All approved generic drugs were in tablet or capsule formulation and manufactured between September 30, 1984, and January 11, 2016.
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Gupta R, Kesselheim AS, Downing N, Greene J, Ross JS. Generic Drug Approvals Since the 1984 Hatch-Waxman Act. JAMA Intern Med. 2016;176(9):1391–1393. doi:10.1001/jamainternmed.2016.3411
The Hatch-Waxman Act of 1984 catalyzed the generic drug market, which now constitutes over 85% of US prescriptions.1 The number of generic alternatives to a brand-name drug affects prices; availability of at least 4 generic drugs has been associated with brand-name price reductions of approximately 60% when compared with fewer or no generics.2-4 Recently, prices for several generic drugs have increased 100-fold or more, in part because of limited competition.5 We characterized the number of generic versions for all brand-name drugs approved by the US Food and Drug Administration (FDA), along with associations between the number of generics and characteristics of brand-name drugs.
We used the Drugs@FDA database to identify novel therapeutics approved in tablet or capsule formulation between September 30, 1984, and January 11, 2016, under a new drug application (NDA). We excluded combinations with non-novel therapeutics and drugs ineligible for generic competition, including those discontinued for safety or effectiveness reasons and those with existing FDA-registered patents or exclusivity, determined in January 2016. The following brand-name drug product characteristics were determined: market status (currently marketed vs discontinued for nonsafety and/or effectiveness-related reasons); approval year; FDA priority review status; orphan status for the first approved indication; and primary therapeutic area assigned using the World Health Organization Anatomical Therapeutic Classification system.
We used the same database to identify FDA-approved abbreviated NDAs for generic versions of these drugs, as of January 11, 2016, matching on active ingredient and route of administration and selecting each generic manufacturer’s first approved dosage. We determined the proportion of drugs with any generic drugs approved and with 4 or more generic drugs approved. Among drugs with at least 1 generic approval, we determined the median number. We used χ2 and Kruskall-Wallis tests to examine associations between generic approval and brand-name drug product characteristics, using P values of .01 to account for multiple comparisons.
Among 417 novel therapeutics, 210 were eligible for generic competition. Thirty-six (17%) had no generic drugs approved and 174 (83%) had 1 or more; 133 (63%) had 4 or more (Figure). Among drugs with at least 1 generic approval, the median number was 7 (interquartile range [IQR], 4-12).
The likelihood of at least 1 and 4 or more generic drug approvals varied significantly by therapeutic category (P < .001), with neurological and psychiatric drugs having the highest rates (100% and 77%; 100% and 88%; respectively) (Table) and oncological drugs having the lowest (64% and 27%, respectively). Currently marketed drug products were significantly more likely to have at least 1 generic approval when compared with discontinued drug products (87% vs 68%; P = .002), whereas drug products that received priority review were significantly less likely to have at least 1 generic approval than those that received standard review (74% vs 88%; P = .009). Orphan-designated drugs were significantly less likely to have at least 1, as well as 4 or more, generic approvals (55% and 27%, respectively) than nonorphan-designated drugs (88% and 70%, respectively; P values < .001).
Among novel therapeutics approved in tablet or capsule formulation since the 1984 Hatch-Waxman Act and eligible for generic competition, more than 80% had at least 1 generic drug approval. However, more than one-third had 3 or fewer generic approvals, suggesting potential gaps in generic competition that can influence drug prices and increase the likelihood of price increases. For many drugs, particularly orphan-designated drugs treating smaller patient populations, insufficient potential profits and anticipated market size may not attract generic competition. Although the FDA proposed an expedited review of first potential generic versions6 as a means of addressing the current backlog of generic drug applications,7 our results suggest that prioritizing applications for drug products with 3 or fewer generic versions should also be considered.
Our study has important limitations. First, we did not examine the effect of generic approvals on drug prices. The studies that estimate the number of generic competitors associated with price reductions were published between 2005 and 2010; we are unaware of more recent data. Second, we focused on FDA-approved generic versions of brand-name drugs in tablet or capsule formulation; we did not examine intravenous, injectable or other formulations, nor account for within-class generics, which may offer reasonable, lower-priced therapeutic substitutes.
Corresponding Author: Joseph S. Ross, MD, MHS, Section of General Internal Medicine, Yale University School of Medicine, PO Box 208093, New Haven, CT 06520-8093 (firstname.lastname@example.org).
Published Online: July 18, 2016. doi:10.1001/jamainternmed.2016.3411.
Author Contributions: Mr Gupta and Dr Ross had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Gupta, Downing, Ross.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Gupta.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Gupta, Downing.
Obtained funding: Gupta.
Study supervision: Kesselheim, Ross.
Conflict of Interest Disclosures: Dr Kesselheim has received grants from the US Food and Drug Administration (FDA) Office of Generic Drugs and Division of Health Communications. Dr Ross reports receiving research support through Yale University from Medtronic, Inc. and Johnson and Johnson to develop methods of clinical trial data sharing, from the FDA to develop methods for post-market surveillance of medical devices, from the Blue Cross Blue Shield Association to better understand medical technology evidence generation, from the Centers of Medicare and Medicaid Services to develop and maintain performance measures that are used for public reporting. No other conflicts are reported.
Funding/Support: This project was not supported by any external grants or funds. Mr Gupta is supported by the Yale University School of Medicine Office of Student Research. Dr Kesselheim is supported by the Laura and John Arnold Foundation and the Harvard Program in Therapeutic Science. Dr Greene is a Greenwall Faculty Scholar.
Role of the Funder/Sponsor: The funders/sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Disclaimer: Dr Ross is section editor of JAMA Internal Medicine but was not involved in any of the decisions regarding review of the manuscript or its acceptance.
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