TB-500 Compounding Pharmacy: How to Read a Certificate of Analysis

Why TB-500 certificates are harder to read than most

FDA's July 2026 review found no USP or National Formulary monograph for TB-500 and no FDA-approved drug containing it [1].

Identity is the line worth reading hardest. FDA found several salts and derivatives, including different active moieties, sold under the name TB-500 [1]. A useful document identifies the N-acetylated Ac-LKKTETQ fragment at approximately 889 g/mol and states the form, free base or acetate [1].

Esposito and colleagues identified that N-acetylated 17 to 23 fragment in TB-500 by HPLC with high-resolution mass spectrometry. It was an analytical chemistry study of a product suspected of doping use, not a clinical study [4].

What no certificate can answer

Compounded drugs are not FDA-approved, and FDA does not review them for safety, effectiveness or quality before they reach patients [3]. FDA found TB-500 not well characterized, with inconsistent naming and no impurity, aggregate or endotoxin data, and no immunogenicity or aggregation studies. Immunogenicity from aggregation and peptide-related impurities is FDA's stated concern for the injectable [1]. An adverse-event database search through March 26, 2025 retrieved no TB-500 reports, and FDA found no published case reports [1].

TB-500 appears in none of the categories on FDA's bulk substance lists for state-licensed pharmacies and physicians or for outsourcing facilities [5][6][2]. FDA staff recommended against adding it to the bulks list [1]. The July 23, 2026 advisory committee voted in favor of adding it, which was advice only, and TB-500 is not on the list [7][8]. HHS's October 2026 draft enforcement-discretion policy names TB-500 acetate for subcutaneous or intramuscular injection. It says HHS does not intend to take enforcement action where its conditions are met, one of them an FDA-registered manufacturer with a certificate of analysis. The notice states it is not binding, and it is not an approval [8][9].

Three things to check on the document

• The fragment and the form: N-acetylated Ac-LKKTETQ, about 889 g/mol, with free base or acetate named [1].
• The bulk substance maker: an FDA-registered establishment, a condition for using a bulk substance in compounding [2].
• Impurity and endotoxin results, the categories FDA found missing for TB-500 [1].