Cannabinoids have been used in Eastern medicine for many years as pain relievers. Δ⁹-tetrahydrocannabinol (THC), the major psychoactive compound in marijuana and hashish, has been shown to interact with two specific cannabinoid receptors: cannabinoid receptor 1 (CB1 Receptor or CB1R) and cannabinoid receptor 2 (CB2 Receptor or CB2R). The cannabinoid receptors can be distinguished by their amino acid sequences, signaling mechanisms, and tissue distributions. Both receptors belong to the G-protein-coupled receptor (GPCR) superfamily.