Advances in Methods and Techniques in Pharmacovigilance for Herbal and Traditional Medicines and Other Natural Health Products

Abstract

Many herbal and traditional medicines and other natural health products (HTMs/NHPs) are complex mixtures of chemical constituents and, like other substances used in medicine, these can cause adverse reactions. This, alongside the extensive use of HTMs/NHPs, and the ways in which these products/preparations are regulated, accessed, used, and perceived, explains the need for safety monitoring for these products.

Pharmacovigilance for HTMs/NHPs continues to rely on the analysis of spontaneous reports of suspected adverse drug reactions submitted by health professionals and, increasingly, patients. This approach has resulted in the identification of signals of several safety concerns associated with certain HTMs/NHPs, such as products containing extracts of black cohosh (Actaea racemosa L.) root/rhizome. Such signals are typically identified at a national level through manual review of reports identified following, for example, an increase in the number of reports, or another change in the reporting pattern for the herbal-product-suspected ADR combination. Few countries use statistical signal detection techniques for identifying HTM/NHP safety signals. Signal detection techniques, namely disproportionality analysis, are applied to HTM/NHP reports held in VigiBase, the World Health Organization’s (WHO) global database of individual case safety reports, maintained by the Uppsala Monitoring Centre on behalf of WHO.

Recent developments in spontaneous reporting include the implementation of direct patient reporting (which may be important for HTMs/NHPs, since these products are often used in self-treatment), changes to spontaneous reporting forms to include references to HTMs/NHPs, and the provision of public access to information on reports of suspected ADRs held by national pharmacovigilance centres and/or medicines’ regulatory authorities. Despite these initiatives, challenges in spontaneous reporting of suspected ADRs associated with HTMs/NHPs remain, particularly under-identification and under-reporting of suspected ADRs associated with these products by users and health professionals. Other developments in pharmacovigilance for HTMs/NHPs include the application of active surveillance methods, such as intensive monitoring, although this has mainly been in a research context. Other methods, such as registries, and real-world health data, including electronic medical/health records, and ‘patient-experience’ data, are at early stages in their evolution with respect to use in pharmacovigilance for HTMs/NHPs.