Rivastigmine transdermal patch and capsule in Alzheimer's disease: influence of disease stage on response to therapy.

Objectives: The cholinesterase inhibitor rivastigmine is approved for the symptomatic treatment of mild to moderate Alzheimer's disease (AD). This exploratory, hypothesis-forming analysis assessed response to rivastigmine according to severity of dementia at baseline.

Methods: This was a retrospective analysis of a large randomized, placebo-controlled trial (ENA713D2320). AD patients treated with 9.5 mg/24 h rivastigmine patch, 17.4 mg/24 h rivastigmine patch, rivastigmine capsule (12 mg/day), or placebo were stratified according to baseline Mini-Mental State Examination (MMSE) scores: ≥7 to ≤12 (severe disease), ≥13 to ≤15 (moderately severe), ≥16 to ≤18 (moderate), or ≥19 to ≤25 (mild to moderate). Changes from baseline at Week 24 on Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), Alzheimer's Disease Cooperative Study-Clinical Global Impression of Change (ADCS-CGIC), and Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL) were assessed.

Results: Based on baseline MMSE scores, 141, 228, 333, and 348 patients had severe, moderately severe, moderate, and mild to moderate dementia. Worsening of ADAS-cog, ADCS-CGIC, and ADCS-ADL scores in patients receiving placebo were greater in patients with more severe dementia. Significant improvements versus placebo were seen with rivastigmine patch and/or capsule on ADAS-cog, ADCS-CGIC, and ADCS-ADL scores in patients with severe, moderately severe, and moderate AD (all p < 0.05). However, no significant improvements were seen in rivastigmine-treated patients with mild to moderate AD.

Conclusions: Rivastigmine benefits AD patients across dementia stages. Similar to previous cholinesterase inhibitor studies, greatest treatment effects with rivastigmine patch and capsule were seen in patients with more advanced dementia, most likely driven by greater placebo decline in this population.