Adding Memantine to Rivastigmine Therapy in Patients With Mild-to-Moderate Alzheimer's Disease: Results of a 12-Week, Open-Label Pilot Study

Objective: At present, inhibition of cholinesterase is the treatment of choice for subjects with mild-to-moderate Alzheimer’s disease (AD). Memantine, a noncompetitive antagonist at N-methyl-d-aspartate receptors, is currently used to treat subjects with moderate-to-severe AD. The goal of this multicenter, open-label pilot study was to investigate whether combination therapy with memantine added to rivastigmine is safe and beneficial in subjects with mild-to-moderate AD.

Method: Patients with a DSM-IV diagnosis of dementia of the Alzheimer’s type (N = 95), who were treated with rivastigmine (6-12 mg/day) for a maximum duration of 24 weeks prior to baseline, received memantine (5-20 mg/day) in combination with rivastigmine for 12 weeks. The primary efficacy variable was the change in the Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) total score at the end of 12 weeks compared with baseline. The study was conducted between September 15, 2003, and May 27, 2004.

Results: There was a statistically significant difference between baseline and week 12 for the ADAS-cog total score, showing a positive effect of combination therapy. Combination therapy did not evidence any unexpected safety concerns and was well-tolerated by most patients.

Conclusion: Memantine in combination with rivastigmine appears to be safe and beneficial in patients with mild-to-moderate AD. Our results need to be confirmed in a large, long-term, randomized, double-blind, placebo-controlled clinical trial.