Thymalin
Also known as: thymus polypeptide fraction
Thymalin is a calf-thymus polypeptide complex proposed to act as an immunomodulator that promotes T-lymphocyte differentiation and maturation and normalizes cytokine and immune-cell balance, though its precise molecular receptor or target remains undefined.
- Drug class
- Thymic peptide bioregulator (immunomodulator / polypeptide extract)
- Primary targets
- T-lymphocyte differentiation and maturation, thymic and immune homeostasis, cytokine regulation (IL-2, interferon), hematopoietic stem cell differentiation
- Dose reference
- Reference only, not a recommendation: Russian trials/labeling describe roughly 5-20 mg intramuscularly daily for short 5-10 day courses; the 2021 COVID-19 trial used 10 mg IM daily for 10 days.
- Half-life
- Not well characterized; short peptide complex with a presumed short plasma half-life (dosing relies on repeated daily courses).
- Developer / origin
- V. G. Morozov and V. Kh. Khavinson (Military Medical Academy / St. Petersburg Institute of Bioregulation and Gerontology, USSR/Russia)
- Reference year
- 1980
- Evidence score
- 2/5 - Limited / low-quality human evidence dominated by a single research lineage
Limited / low-quality human evidence dominated by a single research lineage
Thymalin has a large but narrow evidence base: plausible laboratory immune-modulation data and some controlled human studies, but the major aging and mortality claims come from observational, mostly Russian-language work by the compound's own developers and lack independent large blinded Western replication.
Mostly animal, ex vivo, cell, or indirect evidence.
Evidence basis
- 1997 Int J Immunopharmacol review (Morozov & Khavinson): thymic peptides isolated from calf thymus activate T-cell differentiation and alter lymphocyte cytokine output
- 2020 Bull Exp Biol Med study: Thymalin shifted human hematopoietic stem cell markers (lower CD44/CD117, higher CD28) toward mature T cells in culture
- 2003 Neuro Endocrinol Lett / 2002 Adv Gerontol: 266 elderly, open observational program, reported ~2.0-2.1-fold (up to 4.1-fold in a subgroup) mortality reduction, not blinded or randomized
- 2021 Adv Gerontol randomized single-blind COVID-19 trial (n=36 vs 44): faster lymphocyte recovery, larger IL-6 drop, lower in-hospital mortality (19.4% vs 40.9%); single-center, small, authors flag limits
- No independent large multi-center blinded Western RCTs; not FDA-approved; extract of undefined exact composition
Key references
- PubMed / Int J Immunopharmacol 1997Natural and synthetic thymic peptides as therapeutics for immune dysfunction
- PubMed / Neuro Endocrinol Lett 2003Peptides of pineal gland and thymus prolong human life
- PMC / Advances in Gerontology 2021Peptide Drug Thymalin Regulates Immune Status in Severe COVID-19 Older Patients
- PMC / Bull Exp Biol Med 2020Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells
How to read this entry
Dose references and half-life values are pulled from trial protocols, labels, reviews, or published summaries where available. They are context for research and comparison, not a personal dosing recommendation.
Status matters: approved drugs have regulated indications; investigational compounds are still being studied; research-only peptides do not have established human dosing, safety, or efficacy for consumer use.
Thymalin guides
Read the matching guide or adjacent research pages for more context.
Peptide calculators
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