Glossary
FDA Category 2
Also called Category 2, Cat 2, 503A Category 2, Significant safety risks list
An FDA list of bulk ingredients that were nominated for compounding but that FDA says may present significant safety risks. Pharmacies are not expected to compound with them under the interim policy.
In more detail
When someone nominates an ingredient for the 503A or 503B bulk lists, FDA sorts it under interim policies while it reviews. Category 2 is for substances where FDA has identified potential significant safety risks. Several popular research peptides have been placed there, and FDA's page lists each one with the date and the concern.
The list moves. Nominations get withdrawn, items come off, and advisory committees revisit some. A peptide leaving Category 2 does not make it approved or automatically allowed for compounding.
Why it matters
Category 2 status is the main reason many peptides cannot be legally compounded by US pharmacies. Each compound page on this site shows its current regulatory status with dates.
Related terms
- 503A vs 503BThe two federal paths for drug compounding in the US. 503A covers state-licensed pharmacies filling patient prescriptions; 503B covers FDA-registered outsourcing facilities that follow manufacturing standards.
- Compounded vs brandedA branded drug is the FDA-approved product from its maker. A compounded drug is mixed by a pharmacy or outsourcing facility and is not FDA approved.
- Research use only (RUO)A label sellers put on compounds that are not approved drugs, stating they are sold for laboratory research and not for human use.
Peptides where this comes up
Sources
Each source is labeled by where the information comes from. How we label sources
- RegulatoryCertain bulk drug substances for use in compounding that may present significant safety risks(opens in a new tab)
FDA · checked
- RegulatoryBulk drug substances nominated for use in compounding under section 503A (category lists)(opens in a new tab)
FDA · checked
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