The effect of generic market entry on antibiotic prescriptions in the United States

Abstract

When patented, brand-name antibiotics lose market exclusivity, generics typically enter the market at lower prices, which may increase consumption of the drug. To examine the effect of generic market entry on antibiotic consumption in the United States, we conducted an interrupted time series analysis of the change in the number of prescriptions per month for antibiotics for which at least one generic entered the US market between 2000 and 2012. Data were acquired from the IQVIA Xponent database. Thirteen antibiotics were analyzed. Here, we show that one year after generic entry, the number of prescriptions increased for five antibiotics (5 to 406%)—aztreonam, cefpodoxime, ciprofloxacin, levofloxacin, ofloxacin—and decreased for one drug: cefdinir. These changes were sustained two years after. Cefprozil, cefuroxime axetil and clarithromycin had significant increases in trend, but no significant level changes. No consistent pattern for antibiotic use following generic entry in the United States was observed.

Impact of Generic Entry on Hospital Antimicrobial Use: A Retrospective Quasi-Experimental Interrupted Time Series Analysis

“…In our study, two reasons may explain the increase in the use of meropenem: an increment in the incidence of multidrug-resistant organisms (data not shown) and a looser antibiotic policy at the hospital, specifically regarding empirical therapy. This last reason may be related to a reduced control by antimicrobial stewardship teams, who were unfortunately required to focus on more expensive molecules [10]. Antimicrobial stewardship teams need to face limited resources, which necessitates prioritizing those interventions that might have a greater impact [15].…”

“…Regarding meropenem, its use declined in most of the countries except Spain, where a significant positive change in slope was found. Kallberg et al recently assessed the effect of generic market entry on antibiotic consumption in the USA [10]. The use of aztreonam, cefpodoxime, ciprofloxacin, levofloxacin, and ofloxacin increased, whereas that of cefdinir decreased.…”

“…On the contrary, for others, an increase in the cost may decrease adherence, especially in settings with low economic resources [2]. Kallberg et al described the influence of co-interventions [10]. The introduction of other (i.e., inhaled) formulations, the presence of outbreaks (i.e., anthrax), or safety reports may alter antimicrobial use [10].…”

“…Other works have assessed the impact caused by the introduction of generic antimicrobials [10][11][12]. In the last study, showing the impact of generic entry in the United States of America (USA), the number of prescriptions increased for aztreonam, cefpodoxime, ciprofloxacin, levofloxacin, and ofloxacin, while it decreased for cefdinir [10].…”

“…Other works have assessed the impact caused by the introduction of generic antimicrobials [10][11][12]. In the last study, showing the impact of generic entry in the United States of America (USA), the number of prescriptions increased for aztreonam, cefpodoxime, ciprofloxacin, levofloxacin, and ofloxacin, while it decreased for cefdinir [10]. In Germany, the reduction in the price of fluoroquinolone was related to a 36% decline in its acquisition cost but, on the other hand, to a rise in its use of 46% [11].…”