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Alzheimer's: too many patients exposed to drug interactions

A study has shown that many Alzheimer’s patients being treated with an acetylcholinesterase inhibitor are exposed to dangerous interactions with other drugs.

France’s Health Data Institute (Institut des données de santé, IDS) authorised Prescrire to access reimbursement data from the French national health insurance system (using a representative sample that preserved patients’ anonymity and that of the prescribing physicians) for a study on the three acetylcholinesterase inhibitors widely used for treating Alzheimer’s disease: donepezil, rivastigmine, and galantamine.

Between 2003 and 2011, 4148 patients over the age of 60 taken from this sample had been exposed to at least one of these three drugs. For 1820 of these patients (i.e. 44%), an acetylcholinesterase inhibitor and at least one other drug known to expose patients to bradycardia – a slowing down of the heart rate, which can cause faintness, syncope and falls, particularly in elderly patients – were dispensed at least once within the same month. An acetylcholinesterase inhibitor and a neuroleptic were dispensed at least once within the same month to 1384 (i.e. 33% of the 4148 patients). These figures are worrying because neuroleptics increase mortality in patients suffering from dementia. And for 333, or 8% of the 4148 patients, an acetylcholinesterase inhibitor and an antimuscarinic drug for urinary disorders were dispensed at least once within the same month. These combinations are illogical and counterproductive, since the anticholinergic effects of antimuscarinic drugs work against the cholinergic effects of acetylcholinesterase inhibitors.

The age at death appeared to be lower in the patients who took these acetylcholinesterase inhibitors for the longest time. These data are worrying since clinical trials conducted over six months showed a higher mortality rate with these drugs.

©Prescrire 1 June 2014

"Alzheimer’s disease in France: too many patients exposed to drug interactions involving cholinesterase inhibitors" Prescrire Int 2014; 23 (150): 156. (Pdf, subscribers only).
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