[Profile of Generic Drugs Associated with the Discontinuation of the Supply]

A consistent and uninterrupted supply of pharmaceuticals is essential for optimal pharmacotherapy. However, some cases of supply disruptions and recalls have been reported. In particular, the withdrawal of some drugs from the market was occurred in recent year. Nevertheless, the characteristics of these drugs were unknown. The aim of this study was to analyze the ratio of generic drugs and the profile of generic drugs that have been withdrawn from the market. Data were collected from a drug information database for the period between April 2017 and March 2022 and analyzed for characteristics, such as price, number of suppliers, and reasons for withdrawal. The results showed a 1.4-fold increase in the number of drugs discontinued in 2021 compared with that in 2017, with 78.6% of the drugs discontinued being generic drugs. The proportion of discontinued generic drugs costing less than 10 yen (29.2%) was higher than those remaining on the market (15.0%). Additionally, the proportion of withdrawn generic drugs sold by four or more suppliers (67.6%) was higher than those that remained in the market (38.4%). In most cases (78.8%), the reasons for the discontinuation of these generic drugs were not disclosed. This study showed that most drugs withdrawn in Japan during the study period were generic drugs, characterized by low prices or many suppliers. Our study contributes to the understanding of the instability in the pharmaceutical supply chain in Japan.