本文目的在探討台灣藥價差形成的機制，並利用藥價調整公式估算學名藥與原廠藥之相對藥價差比例。方法：資料上透過健保署所公佈的第五、六、七次藥價調查清單，計算個別藥品的平均價差，再估計學名藥與原廠藥的相對藥價差比例，以及利用迴歸方法探究影響相對價差比例的因素。結果：分析結果顯示學名藥藥價差略高於原廠藥藥價差，學名藥競爭降低學名藥相對原廠藥的藥價差比，療效市場競爭則會提高該藥價差比。不過，由於資料所能估計藥價差的品項較少，且多屬於相對較新進的品項，因此對藥價差比例的估計有可能傾向低估。結論：本文認為藥價政策除調整藥品絕對價格以控制醫療支出外，也應考量學名藥與原廠藥間的相對價格比例水準以保障民眾用藥選擇權益。

The aim of this paper is to discuss the mechanism underlying the pharmaceutical price gap and to estimate the relative profit margins of generic and brand-name drugs. Methods: Data were obtained from the drug list from the fifth to seventh waves of price adjustment and population claims data compiled by the National Health Insurance Database. Results: The analysis indicated that generic-to-brand price ratios and discount rates jointly determined generic-to-brand profit ratios. The profit margins of generic drugs were slightly higher than those of their brand-name counterparts. Competition between generic drugs reduced the generic-to-brand profit ratio, but therapeutic competition increased this ratio. Conclusions: The results of this study indicate that policy makers may select an appropriate generic-to-brand price ratio in order to improve resource allocation between generic and brand-name drug markets.