A once-weekly transdermal patch delivers the most commonly prescribed treatment for Alzheimer's disease in a way that is biologically equivalent to taking the medication orally, according to preliminary pilot study results. Corium International conducted the bioequivalence (BE) pilot study on its lead product, Corplex, which delivers donepezil — the same active ingredient found in the orally administrated Aricept (donepezil hydrochloride) — through skin absorption. Corium's Corplex system was designed to enable efficient delivery across the skin (transdermal) of small therapeutic molecules. These transdermal patches can adhere to either wet or dry surfaces for an extended period of time. Because Corplex Donepezil uses the same active ingredient found in Aricept, Corium International is pursuing the U.S. Food and Drug Administration's bioequivalence-based development and regulatory pathway (Section 505(b)(2) New Drug Application). This FDA process takes into consideration previous safety and efficacy results of an already approved drug in deciding whether to approve a new treatment. To confirm this new therapy could deliver the therapeutic active compound as efficiently as Aricept, the company conducted a BE pilot study where they tested two Corplex Donepezil transdermal patches that differed only in size. Patients treated with Corplex Donepezil presented similar concentrations of the drug in their blood as those reported in patients treated with Aricept. The smaller patch formulation achieved the FDA’s