Dimebon, a drug previously approved in Russia as a nonselective antihistamine and subsequently removed from the market, may be effective for the treatment of Alzheimer’s disease, according to a study in the July 19 Lancet. Rachelle S. Doody, MD, PhD, and colleagues reported that patients who received dimebon showed statistically significant improvement in five key aspects of Alzheimer’s disease—memory, cognition, activities of daily living, behavior, and global functioning.
The researchers randomly assigned 183 patients with mild to moderate Alzheimer’s disease from 11 sites in Russia to oral dimebon (10 mg three times daily for the first seven days, followed by 20 mg three times daily) or placebo for 26 weeks. The primary outcome was cognition, as measured by the 11-item Alzheimer’s Disease Assessment Scale–Cognitive subscale (ADAS-Cog).
Secondary outcomes included cognition, as measured by the Mini-Mental State Examination; behavior, as measured by the Neuropsychiatric Inventory; self-care and function, as measured by the Alzheimer’s Disease Cooperative Study–Activities of Daily Living; and impression of change, as measured by the Clinician’s Interview-based Impression of Change plus Caregiver Input.
A total of 155 patients completed the trial (78 with dimebon and 77 with placebo). At week 26, mean changes from baseline scores on all five outcome measures significantly favored dimebon. Significant improvements were seen in ADAS-Cog scores in the dimebon group, compared with the placebo group (mean change from baseline, -1.9 and 2.1, respectively; mean drug-placebo difference, -4.0).
Of the 155 patients who completed 26 weeks of therapy, 120 completed a six-month blinded extension trial, in which patients remained in their assigned groups. At week 52, patients who received dimebon showed significant improvements on all five outcome measures, compared with those who received placebo, said Dr. Doody and colleagues. Dimebon was well tolerated, with dry mouth and depression as the most commonly reported adverse events. ADAS-Cog scores improved by 1.2 points among patients receiving dimebon and worsened by 5.6 points among those taking placebo (mean drug-placebo difference, -6.9).
“In this study, dimebon improved the clinical course of Alzheimer’s disease, which is important given that the natural course is progressive deterioration over time,” said Dr. Doody, Professor of Neurology and Effie Marie Cain Chair in Alzheimer’s Disease Research at Baylor College of Medicine, Houston.
—Karen L. Spittler