Antihistamine Agent Dimebon As a Novel Neuroprotector and a Cognition Enhancer


Address for correspondence: Sergey O. Sablin, Ph.D., Selena Pharmaceuticals, Inc., 167 Skyview Way, San Francisco, CA 94131, U.S.A. Voice: 415-990-4761; fax: 415-750-6959.


Abstract: Dimebon, launched earlier in Russia as an antihistamine drug, was evaluated as a representative of a new generation of anti-Alzheimer's drugs that have two beneficial actions: (1) to alleviate symptoms, and (2) to prevent progression of the disease. The drug demonstrated cognition and memory-enhancing properties in the active avoidance test in rats treated with the neurotoxin AF64A, which selectively destroys cholinergic neurons. Dimebon protected neurons in the cerebellum cell culture against the neurotoxic action of β-amyloid fragment (Aβ25−35, EC50= 25 μM). In vitro, Dimebon displayed Ca2+-blocking properties (IC50= 57 μM, on isolated rat ileum intestine) and pronounced anticholinesterase activity (IC50= 7.9 μM and 42 μM for butyrylcholine esterase and acetylcholine esterase, respectively). It also exhibited strong anti-NMDA activity in the prevention of NMDA-induced seizures in mice (EC50= 42 ± 6 mg/kg i.p.). A beneficial effect of Dimebon in the therapy of Alzheimer's disease was demonstrated in a pilot clinical trial performed in the Moscow Center of Gerontology. Fourteen patients who participated in the trial were evaluated for their state of personality and for the severity of the disease. The evaluation included orientation (space, place, time, and patient personality), memory for the past and present, life in present, speech, irritability, and so forth. During and after the eight-week therapy with Dimebon, cognitive and self-service functions of patients improved significantly, and psychopathic symptoms, anxiety, depression, tearfulness, and headache were substantially diminished. The results of these studies suggest Dimebon as a new candidate for the therapy of Alzheimer's-like disorders.