Educational reference only. Not medical advice. Consult a healthcare provider before starting any protocol.
Thymulin
Thymulin (Facteur Thymique Sérique / FTS / Nonathymulin)
What it is
A naturally occurring zinc-dependent nonapeptide (pyroGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn) produced by thymic epithelial cells. Originally characterized by Jean-François Bach and Mireille Dardenne at INSERM, Paris, in 1977. Thymulin requires equimolar zinc binding for biological activity — the zinc-free form (FTS) is inactive. It has been studied in animal models for T-cell differentiation, NK cell enhancement, anti-inflammatory effects, and neuroendocrine signaling. Limited human clinical data exists from two double-blind, placebo-controlled trials in rheumatoid arthritis. Circulating thymulin levels decline with age, correlating with thymic involution. Not approved as a drug in any major market.
Community-reported ranges
Dosing sourced from published clinical trial protocols (Amor et al., 1987) and community forums. Zinc co-supplementation is discussed alongside thymulin use due to its zinc-dependent activity. This is not dosing guidance.
Reported dose range
5000–5000 mcg
Estimated half-life
~10 minutes
Source: animal pharmacokinetic data (IV sheep model)
Reported cycle length
4–12 weeks on
4-8 weeks off
Route
subcutaneous
Common vial sizes
5mg, 10mg
Reported timing
AM
Reported frequency
1x daily (clinical trial protocol)
Frequently discussed alongside
Based on community forum discussions. Not a recommendation to combine compounds.
Published research
Bach and Dardenne published the foundational characterization of thymulin in Nature in 1977. Two randomized, double-blind, placebo-controlled trials in rheumatoid arthritis (Amor et al., 1987) tested three dose levels, with 5 mg/day showing 56% significant clinical improvement vs. 17% for placebo (p<0.02). Preclinical research has demonstrated T-cell differentiation induction, NK cell enhancement, cytokine modulation (reduction of TNF-α, IL-1β, IL-6 in inflammatory models), and bidirectional thymus-pituitary neuroendocrine communication. Development by Santen Pharmaceutical for RA and ischemic heart disease was discontinued. More recently, gene therapy approaches using metFTS analogs and the synthetic analog PAT (Peptide Analog of Thymulin) have been explored in preclinical models.
Bach et al. — Biochemical characterisation of a serum thymic factor
Nature
Amor et al. — Nonathymulin in rheumatoid arthritis: two double blind, placebo controlled trials
Annals of the Rheumatic Diseases
Reggiani et al. — Physiology and therapeutic potential of the thymic peptide thymulin
Current Pharmaceutical Design
Reported side effects
From community self-reports. Not from controlled studies.
Clinical trial data from two double-blind RA trials reported minimal adverse effects. Animal studies described thymulin as non-toxic at very large doses. An important pharmacological note: thymulin exhibits dose-dependent behavior — low nanogram doses may cause hyperalgesia via PGE2 pathways, while higher doses exert anti-inflammatory effects. Systematic long-term safety data in humans is extremely limited.
Regulatory status
FDA (United States)
Not approved for any indication. Listed as 'Investigational' on the NCATS Inxight Drugs database. No active IND is publicly known.
Health Canada
Not authorized as a therapeutic product. No DIN or NPN assigned.
WADA (Competitive Athletes)
Not specifically named on the WADA Prohibited List. As an unapproved substance, it potentially falls under S0 (Non-Approved Substances). Athletes should consult anti-doping authorities.
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