FDA panel splits on imideltide listing after experts warn of unclear identity and limited safety data

The Pharmacy Compounding Advisory Committee considered whether imideltide (also called DSIP) should be placed on the federal 503A bulks list and ultimately recommended against listing both the free base and the acetate form.

FDA experts told the committee they had found inconsistent naming and certificate‑of‑analysis information in the nominations, and that critical data on impurities, aggregation, and endotoxin were missing. "If you want me to put it on the list, what form exactly do you want me to put on the list? I don't know what it is," said Russell Westyke, an FDA associate director for regulatory affairs, illustrating the agency's concern that a common or company name may mask multiple distinct chemical forms.

Public commenters were sharply divided. Dr. Marie Ezrin of Public Citizen urged the committee to reject listing, arguing the published human evidence is old, small and inconsistent and that low quality or variable products pose safety risks: "Public Citizen strongly supports the FDA's assessment that imideltide should not be included on the 503A bulks list." Industry and patient representatives argued that regulated compounding with stringent quality controls would be safer than the online research‑use market.

Committee members said their votes reflected the four statutory criteria FDA uses to evaluate bulk drug substances: physical and chemical characterization, safety, evidence of effectiveness, and historical use in compounding. After discussion, the electronic tally reported to the record showed a split outcome for both forms (6 yes / 7 no / 1 abstention reported). Several members who voted no cited uncertainty around identity and inadequate characterization; those voting yes cited patient access and some long‑standing clinical use reported by practitioners.

The FDA will consider the committee's advice as it moves forward with rulemaking. The agency emphasized that inclusion on the 503A bulks list would not make a compounded drug an FDA‑approved product and that the absence of a peer‑reviewed safety monitoring requirement under section 503A complicates post‑market oversight.