Apimostinel
Apimostinel is an antidepressant, acting as a selective partial agonist of an allosteric site of the glycine site of the NMDA receptor complex, which is under investigation by Naurex and Allergan for the treatment of major depressive disorder. As of 2015, an intravenous formulation of apimostinel is in a phase II clinical trial for MDD, and an oral formulation is concurrently in phase I trials for MDD.
Its mechanism of action and effects are similar to those of rapastinel, which is under development as an adjunctive therapy for treatment-resistant depression also by Naurex. However, apimostinel is 100-fold more potent by weight and, whereas rapastinel must be administered via intravenous injection, is orally-active. Apimostinel is intended by Naurex as an improved, follow-up drug to rapastinel. Similarly to rapastinel, apimostinel is an amidated tetrapeptide, and has almost an identical chemical structure to rapastinel, but has been structurally modified via the addition of a benzyl group. The drug has shown rapid antidepressant effects in pre-clinical models of depression. In addition, similarly to rapastinel, it is well tolerated and lacks the schizophrenia-like psychotomimetic effects of other NMDA receptor antagonists such as ketamine.
Commercial competitors of apimostinel include AV-101 from VistaGen Therapeutics and Cerecor's CERC-301.CERC-301#cite note-8|
