The pharmacovigilance of complementary medicines: unpacking the complexities

Abstract

Complementary medicines in South Africa are defined as substances originating from natural sources such as plants, fungi, and minerals, intended to support physical or mental well-being. Unlike allopathic medicines, which are pure chemical compounds requiring registration through rigorous safety and efficacy dossiers, complementary medicines can be registered without such evidence. While allopathic medicines are backed by clinical trials, complementary medicines, especially herbal products, often lack robust clinical data. This disparity highlights the importance of pharmacovigilance (PV) to monitor adverse reactions (ADRs) and potential interactions in complementary medicines.

Complementary herbal medicines (Category D) fall within the regulatory ambit of the South African Health Products Regulatory Authority (SAHPRA), under the Medicines and Related Substances Act 101 of 1965. These products, however, are challenging to regulate due to variability in constituency, batch-to-batch inconsistencies, and a lack of clinical trial evidence. Herbal medicines, composed of multiple active compounds, are particularly complex, with potential synergistic or antagonistic interactions with conventional medicines complicating their safety profiles. Despite their widespread use, adverse drug reactions (ADRs) from herbal products remain undetected and underreported, often due to a lack of standardisation, insufficient clinical studies, and health illiteracy among consumers.

This paper proposes a methodology for investigating ADRs from complementary medicines, including understanding the formulation, clinical presentation, and phytochemical composition. By improving pharmacovigilance practices and fostering greater collaboration among experts, a more comprehensive safety profile for herbal-based medicines can be developed, ultimately benefiting public health.