Signal Detection and Assessment of Herb-Drug Interactions: Saudi Food and Drug Authority Experience

Numerous investigations on herbal medicine that have been undertaken in the past several years demonstrate the general acceptance of its safety. The Saudi Food and Drug Authority (SFDA) established the Herb-Drug Interaction (HDI) project to detect and assess potential HDIs to ensure safety. The aim is to detect safety signals and assess them based on available evidence.

First, SFDA-registered herbal products (n = 30) were selected and prioritized based on commonly used herbs. Second, reported potential HDIs were retrieved from the World Health Organization global database of individual case safety reports (VigiBase), AdisInsight^®, and the Natural Medicines database. We excluded drugs non-registered by SFDA and labeled interactions in the product information of SFDA, the US Food and Drug Administration (FDA), and the European Medicines Agency (EMA). Finally, a comprehensive evaluation of potential HDIs was carried out using several evidence sources: literature, global cases, local cases, and other relevant documents. The Drug Interaction Probability Scale (DIPS) scale was used to assess the probability of a causal relationship between the interacting herb and drug and the event.

The search yielded 566 potential signals, and 41 had published evidence and were referred for assessment. The assessment results using DIPS were: 22 possible (53.6 %), 7 probable (17%), and 12 doubtful (29.2%) interactions. The recommendation was to include probable HDIs in the product information, including turmeric-tacrolimus, etoposide-Echinacea, Ginkgo biloba-ibuprofen, green tea-warfarin, and licorice-thiazides interactions.

The HDI project assessed the screening and identification of potential HDIs. The action plan of this project can be used in post-marketing activities to identify potential drug interactions.