Specialty Drug Prices and Utilization after Loss of U.S. Patent Exclusivity, 2001-2007

Rena M. Conti, Ernst R. Berndt

This chapter is a preliminary draft unless otherwise noted. It may not have been subjected to the formal review process of the NBER. This page will be updated as the chapter is revised.

Chapter in forthcoming NBER book Measuring and Modeling Health Care Costs, Ana Aizcorbe, Colin Baker, Ernst Berndt, and David Cutler, editors
Conference held October 18-19, 2013
Forthcoming from University of Chicago Press
in NBER Book Series Studies in Income and Wealth

We examine the impact of loss of U.S. patent exclusivity (LOE) on the prices and utilization of specialty drugs between 2001 and 2007. We limit our empirical cohort to drugs commonly used to treat cancer and base our analyses on nationally representative data from IMS Health. We begin by describing the average number of manufacturers entering specialty drugs following LOE. We observe the number of firms entering the production of newly generic specialty drugs ranges between two and five per molecule in the years following LOE. However, the existence of time-varying and unobservable contract manufacturing practices complicates the definition of “manufacturers” entering the market. We use pooled data methods to examine whether the neoclassical relationship between price declines and volume increases upon LOE holds among these drugs. First, we examine the extent to which estimated prices of these drugs undergoing LOE fall with generic entry. Second, we estimate reduced form random effect models of utilization subsequent to LOE. We observe substantial price erosion after generic entry; average monthly price declines appear to be larger among physician-administered drugs (38-46.4%) compared to oral drugs (25-26%). Additionally, we find average prices for drugs produced by branded firms rise and prices for drugs produced by generic firms fall upon LOE; the latter effect is particularly large among oral drugs. In pooled models, volume appears to increase following generic entry, but this result appears to be largely driven by oral drugs. Molecule characteristics, number of manufacturers and 2007Q4 revenues are significant predictors of post-2007 drug shortages. We discuss second best welfare consequences of these results.

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This chapter first appeared as NBER working paper w20016, Specialty drug prices and utilization after loss of U.S. patent exclusivity, 2001-2007, Rena M. Conti, Ernst R. Berndt
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