Cannabidiol is the major nonpsychoactive ingredient in cannabis. Cannabidiol demonstrates a range of effects that may be therapeutically useful, including anti-seizure, antioxidant, neuroprotective, anti-inflammatory, analgesic, anti-tumor, anti-psychotic, and anti-anxiety properties. Exact mechanism of action of cannabidiol is not known, but may include effects on the orphan G-protein-coupled receptor GPR55; the transient receptor potential of vanilloid type-1 channel; the 5-HT1a receptor; and the α3 glycine receptors. GW Pharmaceuticals successfully developed the world’s first prescription medicine derived from the cannabis plant, Sativex® (buccal spray containing delta-9-tetrahydrocannabinol and cannabidiol) now approved in over 29 countries outside of the United States for the treatment of spasticity due to Multiple Sclerosis. GW Pharmaceuticals is developing Epidiolex® (a liquid formulation of pure plant-derived cannabidiol) for certain rare and severe early-onset, drug-resistant epilepsy syndromes.

NSI-189 is a novel oral drug which was developed by Neuralstem for the treatment of cognitive disorders. Now the drug is being tested in phase II of clinical trials in patients suffering from major depressive disorder. The mechanism of NSI-189 action is explained by its ability to stimulate the generation of new neurons in the hippocampus, however the exact target molecule is still unknown.

Gaboxadol (or THIP) is a direct GABA mimetic ligand at delta-containing receptors. Gaboxadol went into human clinical trials to test if the drug promoted sleep. It was generally well tolerated. Gaboxadol enhances delta power in NREM sleep in humans. Gaboxadol failed in Phase III for sleep studies. The side effects of Gaboxadol have been described as mild and similar in quality to those of other GABA-mimetics. Gaboxadol is in development with Ovid Therapeutics as a treatment for Angelman syndrome, fragile X syndrome and epilepsy.