Testing & quality

Salt form

Also known as: tfa salt · acetate salt · trifluoroacetate · counter-ion

The counter-ion paired with a peptide — commonly trifluoroacetate (TFA) or acetate — which contributes mass but no activity.

In plain terms

Synthesis and purification leave a counter-ion behind. TFA is the usual residue of reverse-phase purification; acetate is generally preferred for material intended for human use. The salt contributes to the vial’s weight and therefore reduces net peptide content.

Salt form has a second, regulatory meaning. FDA has specifically flagged compounded products using unapproved salt forms such as semaglutide sodium and semaglutide acetate, which are different active ingredients from the approved drug — and to which the approved drug’s safety and efficacy data do not transfer.

Guides that use this term

Compounded semaglutide and tirzepatide: what changed

The shortages ended, and with them the enforcement discretion that allowed mass compounding of semaglutide and tirzepatide. What FDA actually said, with the dates, and what remains permitted.

Sources

FDA — Concerns with unapproved GLP-1 drugs used for weight loss

Educational reference only. Pepperz does not provide medical advice, diagnosis, treatment, prescribing guidance, or dosing recommendations.