New approaches in the design and development of cannabinoid receptor ligands: multifunctional and bivalent compounds.

Since the identification of the endocannabinoid system, two G protein-coupled receptors (GPCRs) of this complex system were identified and characterized: cannabinoid receptors type 1 (CB1R) and type 2 (CB2R). In addition to orthosteric and subsequently allosteric ligands, new strategies have been used to target CBRs. Bivalent ligands and multifunctional ligands acting at diverse biological targets have been designed, synthesized, and characterized for both CBRs. Due to their altered receptor binding and pharmacological profiles, they are interesting tools to explore CBR functions and their interactions with other physiological systems. Moreover, this approach may bear therapeutic advantages in the therapy of CBR-related disorders, especially multifactorial diseases. Promising prospects include anorectics with fewer side effects, analgesics with decreased tolerance, and therapeutics with multiple pharmacological activities for the treatment of cancer, inflammation, multiple sclerosis, Huntington's and Alzheimer's diseases.