LA LABResearch Reference Document
Compound Guide
Thymosin Alpha-1 (TA1) — Thymalfasin / Zadaxin
Quick Start
Approved in 35+ Countries — Not FDA Approved
Thymosin Alpha-1 (synthetic form: thymalfasin; brand name Zadaxin) is approved in more than 35 countries including China, Italy, and various Asia-Pacific nations for Hepatitis B and C treatment, and as an adjunct in cancer therapy and sepsis. It is NOT FDA-approved in the US. FDA placed it in Category 2 (September 2023), then removed it (September 2024), with PCAC review December 2024.
What It Is
Thymosin Alpha-1 is a 28-amino acid peptide naturally produced by the thymus gland. It is the first thymosin fraction described to have significant immunomodulatory activity. The synthetic form (thymalfasin) is identical to the naturally occurring peptide and is the active ingredient in Zadaxin. It acts as a biological response modifier — enhancing immune function rather than suppressing it.
Research Dosing
1.6 mg SubQ twice weekly (e.g. Monday and Thursday). The standard 6-month HBV protocol uses this dose continuously. For immune support research, some protocols use 1.6 mg 2–3× per week for 4–12 weeks. No ramp-up required.
Regulatory Status
Approved in 35+ countries for HBV, HCV, and cancer adjunct. NOT FDA-approved. FDA removed from Category 2 September 2024; PCAC reviewed December 2024. TESTS BMJ 2025 trial showed negative primary endpoint for sepsis. Not on WADA prohibited list. For research purposes only in the US and SA context.
Dosing Protocol
| Protocol | Dose | Frequency | Duration | Context |
|---|---|---|---|---|
| HBV Standard (Zadaxin) | 1.6 mg | Twice weekly (Mon + Thu) | 6 months | Approved clinical protocol for hepatitis B |
| Immune research | 1.6 mg | 2–3× weekly | 4–12 weeks | General immune-modulation research |
| Adjunctive | 1.6 mg | Twice weekly | With active protocol | Used alongside other treatments in international approved contexts |
Supplies & Reconstitution
Reconstitution Math — 5 mg Vial (3 mL BAC)
| Target Dose | Units (U-100) | Doses / Vial |
|---|---|---|
| 0.5 mg | 30.0 units | 10 |
| 1 mg | 60.0 units | 5 |
| 1.6 mg | 96.0 units | 3.1 |
Reconstitute the 5 mg vial with 3.0 mL bacteriostatic water (sold separately) → 1.67 mg/mL. U-100 syringe = 100 units per mL. Swirl gently — do not shake. Refrigerate 2–8°C.
Reconstitution Steps
01
Warm the vial
Remove from freezer 10–15 minutes before reconstitution. Allow to reach room temperature.
02
Swab both stoppers
Wipe the tops of both vials with fresh alcohol swabs. Air-dry.
03
Draw and inject BAC water
Draw BAC water and let it run slowly down the inside wall of the peptide vial. Do not jet onto the powder cake.
04
Swirl gently
Swirl until clear. Solution should be colourless to faint yellow. Do not shake.
05
Refrigerate
Store at 2–8°C for up to 30 days. Do not freeze after reconstitution. Protect from light.
Mechanism of Action
TLR Signalling
Activates Toll-like receptor 2 (TLR2) and TLR9 signalling on dendritic cells and plasmacytoid DCs. This triggers innate immune activation, type-I interferon production, and bridges innate to adaptive immunity.
T-Cell Activation (Th1 Shift)
Promotes differentiation and maturation of T-helper 1 (Th1) cells, and augments cytotoxic T-lymphocyte (CTL) activity. Key mechanism for its antiviral effects in HBV and HCV research. Shifts immune response toward cellular immunity.
Dendritic Cell Maturation
Promotes dendritic cell maturation and antigen-presenting function. Mature DCs are required for effective T-cell priming, relevant to both viral clearance and adjuvant cancer therapy research contexts.
No Immunosuppression
Unlike corticosteroids or calcineurin inhibitors, TA1 does not suppress immune function. It is a biological response modifier — it enhances responses that are deficient rather than globally suppressing inflammation.
Key Research
| Study / Trial | Design | Finding |
|---|---|---|
| Multiple RCTs (Zadaxin era) | HBV and HCV; 26–52 weeks | HBeAg seroconversion and HBV DNA suppression in multiple trials; approved basis in 35+ countries |
| Cancer adjunct studies | Lung, colon, breast cancer + chemo | Improved immune recovery post-chemotherapy in multiple open-label and controlled studies |
| TESTS trial (BMJ 2025) | RCT; n=1,100+; sepsis; 28-day mortality | Primary endpoint not met — no significant mortality difference vs placebo in sepsis |
| COVID-19 research | Observational; China 2020 | Suggested reduced mortality in severe COVID-19; not confirmed in RCTs |
Storage
| State | Temperature | Duration | Notes |
|---|---|---|---|
| Lyophilised (powder) | −20°C (freezer) | Up to 24 months | Protect from light and moisture |
| Reconstituted (liquid) | 2–8°C (refrigerator) | Up to 30 days | Do not freeze after reconstitution |
| Short-term (travel) | <25°C | Up to 72 hours | Avoid heat and direct sunlight |
Disclaimer
This document is an educational research reference only. Thymosin Alpha-1 is not FDA-approved in the United States. Approved uses in other jurisdictions (HBV, HCV, cancer adjunct) require supervision by a qualified medical professional. By purchasing from LA LAB you confirm you are 18+ and that products are for research purposes only.
Side Effects & Clinical Data
Thymosin alpha-1 is an approved medicine in over 30 countries as Zadaxin, used for hepatitis B and C and as an immune adjuvant. That gives it a real safety record — better than almost anything else on this list.
| Reported | Detail |
|---|---|
| Injection-site reactions | The most common finding in trials — redness, discomfort. |
| Transient fatigue | Reported; usually brief. |
| Mild flu-like symptoms | Occasionally reported in the first doses, consistent with immune activation. |
| Joint or muscle ache | Uncommon. |
Trials generally describe thymosin alpha-1 as well tolerated, with a side-effect profile far milder than interferon, which it was often studied alongside.
Who Should Avoid Thymosin Alpha-1
| Situation | Why |
|---|---|
| Organ transplant recipients, or anyone on immunosuppressants | Avoid. Thymosin alpha-1 stimulates immune function — directly against the purpose of anti-rejection treatment. |
| Autoimmune disease | Caution. Stimulating an immune system that is already attacking the body is not obviously wise, and has not been studied. |
| Pregnancy or breastfeeding | Avoid. No data. |
| Under 18 | Use in children has been in specific supervised clinical settings, not for general immune support. |
Frequently Asked Questions
Is this actually an approved medicine?
Yes — as Zadaxin, in more than 30 countries, mainly for chronic hepatitis B and C and as a vaccine adjuvant. It is one of the few compounds here with genuine regulatory approval somewhere.
Yes — as Zadaxin, in more than 30 countries, mainly for chronic hepatitis B and C and as a vaccine adjuvant. It is one of the few compounds here with genuine regulatory approval somewhere.
Does it boost immunity generally?
It modulates T-cell function, and the evidence is in specific conditions studied in trials. “General immune support” in a healthy person is an extrapolation, not a trial result.
It modulates T-cell function, and the evidence is in specific conditions studied in trials. “General immune support” in a healthy person is an extrapolation, not a trial result.
Was it used for COVID?
It was studied during the pandemic, with mixed results, mostly in China. Nothing definitive came of it.
It was studied during the pandemic, with mixed results, mostly in China. Nothing definitive came of it.
How long does a course run?
Clinical protocols for hepatitis ran for months. Shorter community courses are extrapolation.
Clinical protocols for hepatitis ran for months. Shorter community courses are extrapolation.
Can I take it if I have an autoimmune condition?
Speak to a prescriber first. Stimulating immune function when your immune system is already the problem needs proper advice.
Speak to a prescriber first. Stimulating immune function when your immune system is already the problem needs proper advice.
Does it interact with vaccines?
It has been studied deliberately as a vaccine adjuvant, which is an argument for interaction rather than against.
It has been studied deliberately as a vaccine adjuvant, which is an argument for interaction rather than against.
Sources & Research
Garaci E et al. Thymosin α1: from bench to bedside. Ann N Y Acad Sci 2007;1112:225–34.
Chien RN et al. Efficacy of thymosin α1 in patients with chronic hepatitis B: a randomized, controlled trial. Hepatology 1998;27:1383–7.
Matteucci C et al. Thymosin α1 and HIV-1: recent advances and future perspectives. Future Microbiol 2017;12:141–155.
Regulatory status — approved as Zadaxin in more than 30 countries. Not approved by SAHPRA or the FDA.
Educational reference only
This document is a research reference, not medical advice and not a treatment plan. Thymosin alpha-1 is approved in over 30 countries for specific conditions, but not by SAHPRA or the FDA. Dose decisions belong to you and your prescriber. Independent certificates of analysis for every LA LAB batch are published under Research → Lab Results, with the Janoshik task number and verification key so you can check them yourself.