Background: Cannabidiol (CBD), a non-psychoactive compound in cannabis, has various pharmacological advantages associated with clinical use, especially for reducing inflammatory arthritis and paw edema in animal models. This study evaluated the anti-inflammatory effects of various oral CBD doses (5-40 mg/kg) in rats after injecting 0.1 mL of carrageenan. Methods: Rats were orally administered various CBD doses an hour before the carrageenan-induced inflammation to observe the anti-inflammatory effects of CBD. Paw edema was measured at 0, 1, 2, 3, 4, and 5 h after carrageenan induction. Following a six-hour induction of carrageenan, histological analysis employing hematoxylin and eosin staining was performed to investigate inflammatory cell infiltration at paw edema. In addition, blood samples were taken and used for cytokine detection using ELISA and bead-base assays. Results: We found that the efficacy of all oral CBD doses decreased paw edema and was comparable to or had greater efficacy than an anti-inflammatory agent (Diclofenac 10 mg/kg), especially at 2, 3, 4, and 5 h after induced paw edema. Moreover, a high dose (40 mg/kg) of CBD suppressed chemokine productions, including monocyte chemoattractant protein (MCP)-1 and MCP-3, compared to diclofenac and placebo. In addition, serotonin levels, a pro-inflammatory-like neurotransmitter, were drastically decreased in rats treated with either CBD or diclofenac. Conclusions: Oral CBD is an interesting anti-inflammatory agent for use in the clinical setting. However, more information regarding drug safety and efficacy in a large population of human studies is needed.
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