This 2018 study aimed to investigate the pharmacokinetics of cannabidiol (CBD) in healthy dogs using three different formulations (oral microencapsulated oil beads, oral CBD-infused oil, and CBD-infused transdermal cream) at doses of 75mg or 150mg every 12 hours for six weeks. The study found that oral CBD-infused oil resulted in the higher systemic exposure out of the three delivery methods tested.
The exposure was dose-proportional, and oral CBD-infused oil provided the most favorable pharmacokinetic profile. Serial CBD plasma concentrations were measured over 12 hours and repeated at 2, 4, and 6 weeks, showing higher levels of systemic exposure with oral CBD-infused oil.
The use of CBD for medical purposes in both humans and animals has been growing in popularity in recent years. However, there is a lack of data on the pharmacokinetics of CBD in dogs. In an effort to address this, this study was conducted to investigate the pharmacokinetics of CBD in healthy dogs.
Thirty healthy adult male beagle dogs, from 4 to 5 years of age, were randomly assigned to 1 of 3 CBD delivery methods: CBD-infused transdermal cream, oral microencapsulated oil beads, or oral CBD-infused oil. The dogs were then divided into 2 different dosing groups to receive either 75 mg or 150 mg every 12 hours. All dogs were administered a total daily dose of either 150 or 300 mg of CBD using 1 of the following delivery methods: CBD-infused transdermal cream (110 mg/mL) applied to the pinnae; beads of microencapsulated oil in capsules (microencapsulated oil beads; 25-mg and 50-mg capsule sizes); or CBD-infused oil (75 mg/mL or 150 mg/mL). These doses corresponded with approximately 10 mg/kg body weight per day or 20 mg/kg body weight per day. For the duration of the study, all dogs were administered each dose of CBD after a small meal.
In the first part of the study, CBD plasma concentrations were measured during the initial 12 hours of dose administration. Blood samples were collected at nine time points, including before administration and up to 720 minutes after administration. In the second part of the study, all dogs continued to receive their respective dose and delivery method for a total of 6 weeks, with blood collected for CBD plasma concentrations at 2, 4, and 6 weeks after the first dose.
The researchers hypothesized that a transdermal route of administration would be more effective in delivering CBD due to its avoidance of first-pass effect from the liver, which typically reduces the bioavailability of orally administered CBD in both dogs and humans. However, in this study, it was demonstrated that the CBD-infused transdermal cream did not reach similar plasma concentrations as the other 2 oral formulations.
CBD-infused transdermal cream was applied to the pinnae of the dogs in this study, which are the floppy outer parts of the ear. This method did not lead to similar plasma concentrations of CBD compared to the oral CBD-infused oil or oral microencapsulated oil beads. This could be due to the thickness of the skin of the pinnae or the ability of the CBD-infused cream to be absorbed into the bloodstream. CBD is highly lipophilic, meaning it has an affinity for fats, and it can accumulate in the outer layer of skin called the stratum corneum without penetrating deeper layers of the skin. As a result, the transdermal cream may have been unable to penetrate the skin enough to provide the same level of CBD to the bloodstream as the other delivery methods.
Contrary to popular belief in the industry that microencapsulated or transdermal versions of CBD absorb better than regular oral CBD oil, this study provides scientific evidence that oral CBD oil is actually superior in absorption. This highlights the importance of conducting rigorous independent research and not relying solely on industry claims when making decisions about CBD products.
In conclusion, this study investigated the pharmacokinetics of CBD in healthy dogs using three different formulations: oral microencapsulated oil beads, oral CBD-infused oil, and CBD-infused transdermal cream. The results showed that the oral CBD-infused oil formulation provided the most favorable pharmacokinetic profile, with higher maximal concentrations and systemic exposure than the other two formulations. Additionally, the oil formulation had the smallest amount of inter-individual variability in plasma CBD concentrations. In contrast, the CBD-infused transdermal cream did not reach similar plasma concentrations as the other two formulations, likely due to diffusion barriers such as the thickness of the pinnae skin or the absorptivity of the cream. These findings suggest that the oral CBD-infused oil formulation is the most superior option for the best absorption of CBD for dogs. However, clinical trials are necessary to investigate further.
Study Title: Pharmacokinetics of cannabidiol administered by 3 delivery methods at 2 different dosages to healthy dogs
Study Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6038832