(103) Switching Patterns of Mixed Amphetamine Salt Products in the FDA's Sentinel Distributed Database

Publication Number: 777

Background: In the United States, the generic equivalents of Adderall are widely used in the form of mixed amphetamine salt (MAS) products for the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. Some of the immediate release (IR) forms of these generics have been subject of passive surveillance reports submitted to the U.S. Food and Drug Administration (FDA) signaling lack of effectiveness.

Objectives: To examine utilization and switching patterns among commercially-insured individuals treated with MAS IR in the FDA’s Sentinel Distributed Database.

Methods: We identified ADHD and narcolepsy patients ages 15-64 years with at least 60-day continuous supply of selected generic MAS IR products grouped by Abbreviated New Drug Application (ANDA): 202424, 040440, 040422, 040439, and 040480, among five Sentinel Data Partners from January 1, 2013 through December 31, 2019. We evaluated switching patterns to a higher dose of any MAS IR, away from an ANDA product of interest, and to an ANDA product of interest.

Results: We identified the largest utilization for ANDA 040422 (3,666,201 dispensings) and the lowest for ANDA 040480 (55,764 dispensings) with a median of 30-day supply per dispensing. Similarly, we observed the greatest number of episodes with at least 60-day continuous supply for ANDA 040422 (n=525,771), followed by ANDA 202424 (n=181,693), ANDA 040439 (n=62,363), ANDA 040440 (n=21,143), and ANDA 040480 (n=8,792). Few episodes resulted in a switch to a higher dose product (range 1.9-3.2%). Of these, median days until the switch ranged between 21 (ANDA 040480) and 35 days (ANDA 040422). The proportion of episodes resulting in a switch to another product varied by ANDA group: 42.0% of ANDA 040480 episodes resulted in a switch to another product, contrasted with only 9.3% of ANDA 040422 episodes. Mean time to switch away was 30 and 40 days, respectively. Of those with a first switch away, ANDA 040422 episodes (48.6%) and ANDA 202424 (43.0%) were most likely to end with a switch back to the same product; ANDA 040480 episodes were least likely (24.1%). Of those episodes that started on another and switched to an ANDA product of interest, about one-third (range 27.1% to 37.0%) switched back to the same product. These switches back had a median time to switch of about 30 days.

Conclusions: This observational study, which cannot consider factors such as market availability, cost, patient and/or provider preferences, does not suggest decreased effectiveness for any selected ANDA product based on the same switching patterns observed for the other ANDAs.