LTP·01learntopeptide
Healing & repairEvidence B3 cited

Thymulin

aka Thymulin · FTS · facteur thymique serique · serum thymic factor

A zinc-dependent nonapeptide hormone produced by thymic epithelial cells that is essential for T-cell maturation and immune reconstitution. Thymulin levels decline dramatically with thymic involution during aging.

Molecular wt
858.9g/mol
Formula
C33H54N12O15
CAS
63958-90-7
Half-life
30 min
estimated
Tmax
1 h
Route
Subcutaneous injection
PubChem
3085284

Sequence

One-letter8 residues

<Glu>AKSQGGSN

Three-letter

pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn

Read this before quoting the sequence
Nonapeptide (INN: nonathymulin), formerly called facteur thymique serique (FTS) / serum thymic factor. Residue 1 is pyroglutamate, so it has no standard single-letter representation; the one-letter form is written with <Glu> for pGlu. Biological activity requires a bound zinc ion - the zinc-free nonapeptide is inactive - and the formula/MW below are for the zinc-free peptide.
Source ↗

Mechanism of action

Thymulin requires zinc for its biologically active conformation. It binds to high-affinity receptors on T-cell precursors, promoting their differentiation and maturation. Thymulin modulates the balance between T-helper and T-regulatory cells, enhances natural killer cell activity, and supports thymic function. Its decline with age contributes to immunosenescence.

What the evidence actually shows

Grade B

Clinical studies in immunocompromised patients show improved T-cell counts and immune function. Thymulin restoration in aged animals reverses aspects of immunosenescence. Zinc dependency well-established.

Regulatory status

Status
Not approved as a medicine anywhere that could be verified. No Drugs@FDA record. The single DailyMed listing under this name is an unapproved homeopathic pellet product and does not constitute drug approval.
Clinical stage
No registered clinical trials - a ClinicalTrials.gov intervention query for thymulin returns zero studies. Evidence base is preclinical and physiological.
WADA
Not named on the WADA 2026 Prohibited List.
Source ↗

Pharmacokinetics

Half-life
30 min
Tmax
1 h
Absorption
subcutaneous
Elimination
renal
Washout
1 days
Low-confidence pharmacokinetics
These figures are recorded as estimated rather than measured in a published PK study. Treat them as an order of magnitude. Anything downstream of them — accumulation, steady state, washout — inherits that uncertainty.

Dosing — what backs each figure

Thymulin (serum thymic factor / FTS) was given to humans in the 1980s as the synthetic nonapeptide 'nonathymulin' at 1-10 mg/day, with 5 mg/day the most effective dose in rheumatoid arthritis and a subcutaneous 6-month course tested (unsuccessfully) in multiple sclerosis. It is not approved anywhere and no modern dosing exists.

ClinicalApproved labelling or a published human trial

  • Nonathymulin (synthetic thymulin nonapeptide) 1, 5 or 10 mg/day; 5 mg/day was the most effective dose

    Adults with rheumatoid arthritis; two randomised double-blind placebo-controlled trials · not stated in the retrievable abstract

    Amor B et al., Ann Rheum Dis 1987;46(7):549-54 ↗

  • Subcutaneous nonathymulin (synthetic serum thymic factor) for 6 months, followed for a further 6 months; dose not stated in abstract

    40 patients with evolutive multiple sclerosis and moderate disability; randomised double-blind placebo-controlled pilot · subcutaneous

    Roullet E et al., Acta Neurol Scand 1989;80(6):575-8 ↗

Handling and storage

No compound-specific stability data exists
No approved medicinal product exists (the only DailyMed entry for the name is an unapproved homeopathic pellet, 'THYMULINE (NONATHYMULIN) PELLET', which is not a source for peptide handling). No compound-specific stability data located in indexed literature. Ported storage text ('-20C ~24 months lyophilised; 2-8C ~4 weeks reconstituted') is generic peptide-handling boilerplate that was applied identically across many compounds in this dataset. It is not sourced to this compound. General peptide handling still applies — reconstitute gently, keep it cold, keep it dark — but any specific figure you see quoted for this compound elsewhere is someone's assumption, not a measurement.
→ Reconstitution walkthrough→ Reconstitution calculator

Safety

References (3)

Data provenance

Chemistry and citations on this page were checked against primary sources on 2026-08-14. Values that could not be verified were left blank rather than filled with a plausible guess.

Could not verify
storage.lyophilized, storage.reconstituted, storage.lightSensitive, reconstitution.solvent

Research use only
This profile is educational reference material. It is not medical advice, not a prescription, and not an endorsement of self-administration. Compounds discussed here are research chemicals and most are not approved for human therapeutic use.

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