Dieting – a very risky business? Simultaneous determination of anti-diabetic and weight-loss agents in herbal and dietary supplements

Abstract

The presence of undeclared pharmaceuticals, including drugs that have been withdrawn from the market, in anti-diabetic and weight-loss herbal and dietary supplements can pose a serious health risk to consumers; they also undermine confidence in legitimate products. To protect consumers from potentially harmful products that are marketed as dietary supplements, the Drug QC Laboratory, Qatar is involved in the testing of herbal and dietary products. Traditionally this testing has required a combination of several analytical methods which presents a substantial investment of time and resources. To improve laboratory efficiency a single UPLC-MS/MS method was developed for the supplement screening followed by a confirmatory method based on multiple reaction monitoring (MRM) analysis. Screening analysis comprised LC/MS with automated searching against an in-house generated MS spectral library. Confirmation and quantification was performed by MRM analysis. The developed method was applied to 654 supplements submitted to our laboratory in 2014-15. Analysis revealed that 42 herbal anti-diabetic and weight lost products were tainted with undeclared registered or banned drugs, namely sibutramine (n = 30), phenolphthalein (n = 21), glibenclamide (n = 4), metformin (n = 4), phenformin (n = 2), pioglitazone (n = 1), fluoxetine (n = 2), orlistat (n = 1), methylephedrine (n = 1) and methamphetamine (n = 2). Five hot beverages tea and coffee were found to contain a combination of sibutramine and phenolphthalein.