Tolerability and efficacy of the long-term administration of memantine hydrochloride (Memary®) in patients with moderate to severe Alzheimer's disease

Abstract

Aim: Memantine hydrochloride (Memary®), launched in June 2011 in Japan, is used in patients with moderate to severe Alzheimer's disease. We performed an integrated analysis of data obtained from different clinical studies of memantine hydrochloride conducted between 2002 and 2011 in Japan in order to examine the long-term tolerability and efficacy of this drug at a dose of 20 mg/day. Methods: Using clinical studies of memantine hydrochloride performed in Japan between 2002 and 2011, the therapeutic safety and the time course of MMSE scores in 702 subjects who had received memantine hydrochloride were examined. Results: The mean duration of memantine treatment was 798.1 days, with the longest duration of 3,373 days (approximately nine years and two months). The incidence of adverse events every 52 weeks of treatment ranged from 71.0% to 88.9%, and the incidence of adverse drug reactions ranged from 5.6% to 32.1%, with no associations between the incidence of adverse events and the treatment duration. There were no adverse drug reactions specific to the long-term administration of this drug. The occurrence of "adverse events" was the primary reason for drug discontinuation. During the long-term study observation period, there were many cases of adverse events and treatment discontinuation due to the background factors of the subjects, including adverse events associated with aging and progression of the underlying conditions. In addition, treatment discontinuation was also associated with admission to a nursing home or facility due to changes in home nursing care. The degree of MMSE score reduction over time was lower in the patients treated with memantine than the expected MMSE score reduction observed in the untreated patients. Conclusions: Based on these findings, there are no issues regarding the tolerability of memantine hydrochloride administered at a dose of 20 mg/day over the long term. Considering changes in the MMSE score, the results indicated that memantine hydrochloride may inhibit worsening of the cognitive function for long periods of time in patients with Alzheimer's disease.