Ask the Experts - Side Effects of Donepezil
Ask the Experts - Side Effects of Donepezil
A patient on donepezil for 2 years shows a platelet count dropping to the 70,000-90,000 range, also showing some sugar in analysis. Is this noted in journals as a side effect of prolonged use of donepezil?
Eugene Flannery, PhD
A review of the literature regarding long-term effects of donepezil (Aricept) on hematologic and endocrine systems suggests no significant, lasting impact on either.
Donepezil is 1 of 4 FDA-approved acetylcholinesterase inhibitors that target the loss of cholinergic innervation to the cerebral cortex. Cholinergic innervation appears to form the basis for memory impairment in Alzheimer's disease. Increasing the level of brain acetylcholine has improved memory loss symptoms. Several clinical trials have tested the effects of galantamine, tacrine, donepezil, and rivastigmine, all of which function by blocking the breakdown of acetylcholine via inhibition of acetylcholinesterase.
In trials enrolling more than 1700 patients worldwide, donepezil has been given to patients in various stages of Alzheimer's disease. For the most part, patients in these trials were treated for up to 1 year with donepezil. Among the approximately 900 patients treated in the United States, less than 120 received donepezil for more than 1 year.
Diabetes, thrombocytopenia, and anemia were reported in less than 5% of cases studied, although the significance of these findings is further diluted by the fact that similar frequencies were found among the placebo control groups. Furthermore, none of these differences reached statistical significance.
Patients on donepezil for long periods of time are probably in the advanced stages of Alzheimer's disease, and have likely developed comorbid conditions requiring additional medications. Such medications and/or conditions probably contribute more to the presence of elevated blood sugar levels and low platelet counts than does the use of donepezil.
Platelet counts in the 70,000-90,000 range are seldom, if ever, life-threatening. Even if a link between donepezil and thrombocytopenia were established, as long as the degree of thrombocytopenia is mild, continued use of a clinically beneficial medication is likely indicated. The same holds true for blood sugar elevations, as long as no clinically significant complications ensue.
A patient on donepezil for 2 years shows a platelet count dropping to the 70,000-90,000 range, also showing some sugar in analysis. Is this noted in journals as a side effect of prolonged use of donepezil?
Eugene Flannery, PhD
A review of the literature regarding long-term effects of donepezil (Aricept) on hematologic and endocrine systems suggests no significant, lasting impact on either.
Donepezil is 1 of 4 FDA-approved acetylcholinesterase inhibitors that target the loss of cholinergic innervation to the cerebral cortex. Cholinergic innervation appears to form the basis for memory impairment in Alzheimer's disease. Increasing the level of brain acetylcholine has improved memory loss symptoms. Several clinical trials have tested the effects of galantamine, tacrine, donepezil, and rivastigmine, all of which function by blocking the breakdown of acetylcholine via inhibition of acetylcholinesterase.
In trials enrolling more than 1700 patients worldwide, donepezil has been given to patients in various stages of Alzheimer's disease. For the most part, patients in these trials were treated for up to 1 year with donepezil. Among the approximately 900 patients treated in the United States, less than 120 received donepezil for more than 1 year.
Diabetes, thrombocytopenia, and anemia were reported in less than 5% of cases studied, although the significance of these findings is further diluted by the fact that similar frequencies were found among the placebo control groups. Furthermore, none of these differences reached statistical significance.
Patients on donepezil for long periods of time are probably in the advanced stages of Alzheimer's disease, and have likely developed comorbid conditions requiring additional medications. Such medications and/or conditions probably contribute more to the presence of elevated blood sugar levels and low platelet counts than does the use of donepezil.
Platelet counts in the 70,000-90,000 range are seldom, if ever, life-threatening. Even if a link between donepezil and thrombocytopenia were established, as long as the degree of thrombocytopenia is mild, continued use of a clinically beneficial medication is likely indicated. The same holds true for blood sugar elevations, as long as no clinically significant complications ensue.
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