Aricept

Analyst Outlook

Aricept (donepezil; Eisai/Pfizer) has been the gold standard in the treatment of all stages of
Alzheimer’s disease for more than a decade. However, the drug’s loss of exclusivity in the major
markets between 2010 and 2013 has sparked a decline in sales. In 2009, Pfizer’s and Eisai’s Aricept
revenues peaked at $4.5bn, and then gradually declined to $621m in 2014. A lifecycle management
strategy employed by Eisai – the launch of a sustained-release 23mg dose – may have been initiated
too late and did little to lessen the impact of generic erosion. As such, generic donepezil is left as the
comparator therapy that all new Alzheimer’s disease market entrants must seek to improve upon in
order to achieve commercial success.

Drug Overview

Aricept was originally developed by Eisai and is indicated for the treatment of mild, moderate, and
severe Alzheimer’s disease. Various formulations are now available, including 5mg, 10mg, and 23mg
oral tablets, orally disintegrating tablets, and an oral jelly for those with difficulty swallowing. The
5mg and 10mg tablets are typically used for mild to moderate Alzheimer’s disease, while the recently
approved 23mg sustained-release dose is indicated for moderate to severe Alzheimer’s disease.
As an acetylcholinesterase (AChE) inhibitor, Aricept blocks acetylcholine degradation, thereby
increasing cholinergic transmission. This mechanism, which is otherwise deficient in patients with
Alzheimer’s disease, provides symptomatic relief to patients (Bartus, 2000).