Thymosin Alpha-1
TA-1 Β· Thymalfasin Β· Zadaxin
Thymic peptide (28 AA) that modulates T-cell maturation and innate immunity. Approved as Zadaxin in 35+ countries for hepatitis B/C and used as cancer adjuvant. The most clinically validated immune-modulating peptide in practice.
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Mechanism of Action
Activates Toll-like receptors (TLR2, TLR9) on dendritic cells and macrophages, triggering innate immune responses. Promotes T-helper 1 (Th1) polarisation, increases IL-2 and IFN-Ξ³ production, enhances NK cell cytotoxicity, and stimulates thymic T-cell maturation via FOXN1 pathway. Downregulates excessive inflammatory cytokines (IL-6, TNF-Ξ±) while upregulating regulatory T-cells β net effect is immune normalisation rather than pure stimulation.
Clinical Applications
- βChronic viral infections (hepatitis B and C β RCT data; EBV, CMV, HSV recurrence)
- βPost-COVID immune dysfunction and long COVID fatigue
- βCancer adjuvant therapy β reduces chemotherapy-induced immunosuppression, improves survival in RCTs
- βRecurrent infections in immunocompromised patients
- βChronic fatigue syndrome and fibromyalgia (immune-driven phenotype)
- βAutoimmune conditions β immune normalisation (Th1/Th2 rebalancing)
- βVaccine non-responders β augments antibody titres
- βSepsis adjuvant (high-dose studied in ICU trials in China)
Dosing Protocol
Recommended Dosing
SC injection. Standard protocol: 1.6 mg twice weekly (Mon/Thu) for 6β12 weeks. Chronic/maintenance: 1.6 mg once weekly. Cancer adjuvant: 1.6 mg twice weekly during and after chemotherapy cycles. Acute viral/sepsis: 1.6 mg daily for 5β7 days (clinical supervision required). Half-life ~2 h but immunological effects persist 3β7 days. Reconstitute with bacteriostatic water; stable 30 days refrigerated.Safety & Contraindications
Possible Side Effects
- β Injection site reactions (mild erythema, induration β most common, resolves within 24 h)
- β Transient fatigue or flu-like symptoms in first 1β2 weeks (immune activation response)
- β Rarely: headache, dizziness
- β No serious adverse events reported across 30+ RCTs at standard doses
Contraindications
- βSolid organ transplant recipients on immunosuppression β risk of rejection by immune potentiation
- βActive autoimmune disease with Th1-dominant phenotype (e.g. MS relapse, active rheumatoid arthritis flare) β use with caution, may worsen
- βPregnancy (insufficient safety data)
- βUse with caution alongside immunosuppressive drugs β pharmacodynamic interaction