Comparative in vitro safety assessments of synthetized and plant-derived cannabidiol (CBD), and pharmacokinetics of synthetized CBD: evidence of similar toxicological profiles and accumulation upon repeated oral administration.

Wong E.; Bovard D.; Schlage W.; Xia W.; Isa H.; Sirbu O.; Kolli A.; Nikolajsen G.; Jensen S.; Ho J. et al. · Frontiers in toxicology · 2026

**Background & Methods** This comparative toxicology study evaluated in vitro safety profiles and pharmacokinetics of synthesized versus plant-derived cannabidiol (CBD). Four CBD sources (two synthesized brands and two plant-derived formulations) underwent in vitro testing, followed by a 21-day repeated oral dose study in male Sprague-Dawley rats using one synthesized CBD source, with blood and tissue sampling on days 1 and 21 to assess accumulation and metabolite exposure via liquid chromatography-tandem mass spectrometry. **Key Findings** • All CBD sources demonstrated comparable in vitro safety profiles with no evidence of genotoxicity or mutagenicity on micronucleus and Ames assays, similar cytotoxicity in HepaRG hepatocyte cultures, and equivalent cytochrome P450 inhibition patterns, indicating source origin (synthesized versus plant-derived) does not meaningfully affect in vitro safety. • Repeated oral dosing produced substantial accumulation of CBD and its metabolites (7-COOH-CBD, 7-OH-CBD, 6-OH-CBD) by day 21, with plasma CBD exposure increasing approximately 2.7-fold (AUCINF_D 567 versus 209 h·kg·ng/mL/mg), plasma half-life extending from 5.9 to 41.9 hours, and steady-state achieved by day 6. • Tissue analysis revealed marked CBD accumulation in adipose tissue (70,124 ng/g, 1,470-fold relative to plasma) and mesenteric lymph nodes (10,018 ng/g, 201-fold relative to plasma), with the metabolite 7-OH-CBD also accumulating in adipose tissue (42 ng/g, 21-fold relative to plasma) and lymph nodes (136 ng/g, 73-fold relative to plasma). **Dosage & Administration** Synthesized CBD was administered orally at 26.5 mg/kg once daily for 21 days in rats. In vitro studies used two synthesized CBD brands and two plant-derived CBD sources (high-purity isolate and lower-purity distillate). **Safety & Adverse Effects** No adverse effects were reported. All CBD samples demonstrated no genotoxicity, mutagenicity, or clinically significant hepatotoxicity in vitro. **Evidence Quality** This preclinical study provides moderate evidence with notable limitations: animal model (rats) findings may not directly translate to humans, single in vivo CBD source tested despite multiple in vitro comparisons, and lack of clinical safety correlation. Strengths include rigorous comparative methodology, sensitive analytical techniques, and comprehensive metabolite tracking. Results support further human studies examining accumulation dynamics with repeated CBD dosing.

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