Dimebon (latrepirdine) is an orally available, small molecule, gamma carboline derivative that was developed and used in Russia as an over-the-counter oral antihistamine for allergy treatment since 1980s. In 1990s it was shown that Dimebon has promising potential in treating neurodegenerative diseases. In 2003, Medivation Inc acquired the rights to Dimebon. Medivation went public in December 2004, with Dimebon as the only drug in its pipeline. The product was being developed by Medivation and Pfizer as a treatment for early-stage Alzheimer's disease and Huntington's disease. However, development was discontinued by Medivation and Pfizer in early 2012. Dimebon inhibits alpha-Adrenergic receptors (alpha1A, alpha1B, alpha1D, and alpha2A), Histamine H1 and H2 receptors and Serotonin 5-HT2c, 5-HT5A, 5-HT6 receptors with high affinity. Dimebon may act by blocking NMDA receptors or voltage-gated Ca2+ channels and by preventing mitochondrial permeability pore transition.