Pharmacokinetics of a rivastigmine transdermal patch formulation in healthy volunteers: relative effects of body site application

A patch formulation of rivastigmine, an inhibitor of acetylcholinesterase and butyrylcholinesterase, is under development. The current objective was to evaluate the pharmacokinetic profile and patch adhesiveness following application at the upper back, chest, abdomen, thigh, and upper arm. In a single-dose, open-label, crossover study with 40 (42.5% men) healthy subjects, a 10-cm(2) patch containing 18 mg rivastigmine was applied to each body site. Median t(max) was 16 hours for all sites except the thigh (22 hours). Exposure levels and C(max) were highest at the upper back, chest, and upper arm sites. Adhesiveness was greatest when applied to the thigh, followed by the abdomen, upper arm, chest, and upper back, although no statistically significant correlations with pharmacokinetic parameters were found, except at the chest (P=.02). Pharmacokinetic profiles and adhesiveness of the upper back, chest, and upper arm, coupled with low rates of erythema at these sites, suggest their suitability for clinical use.