NEW YORK -- July 17, 2008 -- Dimebon significantly improves the clinical course of patients with mild to moderate Alzheimer's disease (AD) and demonstrates increasing benefits over 12 months, according to a study published in this week's Dementia Special Edition of The Lancet.
Recently, dimebon has been restudied for its ability to block neurologic pathways and has shown neuroprotective effects in models for AD and Huntington's disease.
Rachelle S. Doody, MD, Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, Houston, Texas, and colleagues did a randomised, controlled trial to test the safety, tolerability, and efficacy of dimebon in treating mild to moderate AD.
The study included 183 patients with mild to moderate AD at 11 sites in Russia. All patients had a score on the Mini-Mental State Examination (MMSE) of 10 to 24.
Patients were randomised to dimebon 20 mg TID (n = 89) or placebo (n = 94). No other antidementia drugs were allowed. Patients were assessed over 6 months using the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) and 4 other secondary measures.
Of the patients, 78 (88%) from the dimebon group and 77 (82%) from the placebo group completed the double-blind study.
After the 6 months, 134 patients entered the subsequent 6-month blinded part of the study, during which they stayed on dimebon or placebo, but neither patients nor investigators knew which treatment patients were taking. Of these patients, 120 completed the extension phase.
The researchers found that treatment with dimebon gave significant improvements in ADAS-Cog compared with placebo, with a mean difference of 4 points on the scale between the 2 groups.
The benefits seen reflected both significant improvement compared with baseline (1.9 points on ADAS-Cog) for patients given dimebon, as well as significant decline in those who received placebo. The benefit at the end of the extension study had increased to 6.9 points on ADAS-Cog.
Dry mouth and depression were the most common adverse events related to dimebon, but proportions of other adverse events were similar between both groups.
"[Our] study of patients with mild to moderate Alzheimer's disease has shown that patients given dimebon were significantly improved compared with baseline, and compared with those taking placebo, for all 5 outcome measures," the authors wrote. "These outcome measures included assessment of cognition, function, and behaviour.
"The continued and increasing benefit of dimebon over the course of this study is especially important because, at present, no approved therapies for mild to moderate Alzheimer's disease have shown increasing improvement over 12 months."
In an accompanying comment, Alistair Burns, MD, Psychiatry Research Group, University of Manchester, Manchester, United Kingdom, and Prof. Robin Jacoby, Department of Psychiatry, University of Oxford, Oxford, United Kingdom, said that the "addition of treatment options is good news for patients and clinicians. It promotes choice and offers the possibility of bespoke [customised] treatment packages which maximise the chances of response."
"Further work will establish its efficacy (or otherwise) in addition to, or compared with, established treatments, and indeed a second phase 3 trial has recently been announced," the researchers said.
SOURCE: The Lancet
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