Thymalin

Thymalin is a polypeptide complex from calf thymus - in other words, a mixture of short peptides (protein messengers) obtained from the thymus (an organ behind the breastbone that is central to immune maturation). It was developed in 1971 by Vladimir Khavinson at the Military Medical Academy in Leningrad (now St. Petersburg) and has been on the market in Russia as an approved medication since 1982 [1]. Unlike Thymosin Alpha-1, which is a single, precisely defined peptide with 28 amino acids, Thymalin consists of a whole cocktail of different short peptides - the active fragments include the dipeptides KE (Lys-Glu) and EW (Glu-Trp) as well as the tripeptide EDP (Glu-Asp-Pro) [8].

How is Thymalin used?

Thymalin is injected intramuscularly - this is the route documented in all clinical studies and in the Russian drug label [2][6]. The lyophilisate (freeze-dried powder) is dissolved in 1-2 mL of 0.9% saline solution before injection and administered immediately; the reconstituted solution must not be stored [6].

In gray market practice (i.e., outside Russian pharmacies, in the international research chemicals market), Thymalin is also administered subcutaneously with insulin syringes. However, there are no controlled studies for this route - all published human data refer to intramuscular administration [7]. There is no oral, nasal, or sublingual form with proven effectiveness.

Typical regimen in studies and in the Russian label: 5-10 mg per day intramuscularly for 5-10 consecutive days, repeated after 1-6 months if needed [2][6]. In the geroprotective (anti-aging) context, the course is repeated 1-2 times per year, sometimes in combination with the pineal peptide Epithalamin [3].

From vial to use: Reconstitution and calculation

Thymalin is typically supplied as 10 mg lyophilisate per vial [6]. The documented reconstitution method is:

• Solvent: 1-2 mL of 0.9% saline solution (NaCl) - preferred over BAC water according to the Russian label [6]
• Concentration at 1 mL: 10 mg/mL - a 10 mg dose then corresponds to 1.0 mL = 100 units on a U-100 insulin syringe
• Concentration at 2 mL: 5 mg/mL - a 5 mg dose then corresponds to 1.0 mL = 100 units; a 10 mg dose corresponds to 2.0 mL = 200 units (note: this volume is unusually high for a subcutaneous injection; clinically, it is injected i.m.)
• Storage: Lyophilisate at 2-8 °C; use the reconstituted solution immediately, do not store [6]

For mixing and calculating the correct dose, you can follow the step-by-step guides. If you want to calculate a specific dose from a vial, the injection calculator can help - but note that Thymalin is clinically administered intramuscularly and the subcutaneous gray market practice has no controlled study basis.

How does Thymalin work?

Thymalin acts as an immunomodulator - it regulates the immune system without simply "boosting" it. The short peptides in Thymalin (KE, EW, EDP) can specifically bind to double-stranded DNA and histones (proteins around which DNA is wrapped) and thus control gene expression [8]. Simply put: Thymalin switches genes on or off that are important for the production of immune proteins.

Specifically, Thymalin does the following in studies:

• T-cell maturation: Precursor cells develop into functional T-lymphocytes (CD28+), and the CD4/CD8 ratio normalizes [4][8]
• NK-cell activation: Natural killer cells, which recognize virus-infected and tumorous cells, become more active [2]
• Stem cell differentiation: Hematopoietic (blood-forming) stem cells are stimulated to mature [4]
• Inflammation reduction: IL-6 and TNF-alpha (pro-inflammatory messengers) are lowered - relevant, for example, in the so-called "cytokine storm" in severe COVID-19 [2]

A special aspect: The active ingredient EW (Glu-Trp) also inhibits ACE2 - the enzyme that SARS-CoV-2 uses as an entry point. This explains why Thymalin was specifically studied in COVID-19 [8].

What is proven in human studies?

The human evidence for Thymalin focuses on several areas:

COVID-19 (RCT, 2021): In a randomized controlled study, 36 elderly patients with severe COVID-19 received 10 mg Thymalin/day i.m. for 10 days in addition to standard therapy, compared with 44 patients who received only standard therapy + placebo. The Thymalin group showed faster recovery of lymphocytes, NK cells, and inflammatory markers (CRP, D-dimer) - and hospital mortality was roughly halved [2].

Lifespan extension (long-term study): Khavinson et al. studied elderly patients over 6-12 years who received annual courses of Thymalin (alone or combined with Epithalamin, a pineal peptide). Mortality was reduced by a factor of 2.0 (Thymalin alone) or 2.5 (combination) compared to the control group [3].

Stem cell activation (2020): In vitro with human hematopoietic stem cells, it was shown that Thymalin activates their differentiation [4].

Early clinical studies (from 1982): The initial publication documented immunomodulation in various immunopathologies, including patients after radiation therapy and with chronic infections [1]. Further studies examined Thymalin in treatment-resistant schizophrenia [5], chronic hepatitis, herpes, and HIV (as adjunctive therapy).

Thymalin vs. other thymus peptides - what's the difference?

Thymalin is often confused with other thymus peptides, but it is structurally and functionally different:

The key difference: Thymalin is a mixture of several short peptides and therefore acts more broadly, but is also less precisely definable than a single peptide like Thymosin Alpha-1. The doses of the different thymus peptides are not interchangeable.

Side effects and risks

The following side effects are reported in the published studies:

• Local reactions at the injection site: redness, pain, mild swelling [2]
• Contraindications according to the Russian label: pregnancy, breastfeeding, individual hypersensitivity to thymus preparations [6]

There are no systematic long-term safety data outside the Russian studies. Data on dose adjustments for kidney or liver dysfunction are also lacking [6]. Subcutaneous use in the gray market has not undergone any controlled safety evaluation [7].

What is NOT known?

• Independent replication: Almost all human studies come from Khavinson and colleagues at the St. Petersburg Institute of Bioregulation and Gerontology. Western, independent replication studies are missing.
• No FDA/EMA approval: Thymalin is not approved as a medication outside Russia and a few CIS states.
• No pharmacokinetics: Since Thymalin is a multi-peptide mixture, there are no published Cmax/Tmax data or half-lives for the overall complex.
• Subcutaneous use unproven: The s.c. administration common in the gray market has no controlled study basis.
• Molecular mechanism (DNA/histone binding of the short peptides) is mainly proven in vitro; the transfer to the living organism is not fully understood.

If you are interested in buying peptides on the gray market, be sure to read the notes on protection when ordering, since the quality, purity, and authenticity of gray market products are not guaranteed. For an overview of other active ingredients, check out the peptide library.