Review on 505(b)(2) Drug Products Approved by USFDA from 2010 to 2020 Emphasizing Intellectual Property and Regulatory Considerations for Reformulations and New Combinations

Repurposing is considered an attractive approach for developing new drug products. However, it consists of challenges relating to intellectual property (IP) protection, and regulatory approvals. This study aimed to analyze the recent trends in repurposed drugs approved by USFDA from 2010 to 2020 and to assess the challenges connected with bridging study requirements, patent protection, and exclusivities. Out of 1001 NDAs, 570 were approved via 505(b)(2) pathway. Of 570 NDAs, the highest number of approvals are allied to type 5-new formulations (42.4%), followed by type 3-new dosage forms (26.4%) and type 4-new combinations (13.1%). Of 570 NDAs, 470 are considered to examine the patent and exclusivity protection of which 341 have patent and/or exclusivity. A total of 97 type-3 and type-5 and 14 type-4 drugs have been approved based on human bioavailability/bioequivalence (BA/BE) data. For 131 type-3 and type-5 and 34 type-4 drugs, the applicants conducted new clinical (efficacy and/or safety) studies along with BA/BE (100 drugs) or without BA/BE (65 drugs) studies. In this review, mechanistic reasons for conducting new clinical investigations, IP and regulatory considerations along with broader perspective on new pharmaceutical approaches employed in 505(b)(2) drugs are illustrated that provide guidance for development of reformulations and combinations.