Adulteration of herbal antidiabetic products with undeclared pharmaceuticals: a case series in Hong Kong

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Proprietary Chinese medicines (pCMs), generally considered to be natural and harmless, are commonly used for many indications, including diabetes mellitus. Adulteration of pCMs with undeclared pharmaceuticals has been reported previously. However, a detailed study investigating the problem of adulterated herbal antidiabetic products and their associated toxicities is largely lacking. WHAT THIS STUDY ADDS • This study shows the severity of the under-recognized problem of adulteration of herbal antidiabetic products with undeclared pharmaceuticals, including both registered and banned drugs. Potentially fatal adverse effects could result from the use of these illicit products. AIMS The current study aims to examine the problem of adulteration of herbal antidiabetic products with undeclared pharmaceuticals, including both registered and banned drugs. METHODS All cases involving use of adulterated herbal antidiabetic products referred to a tertiary centre for clinical toxicology analysis from 2005 to 2010 inclusive were retrospectively reviewed. The patients' demographic characteristics, clinical presentations, medical history, drug history and the analytical findings of the herbal antidiabetic products were studied. RESULTS A total of 27 cases involving use of 29 adulterated herbal antidiabetic products were identified. Seventeen of the patients (63%) had clinical toxicities associated with the illicit products. Hypoglycaemia was the most common adverse effect, followed by lactic acidosis. Analysis of the 29 illicit herbal antidiabetic products revealed eight undeclared registered or banned oral antidiabetic agents, namely glibenclamide (n= 22), phenformin (n= 18), metformin (n= 6), rosiglitazone (n= 6), gliclazide (n= 2), glimepiride (n= 2), nateglinide (n= 1) and repaglinide (n= 1). Non-antidiabetic drugs were also detected in some products. Up to four adulterants were detected within the same product. CONCLUSIONS Adulteration of herbal antidiabetic products with undeclared pharmaceuticals is a significant yet under-recognized problem. Patients taking these illicit products could be at risk of potentially fatal adverse effects. It is important to educate the public to avoid taking pCMs of dubious source. Effective regulatory measures should be put in place to address the problem.