A 25-week, open-label trial investigating rivastigmine transdermal patches with concomitant memantine in mild-to-moderate Alzheimer's disease: a post hoc analysis

Objective: To investigate the tolerability and efficacy of the rivastigmine transdermal patch in patients with mild-tomoderate Alzheimer's disease receiving concomitant memantine. Research design and methods: Post hoc analysis of a 25-week, randomized, prospective, open-label, parallel-group study. Patients receiving donepezil were switched to rivastigmine patches (4.6 mg/24 h) immediately or following a 7-day withdrawal for 4 weeks (core phase), before titrating up to 9.5 mg/24 h for a further 20-week extension phase. Prior memantine therapy was continued throughout. Clinical trial registration: clinicaltrials.gov. NCT00428389. Main outcome measures: Tolerability (adverse events [AEs], serious AEs [SAEs] and discontinuations) and efficacy (cognition, global functioning and activities of daily living [ADLs]) were assessed for the rivastigmine transdermal patch, with or without concomitant memantine. Results: Overall, 135 and 126 patients received rivastigmine with and without memantine, respectively. Of these, 122 (90.4%) and 118 (93.7%) patients with and without memantine, respectively, completed the core phase; 120 and 114 patients, respectively, entered the extension phase, and 90 (75.0%) and 86 (75.4%) completed the study. The incidences of AEs (73.3 vs. 67.5%) and SAEs (10.4 vs. 7.1%) were both slightly larger in patients receiving concomitant memantine, but the differences were not statistically significant (95% CIs: -5.2, 16.9 and -3.6, 10.1 for AEs and SEAs, respectively). The incidence of gastrointestinal AEs was low in both groups. Discontinuation due to AEs was higher in patients who received memantine (17.0 vs. 11.9%). Changes in cognitive and global function were similar between groups. ADL scores worsened in both groups; significantly more in those treated with memantine. Conclusion: Use of the rivastigmine transdermal patch in patients on established memantine appears to be well-tolerated, with only modest, non-significant increases in AEs compared with monotherapy, and did not seem to affect cognition or global functioning adversely.