Objectives: The objectives of this study are to evaluate the current situation of concomitant drug use by community-dwelling elderly dementia patients, and to extract factors influencing the presence of potentially inappropriate medications (PIMs).
Method: The research subjects were patients 65 years of age or older for whom concomitant drugs were prescribed on the same prescription form as donepezil hydrochloride.  One hundred and twenty community pharmacies randomly selected from 28 of the 47 prefectures throughout Japan.  Main research topics were sex, age, the clinical department to which the prescribing physician belonged, daily dosage of donepezil, and concomitant drugs.  Concomitant drugs were evaluated using the Beers Criteria: the Japanese Version. Furthermore, to search factors influencing the presence of PIMs, logistic regression analysis was used.
Results: Data for 335 patients were extracted.  The average number of concomitant drug cases per patient were 4.2 (SD 2.6), and 109 patients (32.5%) were prescribed PIMs.  A logistic regression analysis confirmed that significant factors influencing the presence of PIMs were “the clinical department to which the prescribing physician belonged” (OR 4.80, 95%CI 1.01-22.72), “concomitant drug cases” (OR 1.26, 95%CI 1.13-1.41) and “the presence of concomitant use of central nervous system agents” (OR 5.82, 95%CI 3.35-10.11).
Conclusion: This study revealed that more than a few cases of community-dwelling elderly patients of dementia were using concomitant drugs with potential risks.  It suggested that influencing factors were “the specialty of the prescribing physician” and “the presence of concomitant use of central nervous system agents.”