Safety profile of herbal medicines submitted for marketing authorization in Tanzania: a cross-sectional retrospective study.

BACKGROUND: The popular use of herbal medicines necessitates national regulatory authorities to have efficient mechanisms for the control of these products including marketing authorization (MA) and safety follow-up. Herbal medicines like conventional medicines require assessment of efficacy, safety and quality information before MA can be granted. However, the complete proof of safety is mainly based on the history of the long-term traditional use. Herbal medicines can cause adverse reactions due to various factors and thus require clinical trials to ensure their safety. Herbal medicines treatment practices involve combinations of different plants to achieve the desired effect while multiple herbal components have been known to cause herbal-herbal toxicity and interactions due to variety of complex active ingredients in plants. Compliance with regulatory requirements on herbal medicines has been shown to be difficult for manufacturers since different countries have different regulatory requirements with wide variations which results in the MA of very few herbal medicines. Limited studies on dossiers of marketing authorization of herbal medicines have been performed in other countries, with no studies in African regulatory system settings. The aim of this study is to determine the type of safety documentation that is submitted on herbal medicines application dossiers to support MA in Tanzania.

METHODS: A cross-sectional retrospective study of herbal medicines dossiers submitted at the Tanzania Medicines and Medical Devices Authority from 2009 to 2020 was conducted.

RESULTS: As many as 75% of the herbal products applications were combination products made by more than one herbal substance or plant. Out of 84 dossiers subjected to analysis the majority did not provide evidence of preclinical (55%) and clinical safety data (68%). Evidence of safety data in humans was mostly from the literature (70%) and not manufacturers' clinical studies. Quality parameters with safety implications were not included in 48% and 23% of the active herbal substance and finished product specifications, respectively.

CONCLUSION: Analysis of the herbal medicine dossiers submitted showed major deficiencies of safety data to support MA. Manufactures need to provide evidence to support the safety of their products for evidence-based regulatory decisions and to avoid multiple reviews of the applications.