Aim:  The cholinesterase inhibitor rivastigmine is available in both oral and transdermal forms. The efficacy of oral rivastigmine appears to be dose-dependent. The current analysis investigates the effect of dose on the efficacy of the rivastigmine transdermal patch.

Methods:  This was a retrospective analysis of a large, international, 24-week, randomised, placebo- and active-controlled trial (IDEAL, CENA713D2320) of rivastigmine in patients with mild-to-moderate Alzheimer’s disease (AD). Patients received the 9.5 mg/24 h rivastigmine patch, the 17.4 mg/24 h rivastigmine patch, 12 mg/day rivastigmine capsules or placebo. Changes from baseline at week 24 on the AD Assessment Scale–cognitive subscale (ADAS-cog), AD Cooperative Study–Clinical Global Impression of Change (ADCS-CGIC) and the AD Cooperative Study–Activities of Daily Living (ADCS-ADL) scale were calculated based on the patient’s mode and last prescribed patch dose. The analysis included the 4.6 mg/24 h and 13.3 mg/24 h patch doses, for which efficacy data have not previously been reported.

Results:  Significant differences (p < 0.05 vs. placebo) were seen on the ADAS-cog and ADCS-ADL for all mode rivastigmine patch doses (except 4.6 mg/24 h) and all last prescribed rivastigmine patch doses (except 4.6 mg/24 h and 13.3 mg/24 h). Patients with a last prescribed/mode patch dose of 9.5 mg/24 h and 13.3 mg/24 h showed significant improvements (p < 0.05 vs. placebo) on the ADCS-CGIC.

Conclusion:  Rivastigmine patch doses higher than 9.5 mg/24 h may offer additional benefits. The 13.3 mg/24 h patch is worthy of further investigation.