2026 年 52 巻 7 号 p. 495-507
In Japan, with the increasing demand for home medical care, medication management regarding drug-drug interactions (DDIs) is essential, particularly for elderly patients who are susceptible to these risks owing to declined pharmacokinetic functions, including impaired renal and hepatic metabolism. This study aimed to evaluate the prevalence and details of potential DDIs (pDDIs) and their relationship among 196 elderly patients aged over 65 years in home care and facility settings between April 2022 and March 2025 using a drug interaction checker, UpToDate®Lexidrug™. Clinically significant pDDIs were identified in 31.1％ of patients (pDDI-positive group). The pDDI-positive group had significantly higher numbers of comorbidities (P < 0.05), concomitant medications (P < 0.001), and total interactions (P < 0.001) compared to the pDDI-negative group. Among the pDDI-positive group, 95％ had concurrent renal or hepatic impairment. Multivariate logistic regression analysis identified polypharmacy (≥ 6 medications) as a significant independent factor for pDDIs (adjusted odds ratio: 2.80, P = 0.004). Regarding drug categories, hypnotics (P < 0.001) and gastric acid suppressants (P < 0.005) were significantly associated with an increased risk of pDDIs. The DDI mechanisms were based on pharmacodynamic interactions in 56.9％ of cases and on pharmacokinetic interactions in 41.2％. The primary mechanisms of pDDIs were pharmacodynamic interactions, particularly central nervous system depression (29.4％). Elderly patients undergoing home-based medical care represent a population at high risk for pDDIs, significantly influenced by polypharmacy and impaired organ functions. Integrating DDI detection systems with pharmacist intervention is essential to optimizing pharmacotherapy in this vulnerable population.
