Peptide LibraryThymopentin
Thymopentin is a thymopoietin fragment in the Thymic Peptide class. Thymopentin reproduces the active site of thymopoietin, a thymic hormone involved in T-cell differentiation. It has been reported to promote maturation of T-cell precursors and to modulate the balance of T-cell subsets and cytokine production.
For research use only.
Key Facts
- CAS
- 69558-55-0
- Molecular Weight (MW)
- 679.8 g/mol
- Half-life
- —
- FDA status
- Not Approved
- Evidence level
- Clinical Trial Evidence
- Human dose established
- Yes
- Administration Route
- Subcutaneous · Intravenous (slow injection, in the rheumatoid arthritis trials)
- Frequency
- Three times a week in the published trials
- Last updated
- Nov 7, 2026
- Reviewed
- Nov 7, 2026
Research summary
Synthetic pentapeptide corresponding to residues 32 to 36 of thymopoietin, the fragment that carries its immunologically active sequence. Used in some countries as an immunomodulator; not FDA-approved.
Research evidence
- Regulatory review (FDA label)None in reviewed sources
- Controlled human trials6 reviewed sources
- Early or uncontrolled human studiesNone in reviewed sources
- Lab & animal studiesNone in reviewed sources
How it works
Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess.
Peptide Library's Thymopentin profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Thymopentin dosage evidence
Thymopentin has human dosing evidence from randomised trials of the 1980s and 1990s. The trials that state their dose used 50 mg three times a week: by slow intravenous injection for 3 weeks in rheumatoid arthritis, and by subcutaneous injection for 12 weeks in severe atopic dermatitis and for 24–52 weeks in HIV infection. Thymopentin is not FDA-approved and has no DailyMed listing.
| Human dosing established | Yes |
|---|---|
| Studied dose range | 50 mg three times a week in the published trials; 10 mg twice a week in one registered trial |
| Route | Subcutaneous · Intravenous (slow injection, in the rheumatoid arthritis trials) |
| Frequency | Three times a week in the published trials |
| Duration studied | 3 weeks (rheumatoid arthritis) to 12 weeks (atopic dermatitis) and 24–52 weeks (HIV) |
| Evidence level | Clinical Trial Evidence |
| Last reviewed | 2026-11-07 |
Research-reported dosing
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Active rheumatoid arthritis, Lancet trial (1985)Clinical trial · Randomised double-blind placebo-controlled trial | Adults with active rheumatoid arthritis (n=41; 21 thymopentin, 20 placebo) | 50 mg, given in fractions over 10 minutes | Slow intravenous injection | Three times a week | 3 weeks | Less joint tenderness, swelling and morning pain than placebo; a trend to relapse 4 weeks after stopping | Treatment of active rheumatoid arthritis with slow intravenous injections of thymopentin. A double-blind placebo-controlled randomised study. Lancet. 1985. |
| Rheumatoid arthritis, multicentre UK trial (1989)Clinical trial · Randomised placebo-controlled multicentre trial | Adults with rheumatoid arthritis (n=76) | 50 mg | Slow intravenous injection | Three times a week | 3 weeks, with follow-up to 7 weeks | Ritchie index and swollen joint score improved more than with placebo; toxicity minimal | Thymopentin (TP-5) in the treatment of rheumatoid arthritis. Br J Rheumatol. 1989. |
| Severe atopic dermatitis, adjunct to topical steroids (1994)Clinical trial · Randomised double-blind placebo-controlled trial | Patients aged 2 years and older with severe atopic dermatitis on at least 20% of the skin (n=39) | 50 mg | Subcutaneous | Three times a week | 12 weeks | Greater improvement than placebo; no thymopentin-related adverse events reported | A double-blind, placebo-controlled clinical trial to evaluate the safety and efficacy of thymopentin as an adjunctive treatment in atopic dermatitis. J Am Acad Dermatol. 1994. |
| Moderate to severe atopic dermatitis, two-centre trial (1990)Clinical trial · Randomised double-blind placebo-controlled trial | Patients with moderate to severe atopic dermatitis (n=100; 48 thymopentin, 52 placebo) | Not stated in the indexed abstract | Subcutaneous | Daily | 6 weeks | Larger fall in clinical severity score than placebo (p = 0.04), with less itching and redness | Thymopentin therapy reduces the clinical severity of atopic dermatitis. J Allergy Clin Immunol. 1990. |
| HIV infection without AIDS (1992)Clinical trial · Randomised double-blind placebo-controlled trial | HIV-positive adults without AIDS (n=91; 52 asymptomatic, 39 symptomatic) | 50 mg | Subcutaneous | Three times a week | 24 or 52 weeks | Asymptomatic patients kept more CD4+ cells than with placebo; no difference in symptomatic patients | Maintenance of CD4+ cells by thymopentin in asymptomatic HIV-infected subjects: results of a double-blind, placebo-controlled study. AIDS. 1992. |
| HIV infection treated with zidovudine (1995)Clinical trial · Randomised double-blind placebo-controlled trial | Asymptomatic HIV-positive adults on zidovudine with 200–500 CD4 cells/mm3 (n=352) | 50 mg | Subcutaneous | Three times a week | 48 weeks of evaluation | Fewer progressions to AIDS or death in people with more than 6 months of prior zidovudine; no difference in those with less | Safety and efficacy of thymopentin in zidovudine (AZT)-treated asymptomatic HIV-infected subjects with 200-500 CD4 cells/mm3: a double-blind placebo-controlled trial. J Acquir Immune Defic Syndr Hum Retrovirol. 1995. |
| NCT00460681 — phase 3, after resection of small hepatocellular carcinomaClinical trial · Phase 3 registered trial, status unknown | Patients after curative resection of small hepatocellular carcinoma (estimated n=220) | 10 mg | Subcutaneous or intramuscular | Every second day (twice a week, as the record states) | 3 months | Not reported; status unknown and no results posted | NCT00460681 — Study of Thymopentin in Patients After Curative Resection of Small Hepatocellular Carcinoma |
Where sources disagree
- The 50 mg three-times-weekly regimen is consistent across the trials that state a dose, but the route is not: rheumatoid arthritis trials gave it by slow intravenous injection, and the dermatitis and HIV trials by subcutaneous injection.
- Results were mixed. A 6-month course in chronic hepatitis B was reported as not effective (PubMed 7836705), and the 1995 HIV trial found benefit in only one of its two groups.
- The registered liver cancer trial used a different regimen (10 mg every second day for 3 months), and its record calls this both every second day and twice a week. It has posted no results.
- Thymopentin is not FDA-approved and has no DailyMed listing. The trial doses come from people with specific diseases under medical supervision; no trial studied healthy people.
Sequence & molecular data
| Amino acid sequence | Arg-Lys-Asp-Val-Tyr |
|---|---|
| Molecular formula | C30H49N9O9 |
| Molecular weight | 679.8 g/mol |
| CAS number | 69558-55-0 |
| PubChem CID | 451417 |
| ChEMBL | CHEMBL156025 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
Thymopentin reproduces the active site of thymopoietin, a thymic hormone involved in T-cell differentiation. It has been reported to promote maturation of T-cell precursors and to modulate the balance of T-cell subsets and cytokine production. Its plasma half-life is measured in minutes, which constrains dosing and complicates interpretation of its clinical effects.
Studies
- Experience with thymopentin in the treatment of periarthritis humeroscapularis, tendinitis, and gonarthrosis by local infiltration
- Thymopentin therapy reduces the clinical severity of atopic dermatitis
- Efficacy and safety of systemic treatments for moderate-to-severe atopic dermatitis: a systematic review
- Thymopentin enhances adenoviral oncolytic therapy by regulating macrophages and CD8(+) T cells
- Thymopentin: safety overview
Research statistics
511 PubMed publications · 36.8% human clinical research · 9 registered trials
Counts of published research through 2026-11-01, not evidence that it works. Publications by year, study types and trials · How publications are counted
Regulatory & research status
Thymopentin is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Research status | Research-only compound; no approval pathway listed |
| Availability | Research-Only |
| WADA (sport) | Unknown / Not Listed |
| Library classification | Research-Only |
How FDA approval, compounding and research-only status differ
Benefits
—
Thymopentin side effects
No side effects listed yet for this entry.
Storage & stability
This compound is not supplied as a powder to be mixed, so the freeze-dried powder and reconstitution handling described for research peptides does not apply. Storage conditions are product-specific: follow the label or packaging of the product itself.
Thymopentin: frequently asked questions
What is Thymopentin?
Synthetic pentapeptide corresponding to residues 32 to 36 of thymopoietin, the fragment that carries its immunologically active sequence. Used in some countries as an immunomodulator; not FDA-approved.
How does Thymopentin work?
Thymopentin reproduces the active site of thymopoietin, a thymic hormone involved in T-cell differentiation. It has been reported to promote maturation of T-cell precursors and to modulate the balance of T-cell subsets and cytokine production.
Is Thymopentin FDA approved?
No. Thymopentin is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What is the amino acid sequence of Thymopentin?
Thymopentin has the sequence Arg-Lys-Asp-Val-Tyr, giving a chain of 5 amino acids. Its molecular formula is C30H49N9O9.
What peptides are similar to Thymopentin?
Compounds most often compared with Thymopentin include Thymosin Alpha-1, Thymalin, Thymogen (Oglufanide) and Thymulin. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- Experience with thymopentin in the treatment of periarthritis humeroscapularis, tendinitis, and gonarthrosis by local infiltration — Arzneimittelforschung, 1988External reference
- Thymopentin therapy reduces the clinical severity of atopic dermatitis — J Allergy Clin Immunol, 1990External reference
- Efficacy and safety of systemic treatments for moderate-to-severe atopic dermatitis: a systematic review — J Allergy Clin Immunol, 2014External reference
- Thymopentin enhances adenoviral oncolytic therapy by regulating macrophages and CD8(+) T cells — Commun Med (Lond), 2026External reference
- Thymopentin: safety overview — Surv Immunol Res, 1985External reference
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Nov 7, 2026 · Version 2
This Thymopentin profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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