Impact of therapeutic substitution on sales of medicines in Japan

Research Project

Project/Area Number	15K08126
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Medical pharmacy
Research Institution	National Hospital Organization Headquarters
Principal Investigator	Imai Shinobu 独立行政法人国立病院機構本部(総合研究センター), 診療情報分析部, 主任研究員 (50608750)
Co-Investigator(Kenkyū-buntansha)	伏見清秀東京医科歯科大学, 大学院医歯学総合研究科, 教授 (50270913) 堀口裕正独立行政法人国立病院機構本部(総合研究センター), 診療情報分析部, 副部長 (50401104)
Co-Investigator(Renkei-kenkyūsha)	Sundell Karolina Andersson University of Gothenburg
Project Period (FY)	2015-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000) Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2015: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Keywords	後発医薬品 / スイッチ現象 / 先発医薬品 / 降圧剤 / 新薬へのスイッチ / スウェーデン
Outline of Final Research Achievements	The generic substitution of medicines has been introduced in Europe since the 1990s to increase price competition and the use of cheaper equivalents. Patent expiry is assumed to be associated with changes in sales patterns, particularly when combined with generic substitution. This project examined to what extent patent expiry on efficacy influence the pharmaceutical sales patterns in Japan. Angiotensin-converting enzyme inhibitors and angiotensin Ⅱ antagonists (ARBs) were selected, since they are widely used in both Japan. Interventions were patent expiry on lower efficacy for two ARBs. Seasonal autoregressive integrated moving average modelling with intervention was used to analyse changes in sales volumes. Conclusions: We found sales patterns of antihypertensive medicines were to a large extent affected by information on efficacy rather than patent expiry. However, further assessment is needed for other medicine groups and settings.