Tolerability, Adherence to Alzheimer's Drugs Assessed
Findings from the first real-world study comparing patient adherence and tolerability to cholinesterase inhibitors have shown that by 18 weeks of treatment, only 1/2 of patients prescribed these drugs were continuing treatment with them. The study has been published in the Journal of the American Geriatrics Society.
Currently, the 3 medications approved by the Food and Drug Administration (FDA)—donepezil, galantamine, rivastagmine—require an up titration from the initial dose to the target dose for maximum benefit. This effect can be achieved in 4-8 weeks according to drug manufacturers but study data indicated that by 18 weeks, only 1/2 of the patients on any of the 3 medications were still taking them.
The cholinesterase inhibitors do not cure Alzheimer's disease but "by not getting patients to target doses, we aren't optimizing the potential benefits these medications may provide," said Noll Campbell, PharmD, lead author of the study, from IU Center for Aging Research and Regenstrief Institute.
The study patients (n=196) were taking about 8 other medications, representing a "real-world" population. A little more than half of the patients experienced an adverse effect which affected their decision to discontinue treatment. The frequency of musculoskeletal adverse effects (eg, pain, muscle cramps) and neurologic effects (eg, dizziness, nightmares, headaches) were as common as gastrointestinal side effects (eg, vomiting, nausea, diarrhea). These effects were reported to have happened at starting dose or early during treatment.
Overall, the researchers found no variation in tolerability or adherence to the 3 medications based on gender, race, education or age. During the 18-week duration, the target dose was obtained by 53% of patients taking donepezil, 19% of patients taking rivastigmine, and 5% of patients taking galantamine.
Apart from the high frequency of adverse effects, cost was cited as the only reason for discontinuation that differed between the medications. Study patients were more likely to begin and continue treatment with donepezil, a consistently preferred medication with the lowest patient cost.
Of the patients prescribed galantamine, 14% stopped for cost reasons as well as 17% of those prescribed rivastigmine. Some switched to donepezil and continued to be followed for tolerability assessments.
Dr. Campbell stated, "Physicians should be aware of the impact of side effects, many of which are shared with other medications that the patient is taking, on both the adherence to the medication and quality of life."
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