant matrix effects were observed and mean recoveries of all 19 analytes from a single product matrix were 88 to 113% at spiking concentrations from 500 to 2000 μg/g. Mean recoveries of metformin, phenformin, and sibutramine from matrices prepared from multiple product composites ranged from 93 to 115% at a spiking concentration of 100 μg/g. The relative standard deviations (RSD) (%) of intra-day analyses ranged from 0.2 to 13 for all recovery studies. Eighty dietary supplements obtained in the U.S. and carrying label statements related to blood sugar management were analyzed using this method and none were found to be adulterated with the above 19 drugs. Two products obtained outside of the U.S. and known to be adulterated were also analyzed by this method and found to contain phenformin, glibenclamide, and sibutramine. This method provided satisfactory selectivity, linearity, accuracy, precision, and sensitivity for rapid determination of 19 drugs and has broad applicability for the analysis of dietary supplements for possible adulteration with these compounds.