Generic take-up in the pharmaceutical market following patent expiry: A multi-country study

Abstract

This article analyzes for the pharmaceutical market in the United States, the United Kingdom, Germany, and Japan: (a) the determinants of generic entry; (b) the determinants of the entry lag when there is generic entry; and (c) the impact on original brand sales of generic entry. The results suggest that the larger the market, the greater is the probability of both generic entry and the subsequent impact on original brand sales. These results imply that the value of a patent does not end with patent expiry, as the literature commonly assumes, and estimates of patent postexpiry values are obtained. © 2000 Elsevier Science Inc.