Multi-dose drug dispensing and inappropriate drug use: A nationwide register-based study of over 700 000 elderly

OBJECTIVE: To investigate whether the use of multi-dose drug dispensing is associated with potentially inappropriate drug use (IDU). DESIGN: Cross-sectional nationwide register-based study. SETTING: Sweden. SUBJECTS: People aged >or=75 years registered in the Swedish Prescribed Drug Register during October-December 2005. MAIN OUTCOME MEASURES: Potentially IDU, i.e. anticholinergic drugs, long-acting benzodiazepines, concurrent use of three or more psychotropic drugs, and combinations of drugs that may lead to potentially serious drug-drug interactions (DDIs). RESULTS: After adjustment for age and number of dispensed drugs, any IDU, anticholinergic drugs, and three or more psychotropic drugs were associated with multi-dose drug dispensing, whereas the opposite relationship prevailed for long-acting benzodiazepines among women and potentially serious DDIs in both men and women. Among the subjects aged 75-79 years, multi-dose drug dispensing was even more strongly associated with any IDU, anticholinergic drugs, three or more psychotropic drugs in both men and women, and long-acting benzodiazepines among men. CONCLUSION: Our results indicate that multi-dose users may be more exposed to potential IDU. However, multi-dose users seem to have a lower probability of potentially serious DDIs. Future research on multi-dose drug dispensing is necessary to ensure a high quality of drug therapy within this system.