Thymopentin
TP-5 Synthetic Thymic Pentapeptide
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
Thymopentin is a synthetic pentapeptide (Arg-Lys-Asp-Val-Tyr) reproducing residues 32-36, the active fragment, of the thymic hormone thymopoietin. Human evidence is real but old and modest: a two-center double-blind placebo-controlled trial in 100 atopic dermatitis patients (Stiller et al., 1994) found a significantly greater fall in severity score versus placebo, and several small double-blind studies in rheumatoid arthritis and primary immunodeficiency reported mixed benefit. Effects are inconsistent, the trials are small and dated, and the mechanism was described in the literature as unknown, so the grade is best graded 2, not 3.
- FDA
- Not FDA-approved. Orphan-drug designation only (2011, sarcoidosis). Formerly marketed as Timunox in Italy (approved 1985); available as a generic in China. No EMA central approval.
- WADA
- Not prohibited
Reference only. Not medical advice.
What can go wrong
Never approved in the US or EU centrally; human data are old, small, and inconsistent, and the mechanism was not established. Largely historical outside China.
Talk to a clinician before taking this. The Atlas can tell you what has been studied about Thymopentin. It cannot tell you how it would interact with your body, your history, or anything else you are taking, and nothing on this page is a reason to start.
A synthetic pentapeptide reproducing the active fragment (residues 32 to 36) of the thymic hormone thymopoietin, formerly marketed as Timunox in Italy for immunodeficiency and still sold as a generic in China, but never FDA- or EMA-approved.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Thymopentin (TP5) is a synthetic pentapeptide corresponding to the active region of the thymic hormone thymopoietin. It modulates the maturation and function of T-cells and has a genuine pharmaceutical history as an immune modulator, distinct from the Khavinson tradition.
Thymopentin is a synthetic pentapeptide, five amino acids corresponding to the active region of the 49-amino-acid thymus hormone thymopoietin. It is one of the thymic immune peptides, alongside thymosin alpha-1 and the Russian thymic peptides, and is given by injection.
- Type
- Thymic immune peptide
- Length
- 5 amino acids
- Source
- Thymopoietin fragment
- Use
- Immune-support adjunct
- Half-life
- Very short
- Evidence
- Regional clinical
A Genuine Immune Drug, With A Short Half-Life And Regional Evidence
Thymopentin is one of the more legitimately drug-like peptides in this library, and the honesty lies in qualifying where its evidence is strong. It reproduces the immune-active part of a natural thymus hormone, promoting T-cell maturation, normalizing the balance of T-cell subsets, and helping restore thymus function suppressed by illness or drugs, with a coherent mechanism and an excellent safety record. It is genuinely used in the clinic, particularly in China and some other countries, as an immune-support adjunct for immunodeficiency, cancer chemotherapy, hepatitis B, autoimmune disease and more, and it is an active subject of cancer-immunotherapy research. Two honest qualifiers matter. Its strongest evidence comes from regional clinical practice rather than large rigorous Western trials, and its broad list of uses reflects general immune support rather than a targeted cure. It also has a very short half-life, requiring frequent injection, which has driven much research into longer-lasting formulations.
Safety in detail
Thymopentin was administered by subcutaneous or slow intravenous injection in the historical trials with generally mild reported tolerability, but it has no modern regulatory safety review in the US or EU and no contemporary human outcome data, so any current use rests on decades-old evidence.
- As a defined pentapeptide with prior clinical use, its short-term safety is better characterized than most peptides here, with injection-site and mild immune-related effects most common.
- It is not FDA-approved in the US; its approvals were in other countries and some have lapsed.
- Gray-market research material carries the usual unverified identity and purity risks.
- Long-term modern safety data is limited.
Children and teenagers
Thymopentin is used in some pediatric clinical contexts within countries where it is marketed, but it is unapproved elsewhere and should only be used under qualified medical supervision, not self-directed.
What people get wrong
Nothing recorded here yet. There is almost certainly something people get wrong about this one, and the blank space means we have not written it down, not that the record is clean.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
Thymopentin is a marketed pharmaceutical in several countries, prominently China, where it is a familiar immune-support adjunct, and it reaches Western users mainly through import and gray-market channels. Its economy is regional clinical medicine plus growing research interest in cancer immunotherapy.
How we got here
Thymopentin is a synthetic pentapeptide corresponding to the active site (residues 32 to 36) of the natural thymic hormone thymopoietin, with the sequence Arg-Lys-Asp-Val-Tyr. It was marketed as an immunomodulator under the brand name Timunox, introduced in Italy in 1985. In the United States it received only orphan drug designation rather than full approval.
Thymopentin was developed in the 1980s as the synthetic active fragment of the thymus hormone thymopoietin, becoming an established immune-modulating medicine used clinically, especially across Asia, and more recently a subject of cancer-immunotherapy research aimed at restoring thymus function and T-cell vigor.
The numbers behind the grade
- Type
- Pentapeptide (TP5)
- Origin
- Thymopoietin fragment
- Target
- Immune (T-cells)
- FDA
- Not approved (US)
- History
- Marketed abroad
- Status
- Declining use
The people taking it
A genuine older immunomodulatory drug rather than a wellness peptide, less prominent today but historically significant in thymic-peptide pharmacology.
Thymopentin’s users are patients and clinicians in countries where it is marketed, especially for immune support during cancer treatment and infection, plus immune-focused users abroad who import it.
Historically used in some countries as an immune modulator for immunodeficiency and as a vaccine adjuvant; now uncommon, and sold internationally mainly as a research peptide.
Set against the alternatives
Thymopentin sits with the thymic immune peptides, most closely thymosin alpha-1, which is approved in many countries, and the Russian thymic peptides Thymalin and Thymogen. Among these it is one of the more conventionally drug-like, a defined synthetic pentapeptide with real clinical use, though like the others its rigorous Western evidence is thinner than its clinical adoption. Its short half-life sets it apart as the one most hampered by rapid breakdown.
What we do not know
- Whether thymopentin has a continuing clinical role given newer immunomodulators.
- How its older trial evidence holds up by modern standards.
- Whether any approved indication remains active in major markets.
Legal status
Not FDA-approved in the United States. Thymopentin was approved and marketed in some countries (for example as Timunox) for immune indications, though its use has waned. Internationally it appears as a research-use-only peptide. Any legitimate use would be through the regulated channels of the countries where it remains approved.
Status current as of July 2026. Regulatory positions change, sometimes quickly.
The market for this
What follows describes how this is bought and sold. It is not a buying guide and it is not an endorsement of any seller.
Where it remains approved, through regulated pharmacies in those countries; otherwise only as a research-use-only peptide, which is not for human use. There is no FDA-approved US route.
Where still approved, it comes through regulated pharmaceutical channels; otherwise it is sold as research-use-only material, often synthesized in China, with the usual quality caveats.
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Thymopentin.
- Timeline. We have not built the dated record of research and regulatory events.
- Supply chain. We have not mapped where it is made.
- What could change. No forward-looking summary yet.
Sources
Double-blind placebo-controlled RCT in 100 atopic dermatitis patients found thymopentin (Timunox) reduced clinical severity significantly more than placebo over 6 weeks
Stiller MJ et al., J Am Acad Dermatol 1994 (double-blind placebo-controlled trial)
Earlier controlled study reported thymopentin therapy reduces the clinical severity of atopic dermatitis
Leung DY et al., J Allergy Clin Immunol 1990 (PubMed 2185294)
Thymopentin (TP-5) improved clinical parameters and lymphocyte subpopulations in atopic dermatitis
Double-blind placebo-controlled randomised study of slow intravenous thymopentin in active rheumatoid arthritis
Compilation of short- and long-term clinical studies of thymopentin (TP-5) in rheumatoid arthritis
Thymopoietin pentapeptide treatment of primary immunodeficiencies produced mixed clinical and immunological responses (open-label case series)
Thymopentin has an immunomodulatory role with a mode of action described as unknown, underscoring uncertain evidence
Thymopentin structure (Arg-Lys-Asp-Val-Tyr), history, Timunox trade name, Italy marketing, ATC L03AX09, and lack of US/EU central approval
Timunox (thymopentin) was studied in HIV-infected patients (registered clinical trial), reflecting historical AIDS-era immune use
Thymopentin substance record in FDA precisionFDA/GInAS substance registry
The studies that matter
Clinical immunomodulation studies1980s-1990s
Thymopentin was studied and marketed in some countries (as Timunox) for immune deficiencies, rheumatoid arthritis and as a hepatitis B vaccination adjuvant, with real, if dated, clinical literature.
Modern uselimited
Its use has declined and it is not FDA-approved in the US, but unlike most bioregulators it has a defined sequence and a real pharmacologic record.