THERAPEUTIC SUBSTITUTION POST‐PATENT EXPIRY: THE CASES OF ACE INHIBITORS AND PROTON PUMP INHIBITORS
研究欧洲六国1991-2006年数据发现，专利到期后，医生和患者会转向同类中仍在专利保护期的药物，导致仿制药政策失效并增加药费支出。
This paper examines whether there is a switch in total (originator and generic) consumption after generic entry from molecules that face generic competition towards other molecules of the same class, which are still in-patent. Data from six European countries for the time period 1991 to 2006 are used to study the cases of angiotensin-converting enzyme inhibitors and proton pump inhibitors. Empirical evidence shows that patent expiry of captopril and enalapril led to a switch in total (off-patent originator and generic) consumption towards other in-patent angiotensin-converting enzyme inhibitors, whereas patent expiry of omeprazole led to a switch in consumption towards other proton pump inhibitors. This phenomenon makes generic policies ineffective and results in an increase in pharmaceutical expenditure due to the absence of generic alternatives in the market of in-patent molecules.