Dimebon is an antihistamine that used to be popular in Russia before better alternatives became available. It is also a weak cholesterinase inhibitor, similar to certain drugs used to combat Alzheimer disease. A trial of Dimebon for mild-to-moderate Alzheimer disease found that patients treated for six months did significantly better on four separate measures of cognition, behaviour, and functioning than those given a matching placebo. Doctors' impressions of patients' progress were also significantly more favourable for those patients treated with Dimebon. Dry mouth and depression were the main side effects.
Lancet 2008: 372: 207-215