Polypharmacy, Inappropriate Prescribing and Adverse Drug Events in Japan

Adverse drug events (ADEs) are harmful causes for illness and injury in patents and these events are related to polypharmacy and inappropriate prescribing. As Japanese population become older, prescribed drugs are rapidly growing because of the frequent multimorbidity among old patients and the increased availability of new drugs. Thus, many Japanese elderly now take a large number of medications well over the common definition of polypharmacy (5 drugs or greater in a patient). Additionally, inappropriate prescribing is prevalent probably from providers’ factor (fee for service system for a clinic or hospital pharmacy and strong promotion despite relatively little absolute risk reduction by drug use from pharmaceutical companies) as well as patients’ factor (requests from patients for medications such as a benzodiazepine for insomnia).