Cannabidiolic Acid: Potential Role in Hyperalgesia and Inflammation
Many studies have proven that cannabinoids are effective pain killers. Additionally, patients cite pain relief as the top reason for their use of medical cannabis. This pain may be acute, chronic, or associated with other conditions like inflammation. In fact, increased pain — or hyperalgesia — is a common symptom of inflammatory conditions.
To determine the effects of different cannabinoids on hyperalgesia, researchers have utilized pre-clinical models of pain sensitivity. In these models, pain is induced via injection of a noxious substance like carrageenan into the paws of mice, which causes swelling and increased sensitivity to heat. Paw withdrawal to heat, as well as magnitude of swelling, can be used to measure treatment effects.
Studies have indicated that both tetrahydrocannabiol (THC) and cannabidiol (CBD) possess anti-hyperalgesia and inflammatory properties using similar pain sensitivity models. However, some evidence has also shown that cannabidiolic acid
(CBDA), the precursor molecule in the pathway to forming CBD, may be more effective than CBD itself.
Thus, researchers from the University of Guelph in Canada decided to comparatively evaluate the effects of CBDA, CBD, and THC on a model of hyperalgesia and inflammation.
CBDA treatment prior to carrageenan resulted in dose-dependent reductions in hyperalgesia and inflammation compared to CBD, which did not have the same effect at an equivalent low dose. THC however also reduced hyperalgesia and inflammation — but THC appeared to exert its effects through a cannabinoid 1 receptor mechanism, while CBDA worked through the transient receptor potential cation channel subfamily V member 1, or TRPV1. Low doses of THC and CBDA together also produced beneficial effects.
While these results are promising, this pre-clinical evidence must be confirmed in additional future studies.
Rock, E.M., et al., “Effect of Cannabidiolic Acid and Δ9-tetrahydrocannabinol
on Carrageenan-induced Hyperalgesia and Edema in a Rodent Model of Inflammatory Pain.” Psychopharmacology, vol.235, 2018, pp. 3259-3271.