Comparison of Outcomes Following a Switch From a Brand to an Authorized Versus Independent Generic Drug

Abstract

Authorized generics are identical in formulation to brand drugs, manufactured by the brand company but marketed as a generic. Generics, marketed by generic manufacturers, are required to demonstrate pharmaceutical and bioequivalence to the brand drug, but repetition of clinical trials is not required. This retrospective cohort study compared outcomes for generics and authorized generics, which serves as a generic vs. brand proxy that minimizes bias against generics. For the seven drugs studied between 1999 and 2014, 5,234 unique patients were on brand drugs prior to generic entry and 4,900 (93.6%) switched to a generic. During the 12 months following the brand-to-generic switch, patients using generics vs. authorized generics were similar in terms of outpatient visits, urgent care visits, hospitalizations, and medication discontinuation. The likelihood of emergency department (ED) visits was slightly higher for authorized generics compared with generics. These data suggest that generics were clinically no worse than their proxy brand comparators.

Figure 1

Time from generic entry (index date) to generic switch by drug type

Figure 2. Adjusted comparison of health services utilization and medication discontinuation for authorized generic vs. generic

AG = authorized generic; “Generic” refers to all other independing generics filed under an Abbreviated New Drug Application (ANDA) Estimates greater than 1 suggest that the outcome was more likely to occur in the AG group, while estimates less than 1 suggest that the outcome was more likely to occur in the generic group.