Determination of synthetic drugs as adulterant in herbal anti-diabetic medicines by HPLC

Abstract

Herbal medicines are increasingly being used in both preventative and treatment-based medicines and tonics because consumers perceive herbal drugs as “natural” safe, harmless and free from adverse side effects. However, adulteration of herbal drugs is very common nowadays and counterfeit drug manufacturers thrives success by exploiting the trust of the patients on herbal medicine. As diabetes is one major chronic disease, patients with diabetes comply with herbal medicines almost all the time for overall well-being and better control of the disease. This makes anti-diabetic herbal drugs an easy target for the counterfeiters. What patients fail to understand is, herbs are filled with numerous bioactive molecules which can interact with the prescription oral hypoglycemic drugs and can lead to serious adverse effects. Furthermore, diabetic patients require multiple drug therapy, which put them at risk of frequent drug interactions between the herbal drugs and the synthetic medicines. In the worst-case scenario, taking herbal drugs that are adulterated with synthetic oral hypoglycemics along with prescription oral hypoglyecmics can lead to overdose and acute hypoglycemia followed by death. Therefore, this experiment is aimed at determining the presence of synthetic oral hypoglycemics in herbal anti-diabetic formulations. Herbal anti-diabetic drugs available at the local market of Dhaka were collected as samples for the experiment. Metformin and Glimepiride were considered as reference standards for the experiment. Samples and standards were subjected to HPLC for analysis with acetonitrile: Phosphate buffer (pH 2.1) at a 70:30 ratio as the mobile phase. This mobile phase ratio provided effective elution of both of the standards at distant retention times, which helped with clear identification and identification of both of the standards. The devised method was also successful in clearly identifying and quantifying substances present at the samples (herbal anti-diabetic drugs). From 25 tested samples 16 samples confirmed the presence of adulterants which concluded that 64% of the samples were adulterated. This high rate of drug adulteration inside the capital gives an easy assumption of equal or higher rate of drug adulteration in the outskirt areas and these calls for more sensitive QC methods and stricter regulations to control such act.