Effect of cannabidiol, cannabinol and tetrahydrocannabivarin in managing inflammatory pain

Current medications used to treat the inflammatory pain either have limited effectiveness or may be associated with serious side effects. Non-psychoactive phytocannabinoids may have a better safety profile and could be used as an alternative approach to treat this condition. The aim of this study was to test the potential of three phytocannabinoids, cannabinol (CBN), tetrahydrocannabivarin (THCV) and cannabidiol (CBD), in treating inflammatory pain. The inflammatory pain was triggered in male rats by a single intra-articular knee injection of the complete Freund's adjuvant (CFA). One week later, rats were given four daily administrations of ibuprofen, CBN, THCV or CBD. Our data demonstrated that CFA injection triggered an inflammatory response expressed as damage of the synovial tissue, reduced locomotor activity, increased mechanical and, to a lesser extent, thermal pain sensitivity, and loss of body weight. All phytocannabinoids reduced mechanical hyperalgesia and had no or a minor effect on locomotor activity. Treatment with CBN also lowered thermal hypersensitivity. Treatment with CBN and THCV recovered the body weight of CFA-injected rats. However, administration of CBD reduced body weight and elevated blood monocyte and granulocyte levels above those of the CFA-injected control animal group. We conclude that CBN and THCV may have potential in managing inflammatory pain.