Generic entry, price competition, and market segmentation in the prescription drug market

This paper studies the effects of generic entry on post-patent price competition for 18 prescription drugs recently exposed to competition. An independent, validating test of the “generic competition paradox” is conducted using a newly created data set. Each generic entrant is associated with an average 1% increase in the branded price. The one-way error component model accounts for intermolecular competition, market segmentation, and endogeneity of entry and finds branded prices increasing by 2%. Alternative definitions of entry suggest that price competition is confined to the generic market. The unique payer-type feature of the data offers empirical evidence supporting market segmentation.