Rivastigmine Transdermal Patch Skin Tolerability Results of a 1-Year Clinical Trial in Patients with Mild-to-Moderate Alzheimer's Disease

Background and Objectives: Transdermal patches provide non-invasive, continuous drug delivery, and offer significant potential advantages over oral treatments. With all transdermal treatments a proportion of patients will experience some form of skin reaction. The rivastigmine patch has been approved for the treatment of mild-to-moderate Alzheimer's disease (AD) since July 2007 in the US. The aim of the component of the trial reported here was to evaluate the skin tolerability of the rivastigmine transdermal patch in patients with mild-to-moderate AD. Methods: The pivotal IDEAL trial was a 24-week, randomized, double-blind, placebo-controlled, multicentre trial of the efficacy and tolerability of the rivastigmine transdermal patch in 1195 patients with mild-to-moderate AD. This was followed by a 28-week open-label extension. Although not prospectively defined as a secondary assessment, during both phases of the study the condition of the patients' skin at the application site was evaluated. These data are reviewed in this article. Results: During the 24-week, double-blind phase of the study, 89.6% of patients in the target 9.5 mg/24 h patch treatment group had recorded 'no, slight or mild' signs or symptoms for their most severe application-site reaction. Erythema and pruritus were the most commonly reported reactions. No patient in any patch treatment group experienced a skin reaction that was reported as a serious adverse event. In the 9.5 mg/24 h treatment group, 2.4% of patients discontinued treatment due to an application-site reaction. During the 28-week open-label extension, the skin tolerability profile was similar to that seen in the double-blind phase. Overall, 3.7% of patients discontinued treatment due to application-site skin reactions. There was no indication that the severity of the skin reactions increased over time. Conclusion: Overall, the data support a favourable skin tolerability profile for the rivastigmine transdermal patch, and provide reassurance that the benefits of rivastigmine patch therapy for patients with AD are not confounded by significant skin irritation problems. Nevertheless, care should be taken to follow manufacturer's advice about patch application, such as daily rotation of the application site, to minimize the risk of skin reactions.