From cytotoxicity to clinical safety: Product-specific evidence and justified extrapolation for Cannabis and Psilocybe preparations
Year: 2026
Type: preprint
Abstract: This preprint presents a focused critical narrative review of how safety findings for Cannabis and Psilocybe preparations are transferred across products, formulations, exposures, test systems, populations, and conditions of use. The central question is not whether safety evidence can ever be extrapolated, but when such extrapolation is justified and what information is needed to support it. The review examines selected analytical, cellular, pharmacokinetic, clinical, and regulatory examples to show why category-level terms such as “Cannabis,” “CBD,” “Psilocybe,” or “psilocybin” may conceal important differences in product identity, composition, formulation, dose, route, storage, contaminants, and use conditions. Examples include: discrepancies between labelled and measured cannabinoid content; preparation- and storage-dependent variation in Psilocybe cubensis biomass; extract-specific in vitro responses; differences in systemic Δ9-THC exposure despite the same nominal THC dose; and the limits of transferring findings from a controlled synthetic-psilocybin trial to fungal biomass or other use contexts. The review argues that safety findings should remain linked to the characterized product, exposure, endpoint, population or test system, observation period, and conditions actually studied. It also distinguishes product quality from clinical safety. Conformity with compositional, manufacturing, or contaminant-related specifications does not, by itself, establish clinical interchangeability, therapeutic efficacy, or overall safety. The importance of product characterization also depends on the type of claim being made and the context in which a product is supplied. Self-produced personal use, commercial supply, and therapeutic or medicinal use do not necessarily require identical levels of quality assurance. Rather, the strength of characterization and supporting evidence should be proportionate to the specificity and consequence of the claims being made. To make safety-claim transfer more transparent, the paper proposes a claim-linked extrapolation record that explicitly documents: the source safety claim; the source and target products; composition and measurement; exposure; test system or population; endpoint and ascertainment; use, support, and observation conditions; relevant source-to-target differences; bridging evidence and justification; and residual uncertainty and disposition of the claim. This record is presented as an application of existing product-characterization and evidence-bridging principles, not as a validated checklist, universal safety score, or new regulatory standard. The review is intentionally focused rather than systematic. Its conclusions are limited to the selected and accessible evidence. Missing evidence is treated as uncertainty—not as proof of harm, but also not as evidence of equivalence. Keywords Cannabis; Psilocybe; psilocybin; cannabidiol; THC; product characterization; safety; cytotoxicity; extrapolation; evidence transfer; quality assurance; botanical drugs; psychedelic research; critical narrative review Suggested hashtags #Cannabis #Psilocybe #Psilocybin #Psychedelics #PatientSafety #DrugSafety #ProductQuality #EvidenceBasedMedicine #Toxicology #Pharmacology #OpenScience #Preprint
Author: Shiraishi, Kenjiro
Subfield: Pharmacology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7222918753
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