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TB-500 and Imaging Contrast Dye: What You Need to Know Before Your Scan

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At a glance

  • Drug class / synthetic 7-amino-acid fragment of thymosin beta-4 [1]
  • FDA status / not approved; no FDA-approved product contains it [1]
  • Studies of TB-500 with contrast dye / none identified; FDA found no human study of TB-500 for any purpose [1]
  • Human pharmacokinetic data / none by any route [1]
  • Main FDA safety concern / immunogenicity from injected peptides [1]
  • Anti-doping status / prohibited at all times by WADA, class S2.3 [2]

Does TB-500 interact with contrast dye?

FDA searched PubMed, Embase, ClinicalTrials.gov and other sources and found no article in which TB-500 was given to a human, and no published case reports [1]. With no human pharmacokinetic or pharmacodynamic data, there is nothing from which to judge how TB-500 might behave alongside iodinated or gadolinium contrast [1].

An unmeasured interaction is not a safe one.

What is known about TB-500 in the body

Animal studies indicate that subcutaneous or intraperitoneal TB-500 reaches the bloodstream and is broken down by hydrolysis into smaller peptides; FDA found no animal studies using intramuscular injection [1]. There is no approved dose and no human dosing study of TB-500, and doses used in trials of recombinant full-length thymosin beta-4, a different product, do not apply to it [1].

Does TB-500 affect kidney function?

Kidney effects have not been measured. FDA found no nonclinical toxicity studies of TB-500, no human pharmacokinetic or pharmacodynamic data, and no published article in which TB-500 was given to a human [1]. The one case FDA's BPC-157 review describes involving a blended BPC-157 plus TB-500 product was a woman who developed widespread skin hyperpigmentation and gum darkening; because the product held two peptides, FDA said it cannot tell whether either caused it [3].

Is there a label to check?

TB-500 is not an FDA-approved drug and has no USP or National Formulary monograph [1]. FDA's Pharmacy Compounding Advisory Committee voted in favor of adding TB-500 to the bulks list on July 23, 2026, against FDA staff's recommendation, but that vote is advice only and TB-500 is not on the list [4][1]. HHS's October 2026 draft policy naming TB-500 acetate for injection is not an approval and is not binding [5][6].

Frequently asked questions

Does TB-500 interact with contrast dye?
No interaction has been established. FDA found no human study of TB-500 for any purpose and no human pharmacokinetic data by any route, so the interaction is unmeasured rather than ruled out [1].
Is there a studied waiting period between TB-500 and a CT or MRI?
No. There is no human dosing study of TB-500 and no approved dose, so no timing rule around a contrast scan has been established [1].
Does TB-500 affect kidney function?
Kidney effects have not been measured. FDA found no nonclinical toxicity studies of TB-500 and no human data [1].
Is TB-500 FDA approved?
No. FDA found no approved drug containing it and no USP or National Formulary monograph [1]. The July 2026 advisory committee vote was non-binding advice, and HHS's October 2026 peptide policy is a draft, not an approval [4][5].

References

  1. U.S. Food and Drug Administration. U.S. Food and Drug Administration
  2. World Anti-Doping Agency. World Anti-Doping Agency
  3. U.S. Food and Drug Administration. U.S. Food and Drug Administration
  4. U.S. Food and Drug Administration. U.S. Food and Drug Administration
  5. Official web page. Official web page
  6. Official web page. Official web page
Evidence overview for TB-500 and Imaging Contrast Dye: What You Need to Know Before Your Scan