Evaluating The Safety Of Donepezil Hydrochloride (Aricept) For Up To 1 Year In The Treatment Of The Cognitive Dysfunction Exhibited By Children With Down Syndrome - Follow-Up To A 10-Week, Double-Blind, Placebo-Controlled Trial

An Open-label Study to Evaluate the Safety of Donepezil Hydrochloride((Aricept®) for up to 1 Year in the Treatment of Cognitive Dysfunction Exhibited by Children With Down Syndrome-Follow-up to a 10-Week,Double-Blind,Placebo-Controlled Trial

The purpose of this study is to determine the safety of donepezil hydrochloride (Aricept) in children with Down syndrome who have finished the preceding 10-week, double-blind study of donepezil hydrochloride. Medical tests for drug safety will be conducted at each clinic visit.

All children in this study will take donepezil hydrochloride once a day, and will come back to the clinic at 8, 24 and 42 weeks after the study has begun. In between these clinic visits, the clinical staff will telephone the child's parent or caregiver to discuss drug safety observations and possible changes in drug dose. At the end of the study (42 weeks), psychological testing will also be given to determine how well the child is functioning.

Inclusion Criteria:

• Diagnosis of Down syndrome (established during study E2020-A001-220).
• Completion of study E2020-A001-219 (NCT00570128 [also known as A2501059]) with no ongoing seroius adverse events and no severe drug reactions.

Exclusion Criteria:

• Weight less than 20 kg.
• Clinically significant conditions affecting absorption, distribution or metabolism of the study medication.
• No reliable parent or caregiver, or unwillingness or inability of parent or caregiver to fulfill the requirements of the study.
• Females of childbearing potential who are not practicing an effective means of birth control.