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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.

Zonder onderwerpscode: economie

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Since the 1984 passage of the Waxman-Hatch Act, generic prescription drugs have become central to disease treatment and generic drug entry and price competition has been vigorous in the U.S. Nonetheless, recent policy concern has focused on potential supply inadequacy and price increases among selected generic drugs. Details regarding the supply of generic drugs throughout the product life cycle are surprisingly unstudied. Here, we examine manufacturer entry, exit, the extent of competition and the relationship between supply structure and inflation adjusted prices among generic drugs. Our empirical approach is descriptive and reduced form, following recent innovations on the older structure-conduct-performance tradition. We employ quarterly national data on quantities, wholesale dollar sales and manufacturers from QuintilesIMS National Sales Perspective data, 2004Q4-2016Q3. Defining a market as the molecule-dosage-form, we observe that median sizes of drug markets are predominantly small, with annual inflation adjusted sales revenues of less than $10 million but increasing over time. The median number of manufacturers in each market is about two, the mean about four. We find evidence to suggest decreasing numbers of suppliers over our study period, particularly following implementation of the Affordable Care Act in 2010 and the Generic Drug User Fee Amendments of 2012, attributable both to more exit and less entry. Approximately 40 percent of markets are supplied by one manufacturer; the share of markets supplied by one or two manufacturers is observed to increase over time and is more likely among non-oral drugs and those belonging to selected therapeutic classes. We find evidence to suggest prices of generic drugs are statistically significantly increasing over time, particularly following the implementation of the 2010 Affordable Care Act and the 2012 Generic Drug User Fee Amendments. Price increases are positively correlated with reduced manufacturer counts and alternative measures of increased supplier concentration, holding all else constant. Our results suggest the market for generic drugs is largely comprised of small revenue products the supply of which has tended towards duopoly or monopoly in recent years. Therefore, it is surprising generic drug prices have not been observed to be higher and potentially risen more over our study period. This issue merits further study; we suggest several testable hypotheses based in economic theory.

Zonder onderwerpscode: economie