Dimebolin is an orally-available antihistamine drug with a long history of clinical use in Russia [1][2][3][4].

Dimebolin has been proposed to be useful for treating neurodegenerative disorders, including Alzheimer's disease (AD) and Huntington's disease (HD). Dimebon might exhibit efficacy by blocking NMDA receptors or voltage-gated Ca2+ channels and by preventing mitochondrial permeability pore transition [3].

Dimebolin is an orally-available antihistamine drug. Dimebon improved survival of cerebellar granule cells during long-term incubation with Aβ25-35. Dimebolin also blocked potential-dependent Ca(2+) entry into neurons by about 20% by blocking L-type Ca(2+) channels [4]. In the cerebellum cell culture, Dimebolin protected neurons against the neurotoxic action of Aβ25-35 with EC50 value of 25 μM. On isolated rat ileum intestine, Dimebolin displayed Ca2+-blocking properties with IC50 value of 57 μM. Dimebon also exhibited anticholinesterase activity with IC50 values of 7.9 μM and 42 μM for butyryl-choline esterase and acetylcholine esterase, respectively [5].

In rats treated with the neurotoxin AF64A, Dimebolin exhibited cognition and memory-enhancing properties. In mice, Dimebolin prevented NMDA-induced seizures with EC50 value of 42 ± 6 mg/kg [5].

References:
[1].  Lermontova NN, Lukoyanov NV, Serkova TP, et al. Dimebon improves learning in animals with experimental Alzheimer's disease. Bull Exp Biol Med. 2000 Jun;129(6):544-6.
[2].  Doody RS, Gavrilova SI, Sano M, et al. Effect of dimebon on cognition, activities of daily living, behaviour, and global function in patients with mild-to-moderate Alzheimer's disease: a randomised, double-blind, placebo-controlled study. Lancet. 2008 Jul 19;372(9634):207-15.
[3].  Wu J, Li Q, Bezprozvanny I. Evaluation of Dimebon in cellular model of Huntington's disease. Mol Neurodegener. 2008 Oct 21;3:15.
[4].  Lermontova NN, Redkozubov AE, Shevtsova EF, et al. Dimebon and tacrine inhibit neurotoxic action of beta-amyloid in culture and block L-type Ca(2+) channels. Bull Exp Biol Med. 2001 Nov;132(5):1079-83.
[5].  Bachurin S, Bukatina E, Lermontova N, et al. Antihistamine agent Dimebon as a novel neuroprotector and a cognition enhancer. Ann N Y Acad Sci. 2001 Jun;939:425-35.