The Impact of Generic Competition on Brand Name Market Shares: Evidence from Micro Data

This paper analyses how market shares for brand name drugs are affected by generic competition. The analysis is based on micro data for twelve different original drugs, which are all subject to generic competition. For five of these drugs, we find that the price of the original relative to the average price of the generic substitutes significantly affects the market share of the original. In addition, the introduction of a so called "reference price" system appears to have had a significant impact on the market shares of five original drugs.