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Are Alzheimer’s Patients Given Drugs That Cancel Each Other?


One of the distressing facts about Alzheimer’s disease is that currently available drugs cannot cure or halt progression of the disease. Now a new study reveals that some Alzheimer’s patients are given drugs that cancel each other out, which means patients are not getting any benefits from either drug.

Some Alzheimer’s patients may be missing drug benefits

The main medications used to treat Alzheimer’s disease are in a class called cholinesterase inhibitors, which include the FDA (Food and Drug Administration) approved medications donepezil (Aricept), which is approved to treat all stages of Alzheimer’s; and rivastigmine (Exelon) and galantamine (Razadyne), both approved to treat mild to moderate Alzheimer’s. These drugs prevent the breakdown of acetylcholine, a chemical messenger that is essential for memory and learning.

Another class of drugs often prescribed for people with Alzheimer’s—but which are for other conditions such as gastrointestinal disorders, urinary incontinence, depression, and Parkinson’s disease—are anticholinergics. These drugs (e.g., diphenhydramine [Benadryl], oxybutynin [Ditopan]) block the action of acetylcholine and can have a negative effect on mental function in the elderly as well as antagonize each other, which means drugs in neither class will help the patient.

The new study, which was conducted by scientists from Group Health Research Institute (GHRI), looked at how often Alzheimer’s patients may be receiving medications that have opposite effects. According to Denise Boudreau, PhD, RPh, an associate scientific investigator at GHRI, “There’s concern that if someone is taking both types of drugs—cholinesterase inhibitors and anticholinergic medications—they will antagonize each other, and neither will work.”

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A total of 5,625 individuals ages 50 or older participated in the study. All had received a new prescription for cholinesterase inhibitors between 2000 and 2007. An evaluation of the medication use of the study participants revealed that 37% were also taking at least one anticholinergic drug, more than 11% were taking two or more, and 25% used both types of drugs for more than 1 year.

The reassuring part of this study was that “we did not observe an association between simultaneous use of the two types of drugs and increased risk of death or nursing home placement,” according to Dr. Boudreau. She noted, however, that simultaneous use of these medications is “not optimal clinical practice,” and that preventing such use "could also be a chance to reduce waste in health care spending.”

Individuals who have Alzheimer’s disease are frequently prescribed drugs from both of these classes because this patient population often has several medical conditions. Another reason for prescribing anticholinergics is that they can help reduce the adverse effects of the cholinesterase inhibitors.

Therefore the simultaneous use of drugs from two different classes in Alzheimer’s patients is a dilemma that families and health care providers must examine so the benefits possible from each drug do not cancel each other out. Dr. Boudreau noted that “A good first step is to have clearly agreed-upon goals for therapy and a plan to monitor for effects and side effects.”

Group Health Research Institute