Factors Associated With Generic Drug Uptake in the United States, 2012 to 2017

In the United States, brand-name prescription drugs remain expensive until market exclusivity ends and lower-cost generics become available. Delayed generic drug uptake may increase spending and worsen medication adherence and patient outcomes. We assessed recent trends and factors associated with generic uptake.

Among 227 drugs facing new generic competition from 2012 to 2017, we used a national claims database to measure generic uptake in the first and second year after generic entry, defined as the proportion of claims for a generic version of the drug. Using linear regression, we evaluated associations between generic uptake and key drug characteristics.

Mean generic uptake was 66.1% (standard deviation 22.1%) in the first year and 82.7% (standard deviation 21.6%) in the second year after generic entry. From 2012 to 2017 generic uptake decreased 4.3% per year in the first year (95% confidence interval, 2.8%-5.8%, P < .001) and 3.2%/year in the second year (95% confidence interval, 1.2%-5.1%). Generic uptake was lower for injected than oral drugs in the first year (38.5% vs 70.0%, P < .001) and second year (50.3% vs 86.9%, P < .001). In the second year, generic uptake was higher among drugs with an authorized generic (86.1 vs 80.1%, P = .045) and those with ≥3 generic competitors (87.7% vs 78.6%, P = .055).

Early generic uptake decreased over the past several years. This trend may adversely affect patients and increase prescription drug spending. Policies are needed to encourage generic competition, particularly among injected drugs administered in a hospital or clinic setting.