Pharmacokinetic Evaluation of a Cannabidiol Supplement in Horses

• Published in: Journal of equine veterinary science Vol. 110; p. 103842
• Main Authors: Williams, Megan R., Holbrook, Todd C., Maxwell, Lara, Croft, Cara H., Ientile, Michelle M., Cliburn, Kacey
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2022
• Subjects: Administration, Oral; Animals; Cannabidiol; CBD; Chromatography, Liquid - veterinary; Cross-Over Studies; Equine; Horses; Pharmacokinetics; Tandem Mass Spectrometry - veterinary; Cannabidiol; Equine; CBD; Pharmacokinetics
• ISSN: 0737-0806; 1542-7412
• DOI: 10.1016/j.jevs.2021.103842

Cannabidiol (CBD) products have gained popularity among horse owners despite limited evidence regarding pharmacokinetics. The purpose of this study was to describe the pharmacokinetic profile of multiple doses of an orally administered cannabidiol product formulated specifically for horses. A randomized 2-way crossover design was used. Seven horses received 0.35 or 2.0 mg/kg CBD per os every 24 hours for 7 total doses, separated by a 2-week washout. Plasma CBD and delta-9-tetrahydrocannabinol (THC) were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) daily through day 10, then on day 14 after beginning CBD administration. On the final day of CBD administration, plasma CBD and THC were quantified at multiple times. After administration of 0.35 mg/kg of CBD, the Cmax of CBD was 6.6 ± 2.1 ng/mL while Tmax was 1.8 ± 1.2 hour, whereas the Cmax for THC was 0.7 ± 0.6 ng/mL with a Tmax of 2.5 ± 1 hour. After administration of 2.0 mg/kg of CBD, the Cmax of CBD was 51 ± 14 ng/mL with a mean Tmax of 2.4 ± 1.1 hour and terminal phase half-life of 10.4 ± 6 hour, whereas the Cmax of THC was 7.5 ± 2.2 ng/mL with a Tmax of 2.9 ± 1.1 hour. Oral administration of a cannabidiol product at 0.35 mg/kg or 2.0 mg/kg once daily for 7 days was well-tolerated. Based on plasma CBD levels obtained, dose escalation trials in the horse evaluating clinical efficacy at higher mg/kg dose rates are indicated.
•Once daily dosing of CBD at 0.35 and 2.0 mg/kg in the horse was well-tolerated but may result in plasma levels insufficient to provide clinical results.•CBD appeared in plasma rapidly after oral administration and showed an initial rapid decline followed by a more prolonged terminal elimination phase half-life.•Measurable THC levels are detectable in plasma with administration of this CBD product, highlighting the need to educate veterinarians and horse owners administering cannabidiol to competitive horses.