Objective: To assess the tolerability and efficacy of switching patients with probable Alzheimer’s disease (AD) from donepezil or rivastigmine to galantamine without a washout period.
Design: Sixteen patients receiving rivastigmine or donepezil but experiencing a decline in cognition, behavior, or activities of daily living were permitted to switch overnight to galantamine without washout in an effort to avoid further decline. Five patients began galantamine at 4 mg bid, 7 began at 8 mg bid, and 4 began at 12 mg bid. No other medication changes were made for at least 2 weeks.
Materials and methods: Cognition was assessed by the Mini-Mental Status Examination (MMSE) and behavior by the Neuropsychiatric Inventory (NPI). Caregivers were advised to record any adverse events and were telephoned within 2 weeks of the switch.
Results: The 16 patients consisted of 4 males and 12 females aged 66 to 90 years. Only 2 patients experienced side effects during the first week of treatment. One patient had transient nausea for several days after switching to galantamine from rivastigmine; galantamine was discontinued. The other patient had no complaints of nausea but had increased confusion after 2 weeks and therefore withdrew from the study. All but 2 patients showed stabilized or improved functional, cognitive, and behavioral status (compared with prior therapies) as measured by the MMSE and NPI at 3 and 6 months in comparison with baseline.
Conclusions: Galantamine offers further therapeutic options for AD patients whose symptoms worsen despite previous treatment with an acetylcholinesterase inhibitor. These data suggest that it is feasible to switch patients with probable AD from donepezil or rivastigmine to galantamine without washout, if the reason for switching is lack of efficacy and the patient is tolerating the current therapy well; the changeover to a therapeutically effective dose of galantamine was well tolerated, and no withdrawal effect was noted. Only one patient experienced symptoms of cholinergic toxicity; these were mild and transient. Most patients had cognitive or behavioral improvement or both after switching to galantamine. This suggests potential therapeutic benefit in switching from another acetylcholinesterase inhibitor to galantamine. The mechanism of this improvement is uncertain, but it may be attributable to the unique allosteric modulation of galantamine.
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