CONTEXT

The use of complementary and alternative medicine (CAM), particularly herbal medicine and their derived products, have been increasing. However, sporadic reports of serious adverse effects associated with the use of these products have become a source of concern. Spontaneous adverse event reporting may be used to monitor the safety of these products.

OBJECTIVE

The objectives of this study is to analyze and describe the patterns of adverse events associated with the use of Chinese Proprietary Medicine, other complementary medicine and health supplements (termed CAM products) in the Singapore Pharmacovigilance database from 1998 to 2009 and to highlight areas of safety concerns.

METHODS

Adverse events associated with CAM products reviewed by the Vigilance Branch of the Health Sciences Authority for the period 1998-2009 were collated and analyzed. The following information was extracted and collated: patient demographics, type and indication of CAM products, system-organ class affected, seriousness of the adverse event, route of administration, hospitalization status, outcome of adverse event, concomitant use of conventional medicine, adulterant testing and profession of the reporter.

RESULTS

In the period 1998-2009, 627 cases of adverse events due to CAM products were reported. Most of these 627 cases (80.2%) were found to be serious and most of the patients used CAM products for sexual performance enhancement (291, 46.4%), to relieve pain such as joint and neck pain (36, 5.9%) and for slimming purposes (27, 4.3%). Of the 627 cases, endocrine disorders constituted 22.5% and central nervous system disorders constituted 20.6%. Liver was the main organ involved in the serious cases. Twenty-two fatalities were reported and hepatotoxicity was responsible for the deaths of 10 patients during the study period.

CONCLUSIONS

In conclusion, 627 adverse event reports associated with CAM products had been successfully analyzed and described. They constituted ~3.8% of the total number of adverse events reported from 1998 to 2009. Outbreaks of severe hypoglycemia in 2008 and 2009 were associated with the use of adulterated and illegal sexual performance enhancement products. Further work to confirm the hepatotoxicity of implicated CAM products is warranted. Reporting of suspected adverse events is strongly encouraged even if the causality is not confirmed because any signs of clustering will allow rapid regulatory actions to be taken. The analysis of spontaneously reported adverse events is important in monitoring the safety of CAM products and helps in the understanding of the benefits and risks associated with the use of such products.