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# Revoke Approval for MSN’s Generic Hetlioz: Vanda
- URL: https://www.fdaweb.com/revoke-approval-for-msns-generic-hetlioz-vanda/
- Published: 2023-05-18T12:00:00.000Z
- Updated: 2026-09-14T18:33:07.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5154480

Vanda Pharmaceuticals is asking FDA to revoke its approval of an MSN Pharmaceuticals ANDA for generic Hetlioz (tasimelteon) capsules and order a recall of any product that has been distributed under the ANDA. The Vanda [petition](https://downloads.regulations.gov/FDA-2023-P-1985-0001/attachment%5F1.pdf?ref=fdaweb.com) says MSN failed to satisfy bioequivalence requirements in its ANDA. Hetlioz is indicated for non-24-hour sleep/wake disorder and nighttime sleep disturbances.

“MSN did not submit a study that demonstrates bioequivalence to the intended population,” the petition says. “MSN only tested its drug in 44 Indian males. To demonstrate bioequivalence, MSN did not test the drug in any women nor in a population representative of the racial and ethnic makeup of the United States. And FDA let it. FDA reviewers disregarded FDA’s own general and specific guidance and rubber-stamped MSN’s woefully inadequate study design. Indeed, an FDA reviewer specifically considered whether the demographic profile of MSN’s study satisfied FDA’s guidance, and the reviewer said ‘Yes.’”

Vanda says MSN cut serious corners in its ANDA application and the corner-cutting “raises serious safety concerns.”