Detection time following administration of cannabidiol applied as an oral emulsified solution in Thoroughbred horses

Cannabidiol (CBD) is now classified as a controlled medication by the International Equestrian Federation and Horse Racing Integrity and Safety Authority, therefore detection and withdrawal times are meaningful for use in competition horse exercise recovery. This study aimed to determine the detection time of CBD and its main metabolites, 7-hydroxy-cannabidiol (7-OH-CBD) and 7-carboxy-cannabidiol (7-COOH-CBD) after 2 doses of a CBD solution. The solution was a 4 mL oral emulsified solution that contained 250 mg of CBD in a medium of organic coconut oil. A convenience sample of 8 healthy Thoroughbred horses with a mean age of 3.6 ± 1.5 years and weight of 446.0 ± 16.2 kg was used. Horses maintained their normal daily training to replicate practical use in competition horses. A detailed physical exam was performed by a veterinarian on d 1 before the first administration of the solution. Horses received the first administration of CBD at 18:00h on d 1, followed by the second administration at 06:00h on d 2 to mimic a post-competition recovery protocol. The dose was given orally by syringe under the horses’ tongue. Blood samples were collected on d 1–10 from the jugular vein. Urine samples were collected on d 7 by free catch. Concentrations of CBD and each metabolite were measured using liquid chromatographyand tandem mass spectrometry (LC-MS/MS) in an analytical pharmacology laboratory. Descriptive statistical analysis was completed using R version 4.2.2. The limit of quantitation (LoQ) of CBD is 0.10 ng/mL in serum and 0.25 ng/mL in urine. The LoQ of 7-OH-CBD and 7-COOH-CBD is 0.10 ng/mL in both serum and urine. On d 7, serum CBD was 0.054 ± 0.03 ng/mL, serum 7-COOH-CBD was 3.525 ± 2.28 ng/mL, and serum 7-OH-CBD was not detected after d 1. On d 10, serum CBD was 0.041 ± 0.02 ng/mL and serum 7-COOH-CBD was 0.788 ± 0.56 ng/mL.On d 7, urine CBD was 0.013 ± 0.02 ng/mL and urine 7-OH-CBD was 0.083 ± 0.01 ng/mL. Concentrations of 7-COOH-CBD were not detected in the urine on d 7. Due to the variability in cannabinoid products, these results may be specific to this product formulation. Variables that will cause differences in clearance time include the manufacturing process, pellets or oil formulation, emulsion process, dose, and method of absorption. All 3 compounds had concentrations below the urinary LoQ and therefore not quantifiable in urine on d 7. Serum CBD was not quantifiable after d 7, serum 7-CBD-COOH was quantifiable on d 10, and serum 7-OH-CBD was not detectable after d 1.

Source: https://doi.org/10.1016/j.jevs.2023.104315