Feasibility study of nonclinical safety assessments on homeopathic preparations using the example of protoanemonin in Pulsatilla pratensis L.

Homeopathy is a world-wide available form of complementary therapy, which has a tradition of 200 years. Due to the long history of clinical use, i.e. reflected by the first edition of the Homeopathic Pharmacopoeia of the US of 1914, the conduct of toxicological studies is not required if the safety has been otherwise substantiated. The aim of this article is to establish a risk assessment procedure without full toxicological examination, using homeopathic preparations from Pulsatilla pratensis L. as an example. The literature review shows that protoanemonin is the most relevant constituent of these plants regarding potential toxicity. Based on structural alerts protoanemonin is classified as a Cramer class III compound with the threshold of toxicological concern (TTC) of 180 μg/day in adults. Neither computer aided toxicology methods (Toxtree and Derek Nexus®) nor a literature search revealed any evidence of genotoxic, carcinogenic or teratogenic potential of protoanemonin. The protoanemonin exposure from a maximum daily dose of a typical homeopathic preparation of P. pratensis L. does not exceed the TTC. The presented method is transparent, reproducible and applicable to other homeopathic substances as a use-case scenario for computational toxicology in order to evaluate an approach for safety assessment of homeopathic medicinal products.