With the increase in the use of alternative treatments for people has come the same increase in horses. There is a lot of information out there and evidence of the benefits of using herbals for horses. Unfortunately there are few actual scientific studies. However, more and more are popping up and are having positive results for how the world of natural, preventative, holistic care is viewed.
In February 2018, the University of Veterinary Medicine conducted a study of the pharmacokinetics (study of absorption, distribution, metabolism and excretion) of harpagoside, the active ingredient in Devil’s Claw. Devil’s Claw has a long history of use as an anti-inflammatory and analgesic agent. It has been effective on symptoms of arthritis, muscle pain, headaches, improving digestion and rheumatic pain. In horses it has been found beneficial for degenerative disorders, inflammation, pain due to arthritis and muscle pain. In the most recent study, the researchers gathered information in order to design a dosing regimen of Devil’s Claw for horses as well as obtain additional information on the effects of Devil’s Claw on the equine.
Six, healthy, warm-blooded horses, without any history of joint issues, including 1 gelding and 5 mares, were selected for this study. They were given doses of harpagoside based on the recommended dose for humans while considering their body weight and mass. In trial one, each horse was given 5 mg of harpagoside. This was followed by a 7 day washout period and then for trial 2 each horse was given 10 mg of harpagoside. Blood samples were collected every half hour for the first 3 hours and then again at 4, 6, 8, 12 and 24 hour marks in each trial.
Plasma samples were analyzed. It was found that harpagoside was detected just 30 minutes after administration and reached maximum concentration in the plasma at one hour in both of the trials. It was absorbed quickly into the blood stream. Harpagoside continued to be detected through 9 hours after being administered, indicating it is metabolized to a low extent which lowers the risk of interaction with other drugs. Further, there were no signs of adverse reactions seen during the period of observation, including no gastro-intestinal issues.
So, what does all this mean? The Food and Drug Administration (FDA) has said that herbals should be tested for blood levels of active ingredients, representative markers and chemical compounds. The desirable clinical properties of an anti-inflammatory drug that can be used for long term treatment of osteoarthritis are: fast acting, efficient oral bioavailability, long duration of effects, sufficient therapeutic effect and few to no side effects or drug interactions. When you look at this study, the results indicate that harpagoside meets these properties.
The results can also be compared to human studies as both equine and human subjects reach maximal harpagoside concentration in plasma after 1 hour. The dosage was significantly higher in the equine study due to size but still reached maximum concentration at the same time. Appropriate dosing can be determined based on what we know about human dosing and the vast amount of studies proving its efficacy. According to the researchers, “Devil’s Claw is a safe drug and well-tolerated on oral administration route.” These results are important to understand the dosing and length of time Devil’s Claw is present and effective in the equine.
Pharmacokinetics of harpagoside in horses after intragastric administration of a Devil’s Claw (Harpagophytum procumbens) extract. Journal of Veterinary Pharmacology and Therapeutics, 2019