Thymopentin
Thymopentin (TP-5)
Thymopentin (TP-5) is a synthetic pentapeptide (Arg-Lys-Asp-Val-Tyr) derived from thymopoietin, a hormone produced by the thymus gland. It is primarily used as an immunomodulatory agent to restore or enhance T-lymphocyte function in conditions characterized by immune deficiency, including HIV/AIDS, chronic hepatitis B and C, and certain autoimmune conditions. Clinically investigated and used in several countries as an adjunct therapy to improve cellular immunity in immunocompromised patients.
Mechanism of Action
Thymopentin binds to specific receptors on pre-T lymphocytes and promotes their differentiation and maturation into functional T-cell subsets, particularly increasing CD4+ helper T cells and restoring CD4/CD8 ratios. It stimulates the production of lymphokines including interleukin-2 (IL-2) and interferon-gamma, enhancing cellular immune responses while also exhibiting selective suppressive effects on overactive immune responses in autoimmune contexts. Its action mimics the native thymopoietin molecule at residues 32–36, which are responsible for immunological activity.
Evidence by Health Goal(16 goals)
Dosing Protocols
Subcutaneous injection, typically in the morning
Cycle: 4-8 weeks on, 4 weeks off; may repeat cycles based on clinical response
Standard clinical protocol uses 1mg subcutaneously three times per week. Some protocols use daily 1mg injections for acute immunosuppression. Reconstitute lyophilized powder in bacteriostatic water per manufacturer guidelines. Rotate injection sites. Total weekly dose typically does not exceed 3mg.
Safety & Side Effects
Thymopentin has a generally favorable safety profile in clinical studies with decades of use in Asia and Europe, where it is approved as a pharmaceutical drug; however, it is not FDA-approved in the United States and is available only as a research compound in many Western countries. Use in autoimmune conditions requires careful monitoring, as immune stimulation could theoretically exacerbate certain autoimmune diseases.
Possible Side Effects
- !Local injection site reactions including redness, mild swelling, and transient pain
- !Transient low-grade fever within hours of injection
- !Mild fatigue or flu-like symptoms during initial treatment phase
- !Headache, typically mild and self-resolving
- !Skin rash or urticaria in hypersensitive individuals
- !Rare hypersensitivity or anaphylactic reactions with repeated dosing
- !Transient lymphocyte count fluctuations during treatment initiation
Interactions
- -May potentiate the immunostimulatory effects of thymosin alpha-1 or other thymic peptides — avoid concurrent use without clinical supervision
- -Could theoretically reduce efficacy of immunosuppressive drugs (corticosteroids, cyclosporine, tacrolimus) by opposing their mechanism
- -May enhance antiviral immune responses when used adjunctively with antiviral medications for hepatitis B/C or HIV — a potential benefit but requires monitoring
- -Use caution in patients on anticoagulants, as injection site reactions may be exaggerated in those with bleeding disorders
- -Potential additive immunomodulatory effects when combined with low-dose naltrexone (LDN) — clinical significance unclear
Cost & Where to Buy
Cost reflects research-grade lyophilized peptide from reputable vendors dosed at 1mg three times per week (~12-13mg per month). Pharmaceutical-grade versions available in China (Thymopentin for Injection) are significantly cheaper domestically but import costs raise prices. Purity and vendor quality vary considerably in the research market.
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