Pharmacokinetic Evaluation of a Cannabidiol Supplement in Horses.
Authors: Williams Megan R, Holbrook Todd C, Maxwell Lara, Croft Cara H, Ientile Michelle M, Cliburn Kacey
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Cannabidiol Pharmacokinetics in Horses With CBD products increasingly appearing in equine supplement catalogues, Williams and colleagues have provided the first detailed pharmacokinetic characterisation of an equine-formulated oral cannabidiol product, addressing a significant evidence gap in a category many horse owners are already purchasing. Seven horses received either 0.35 or 2.0 mg/kg CBD daily for seven consecutive days in a randomised crossover design, with plasma concentrations of both CBD and THC quantified using liquid chromatography-tandem mass spectrometry through day 10 and again on day 14. The low dose (0.35 mg/kg) produced peak plasma CBD concentrations of 6.6 ± 2.1 ng/mL within 1.8 hours, whilst the five-fold higher dose (2.0 mg/kg) achieved substantially greater Cmax values of 51 ± 14 ng/mL with a terminal half-life of approximately 10.4 hours; importantly, THC concentrations remained minimal even at the higher dose (7.5 ± 2.2 ng/mL), and both regimens were well tolerated. These findings provide practitioners with baseline pharmacokinetic data to contextualise CBD supplementation in their clinical thinking, though the authors note that substantially higher dose escalation studies are necessary to establish whether these plasma levels translate to meaningful clinical efficacy in horses with conditions such as anxiety, pain, or inflammatory disorders.
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Practical Takeaways
- •CBD supplements formulated for horses show dose-dependent pharmacokinetic profiles with peak plasma levels occurring 2-3 hours post-administration and measurable levels persisting to day 14
- •Both tested doses (0.35 and 2.0 mg/kg) were well-tolerated, suggesting safety margin exists, but clinical efficacy data is still lacking and required before recommending to clients
- •Current evidence is insufficient to guide practitioners on appropriate CBD dosing for therapeutic purposes; await results from higher-dose efficacy trials before incorporating into practice recommendations
Key Findings
- •At 0.35 mg/kg CBD, plasma Cmax was 6.6 ± 2.1 ng/mL with Tmax of 1.8 ± 1.2 hours; THC Cmax was 0.7 ± 0.6 ng/mL
- •At 2.0 mg/kg CBD, plasma Cmax was 51 ± 14 ng/mL with Tmax of 2.4 ± 1.1 hours and terminal half-life of 10.4 ± 6 hours; THC Cmax was 7.5 ± 2.2 ng/mL
- •Oral CBD administration at both dose rates (0.35 and 2.0 mg/kg once daily for 7 days) was well-tolerated in horses
- •Study establishes preliminary pharmacokinetic data supporting need for higher dose escalation trials to evaluate clinical efficacy