Thymosin Alpha-1: Immune Peptide Benefits, Dosage, Evidence, Regulatory Status

Key takeaways

• Thymosin alpha-1 is a 28-amino-acid peptide first isolated from a calf-thymus extract in 1977. Its synthetic form, thymalfasin, is sold outside the US as Zadaxin and is approved in a number of countries, mainly for chronic hepatitis B and as a flu-vaccine adjuvant. It has never been approved in the United States.
• The trial record is long and mostly weak. Hepatitis B results conflict, and a 2026 Cochrane review rated that evidence low to very low certainty. The largest and best trial ever run, in 1,106 adults with sepsis, found no survival benefit. COVID-19, melanoma and liver-cancer data are small, open-label or retrospective.
• What it is marketed for in the US, from general 'immune support' to Lyme disease, chronic fatigue and long COVID, has no clinical trial behind it. FDA looked for studies in Lyme disease and chronic fatigue in 2024 and found none.
• The studied dose is 1.6 mg under the skin, twice a week for months in hepatitis or every 12 hours for a week in sepsis. Trials report mostly injection-site discomfort, but labels abroad rule it out in pregnancy and in transplant patients on immunosuppression, and urge caution in autoimmune disease.
• No US pharmacy may legally compound it. FDA placed it in Category 2 in 2023, reviewed it anyway after the nomination was withdrawn, and proposed keeping it off the permitted list; its advisory committee agreed, 17 to 4, on December 4, 2024.

Thymosin alpha-1 at a glance

Also called

thymalfasin, Zadaxin (brand sold outside the US), Ta1, TA-1

Class

Synthetic copy of a 28-amino-acid peptide first isolated from calf thymus; the N-terminal piece of the protein prothymosin alpha; an immunomodulator

Route

Subcutaneous injection; in trials usually 1.6 mg twice a week (hepatitis) or every 12 hours for a week (sepsis)

FDA status

Never approved in the US (four orphan-drug designations, which are not approvals). Placed in Category 2 in 2023; after the nomination was withdrawn, FDA reviewed it on its own initiative, proposed not to add it to the 503A bulks list, and its advisory committee voted 17 to 4 against on December 4, 2024. No final rule as of October 2026.

FDA Category 2 (compounding restricted)

No

Available by prescription (US)

No. It is not FDA-approved, has no USP monograph, is not part of an approved drug and is not on the 503A bulks list, so no licensed pharmacy may compound it

Best-studied use

Chronic hepatitis B and C (with interferon), vaccine response in older and dialysis patients, sepsis, COVID-19, and as an add-on in melanoma and liver cancer; approved abroad mainly for hepatitis B and as a flu-vaccine adjuvant

Typical monthly cost (telehealth, 2026)

No legal US price; products sold in the US are unapproved compounded or research-labeled preparations

What thymosin alpha-1 is and how it works

Researchers looking for the signals that let the thymus train T cells worked with a crude extract of calf thymus called thymosin fraction 5. Thymosin alpha-1 was one of the peptides purified from it, in 1977: an acidic chain of 28 amino acids with an acetyl group on the first one (FDA 2024). It turned out not to be a thymus-only hormone. It is the front end of a larger protein, prothymosin alpha (the genetics are in our comparison with TB-500), and it has been detected in the spleen, lung, kidney, brain and blood as well as the thymus; healthy adults carry about 0.1 to 1 ng/mL in their serum.

Thymalfasin is the same sequence made by chemical synthesis, and Zadaxin is the finished product sold abroad, a 1.6 mg vial for injection under the skin. In laboratory and animal work, thymosin alpha-1 acts largely through toll-like receptor 9 on dendritic cells and immature lymphocytes, pushing them toward antigen presentation and T-cell responses, while a feedback enzyme called IDO may keep inflammation in check (FDA 2024). Hence 'immunomodulator' rather than 'stimulant'. FDA's reviewers added a caution: most animal doses were far above human doses.

A 1.6 mg injection raises blood levels about tenfold within an hour, and they fall back near baseline within a day; the half-life is roughly 1.5 hours (Wu 2025).

Despite the name, thymosin alpha-1 has nothing structural in common with thymosin beta-4, the protein behind the healing peptide sold as TB-500. Our comparison, thymosin alpha-1 vs TB-500, explains the difference, and the TB-500 profile covers the other molecule.

Where it is approved, and where it is not

Regulator listings that FDA collected for its 2024 review show thymosin alpha-1 authorized in Italy as an adjuvant to flu vaccination in immunocompromised people, in India, Indonesia and Mexico for chronic hepatitis B, in Singapore for chronic hepatitis B and C, and in Hong Kong (FDA 2024). The manufacturer has claimed wider approvals across Asia, Latin America, Eastern Europe and the Middle East, which FDA could not verify. The European Medicines Agency has granted only an orphan designation, for liver cancer, which is not a marketing authorization.

In the United States it holds four orphan-drug designations, incentives to study a drug in a rare disease. None is an approval, and nothing containing thymosin alpha-1 has ever been approved here.

What the evidence actually shows

Thymosin alpha-1 has more human trials behind it than almost any peptide sold for wellness, which makes the pattern easy to see: positive signals in small, often unblinded studies, and much less once the trials became larger, blinded and modern.

Thymosin alpha-1 claims, graded by the evidence behind them

Claim	Grade	What the evidence shows	Sources
Clears chronic hepatitis B	B	Mixed. In 98 Taiwanese patients, 1.6 mg twice weekly for 26 weeks cleared viral DNA and e antigen in 40.6% versus 9.4% of untreated controls at 18 months. The double-blind US Phase 3 in 97 patients found 14% versus 4%, not significant. A 2026 Cochrane review of 10 trials (1,349 people) rated the evidence low to very low certainty.	Chien 1998; Mutchnick 1999; Naing 2026
Improves hepatitis C treatment	B	Added to interferon in 109 patients, end-of-treatment enzyme response was 37.1% versus 16.2%, but sustained response only 14.2% versus 8.1%. In 552 earlier non-responders on peginterferon and ribavirin, sustained cure was 12.7% versus 10.5%, not significant. Both regimens are obsolete.	Sherman 1998; Ciancio 2012
Strengthens flu-vaccine response in older or dialysis patients	C	In 90 men aged 65 to 99, a four-fold antibody rise occurred in 69% versus 52% on placebo, mostly among men 77 and older. A 99-patient open-label dialysis study found higher titers. Antibodies only: no trial counted flu illness, hospital stays or deaths.	Gravenstein 1989; FDA 2024
Effect on survival in sepsis	A	No benefit. In 1,106 intensive-care adults given 1.6 mg every 12 hours for 7 days or placebo, 28-day deaths were 23.4% versus 24.1% (hazard ratio 0.97) and 90-day deaths 31.0% versus 32.4%. Age and diabetes subgroups differed, which only a new trial can test.	Wu 2025
Reduces COVID-19 deaths	C	A retrospective series of 76 severe patients in Wuhan reported 11.1% versus 30.0% mortality, but a meta-analysis of 9 mostly observational studies with 5,352 patients found no effect (risk ratio 1.03). One 105-patient double-blind trial reported 3 of 27 versus 5 of 13 deaths among severe patients.	Liu 2020; Shang 2023; Shetty 2022
Extends survival in metastatic melanoma	B	488 patients on dacarbazine with or without interferon: more tumor responses in two thymosin arms, median survival 9.4 versus 6.6 months (hazard ratio 0.80, P = 0.08), not significant. The control regimen is no longer used.	Maio 2010; FDA 2024
Helps in liver cancer	C	A 25-patient randomized trial with chemoembolization found no significant difference in response (57.1% versus 45.5%) or survival. Retrospective studies after surgery report better survival but cannot separate the drug from who was chosen to receive it.	Gish 2009; FDA 2024
Immune support, Lyme disease, chronic fatigue, long COVID	D	No clinical studies. FDA found none in Lyme disease or ME/CFS in 2024; the long COVID work we found is laboratory testing of patients' blood cells. No trial has given it to healthy adults for immune support.	FDA 2024

Hepatitis B and C: the original uses, now overtaken

In Taiwan, 98 adults with chronic hepatitis B were randomized to 1.6 mg under the skin twice a week for 26 weeks, the same for 52 weeks, or no treatment. At the end of treatment the groups looked alike; 18 months after entry, the virus and its e antigen had cleared in 40.6% of the 26-week group and 26.5% of the 52-week group, against 9.4% of untreated controls (Chien 1998). The double-blind US Phase 3, with 97 patients on the same dose or placebo for six months, did not confirm it: complete responses were 14% versus 4%, short of significance (Mutchnick 1999). A Cochrane review published in September 2026 pooled 10 randomized trials with 1,349 participants, rated the evidence low to very low certainty, and concluded that it is unclear whether the drug helps (Naing 2026).

Hepatitis C followed the same arc. Added to interferon in 109 US patients, it more than doubled the share with normal liver enzymes at the end of 26 weeks (37.1% versus 16.2%), but sustained responses were 14.2% versus 8.1% (Sherman 1998). In 552 European patients who had failed earlier treatment, adding it to peginterferon and ribavirin produced sustained cure in 12.7% versus 10.5% on placebo (Ciancio 2012). Both infections are now treated with oral antivirals, and FDA's reviewers found no data showing that adding thymosin alpha-1 to modern care helps (FDA 2024).

Vaccine response in older adults and dialysis patients

The idea has a logic: older adults and people on dialysis respond weakly to flu vaccine. In a double-blind trial in 90 men aged 65 to 99, 900 mcg per square meter of body surface twice a week for four weeks alongside the 1986 flu vaccine caused no toxicity (Gravenstein 1989). By FDA's reading of the full paper, a four-fold antibody rise occurred in 69% of treated men versus 52% on placebo, with the difference concentrated in men 77 and older; a small open-label study in 99 dialysis patients also found higher antibody titers (FDA 2024). None of these studies measured who caught flu, was hospitalized or died, and the older-adult trials predate the high-dose and adjuvanted vaccines now used for people 65 and older.

Sepsis: the trial that answered the question

Ten small trials, 530 patients in all, had pooled to a 41% relative reduction in sepsis deaths, so Chinese intensive-care investigators ran a proper test. TESTS randomized 1,106 adults in 22 units to 1.6 mg every 12 hours for seven days or placebo, double-blind. Deaths by day 28 were 23.4% versus 24.1% (hazard ratio 0.97 after a 2025 correction), deaths by day 90 were 31.0% versus 32.4%, and no secondary or safety outcome differed (Wu 2025). The authors note that the earlier positive trials were small and may have been chance findings. Subgroups hinted at benefit in people 60 and older and harm in those under 60; those are leads for another trial, not results. The study was partly funded by the drug's manufacturer, which makes the null result harder to dismiss.

COVID-19

Early in the pandemic, a retrospective review of 76 severe patients in two Wuhan hospitals reported 11.1% mortality with thymosin alpha-1 versus 30.0% without (Liu 2020), a comparison vulnerable to who was treated and when. A 2023 meta-analysis of nine mostly observational studies with 5,352 patients found no effect on mortality (risk ratio 1.03) and did not support its use in hospitalized adults (Shang 2023). The only double-blind trial, 105 Indian inpatients randomized two to one, reported 3 deaths among 27 treated severe patients versus 5 among 13 on placebo; its first author works for a pharmaceutical company, while the paper declares no conflict (Shetty 2022).

Cancer: melanoma and liver cancer

The largest cancer trial randomized 488 people with metastatic melanoma to five arms combining dacarbazine chemotherapy, interferon and thymosin alpha-1 at 1.6, 3.2 or 6.4 mg. Two thymosin arms had more tumor responses than control, and median survival was 9.4 versus 6.6 months, a difference that was not statistically significant (Maio 2010); modern immunotherapies have since replaced that control regimen. In liver cancer, a randomized Phase 2 of 25 patients given chemoembolization with or without 1.6 mg five times a week for 24 weeks found no significant difference in response or survival (Gish 2009), and FDA judged the positive retrospective studies after surgery too limited to show what the drug contributed (FDA 2024).

What you are promised versus what is documented

US clinic and seller pages describe thymosin alpha-1 as an all-purpose immune booster. FDA's 2024 internet survey found compounded injections and nasal sprays marketed for hepatitis, HIV, chronic fatigue, inflammation, sepsis, COVID-19, Lyme disease, allergies, cancer, asthma, COPD and psoriatic arthritis (FDA 2024).

• Documented in randomized trials: delayed viral clearance in some hepatitis B trials, not confirmed in others; modest antibody gains after flu vaccination in older men; no survival benefit in sepsis.
• Suggested but unproven: lower COVID-19 mortality and longer survival in melanoma and liver cancer, from open-label, retrospective or underpowered studies.
• No clinical evidence at all: Lyme disease and ME/chronic fatigue syndrome, for which FDA found no clinical studies; long COVID, where the published work is laboratory experiments on patients' blood cells; and immune support in healthy adults, which no trial has tested.

'Boosting' is also the wrong mental model. A drug that pushes immune activity is a reason for caution in autoimmune disease and after a transplant, which is what the labels abroad say.

Thymosin alpha-1 versus the realistic alternatives

The honest summary for most readers: if you have one of the diseases thymosin alpha-1 was tested in, there is an approved US treatment with better evidence, and if you do not, there is nothing for it to treat.

Dosage: what was studied versus what is sold

Two points matter. First, almost every chart online copies the hepatitis number, 1.6 mg twice a week, and moves it to a population, healthy adults seeking immune support, in which no one has tested it. Second, the trials used a pharmaceutical product of known strength. FDA noted that the highest concentration used in any trial was 2 mg/mL, while the compounded injection proposed to it was 3 mg/mL, a strength with no data and possibly a higher risk of the peptide clumping into aggregates that provoke antibodies (FDA 2024). Our thymosin alpha-1 dosage guide sets out every studied regimen in one table.

Side effects and who should not use it

In trials, thymosin alpha-1 was well tolerated. FDA's review of studies using 1 to 16 mg under the skin for up to 12 months found the most common reactions were irritation, redness or discomfort at the injection site (FDA 2024). In TESTS, adverse events (66.4% versus 67.6%) and serious adverse events (26.8% versus 29.3%) were no more common than on placebo (Wu 2025). The Indonesian label reports drug-related events in under 1% of more than 2,000 people, with rare redness, transient muscle wasting, joint pain with hand swelling, and rash.

Less common signals FDA flagged include transient liver-enzyme (ALT) flares in 22 of 316 hepatitis B patients in one trial, all of whom recovered; thyroid changes in two patients given it with interferon (Sherman 1998); nipple pain in more than 10% of treated patients in the liver-cancer trial; and a fatal immune hemolytic anemia in one of six stem-cell transplant recipients given it with donor lymphocytes, where the drug's role is unknown.

The larger unknowns belong to what is actually sold in the US. FDA's central concern was immunogenicity: a 28-amino-acid peptide injected under the skin, prepared without a monograph or validated testing, can aggregate or carry impurities that provoke antibodies. FDA also found no published reproductive-toxicity or carcinogenicity studies (FDA 2024).

Do not use thymosin alpha-1, or use it only under a specialist, if you:

• take immunosuppressants after an organ or stem-cell transplant (labels abroad treat this as a contraindication unless benefits clearly outweigh risks);
• have an autoimmune disease (the Italian label says use must be judged case by case);
• are pregnant or breastfeeding (contraindicated on the Italian label);
• have allergies or atopy, or have reacted to it before;
• take other immune-modifying drugs;
• are a child (the Italian label excludes children).

Its anti-doping status, which differs from TB-500's, is covered in thymosin alpha-1 vs TB-500.

Legal status in the United States

The full picture is in our legal tracker. For thymosin alpha-1:

• Never approved. No US product contains it, and its orphan designations are not approvals.
• Not compoundable. A 503A pharmacy may compound from a bulk ingredient only if it has a USP monograph, is a component of an FDA-approved drug, or is on FDA's 503A bulks list (or, while that list is pending, in Category 1 under an interim policy). Thymosin alpha-1 meets none of these (FDA 2024).
• Category 2, withdrawn, then reviewed anyway. FDA placed it in Category 2 in 2023 over immunogenicity, impurity and characterization concerns. The nomination was later withdrawn, which moved it off the Category 2 list (Frier Levitt 2026), but FDA evaluated it on its own initiative and recommended against adding it, finding no adequate evidence of effectiveness for any of the 12 uses it reviewed (FDA 2024).
• Committee vote, December 4, 2024. FDA's Pharmacy Compounding Advisory Committee voted 4 yes and 17 no on the free base and the same on the acetate; several members voting no said there was no compelling evidence of effectiveness and safety (FDA minutes 2024).
• Final rule still pending. In a lawsuit over the Category 2 designations of thymosin alpha-1 and three other peptides, FDA said it expected to publish a final rule by March 14, 2027, and in February 2026 the HHS Secretary said he expected FDA to make about 14 restricted peptides more accessible (Frier Levitt 2026). As of October 2026, no rule or listing change for thymosin alpha-1 has followed.

Vials sold online as 'research' thymosin alpha-1 are unapproved drugs, whatever the label says; the tracker covers FDA's 2026 warning letters on that point.

Cost and how to get it

There is no legal US price because there is no legal US product, and we give no purchase guidance for it. A clinic that prescribes thymosin alpha-1 in 2026 is prescribing an unapproved drug that no US pharmacy may legally compound, from a source no regulator has checked. The lawful routes to an unapproved drug are a clinical trial or FDA's expanded-access program, which needs a treating physician, a willing supplier and FDA's agreement; FDA briefed its committee on those routes at the same December 2024 meeting (FDA minutes 2024). Our cost guide lists the questions to ask any provider, starting with which pharmacy and on what legal basis, and the complete guide to peptide therapy explains what a legitimate evaluation looks like.

Older adults and women

Older adults are the population the immune-aging argument targets, and the trials aimed at them measured antibody responses to flu vaccine in the 1980s; no trial has tested infections, frailty or aging outcomes, and our longevity guide ranks it accordingly. For women there are no sex-specific efficacy data. The Italian label contraindicates it in pregnancy and breastfeeding, and FDA found no published reproductive-toxicity studies.

Bottom line

Thymosin alpha-1 is a real drug with a real history: a thymic peptide approved abroad for hepatitis B and as a vaccine adjuvant, and tested in thousands of patients over four decades. That record is also what shows its limits. The hepatitis benefit was delayed, inconsistent and not confirmed in the US, the vaccine data stop at antibody levels, and the best trial ever run, in sepsis, found nothing. The uses it is sold for in the US have no trials at all, and FDA and its advisers voted against letting pharmacies compound it. If you have a disease it was tested in, the approved treatment is better studied; if you are healthy, there is no evidence it does anything for you.

Frequently asked questions

+−What is TA1 peptide used for?

Outside the US, thymalfasin (thymosin alpha-1) is approved in several countries for chronic hepatitis B, in some for hepatitis C alongside interferon, and in Italy as an adjuvant to flu vaccination in people with weakened immunity. It has also been tested in sepsis, COVID-19, melanoma and liver cancer, with weak or null results. In the US it is marketed for general immune support, Lyme disease, chronic fatigue and long COVID, none of which has a clinical trial behind it. It is not approved here and no pharmacy may legally compound it.

+−What are the benefits of thymosin alpha-1?

The documented ones are narrow. In some hepatitis B trials, more patients cleared the virus in the year after treatment ended, although a US Phase 3 did not confirm it. In older men, it modestly increased antibody responses to flu vaccine. Other claimed benefits are unproven or disproved: the largest trial ever run, in 1,106 adults with sepsis, found no survival benefit, and there are no trials in healthy people seeking immune support.

+−Is thymosin alpha-1 FDA approved?

No. Nothing containing thymosin alpha-1 has ever been approved in the United States. It holds four orphan-drug designations, which are incentives to study a drug in a rare disease, not approvals. The synthetic form, thymalfasin, is sold as Zadaxin in other countries, including Italy, India, Singapore and Hong Kong.

+−Can a compounding pharmacy make thymosin alpha-1?

Not legally, as of October 2026. A 503A pharmacy can compound from a bulk ingredient only if it has a USP monograph, is part of an FDA-approved drug or is on FDA's 503A bulks list, and thymosin alpha-1 meets none of these. FDA reviewed it in 2024 and proposed keeping it off the list, and its advisory committee voted 17 to 4 against on December 4, 2024. FDA has not finalized the decision, but nothing allows compounding in the meantime.

+−What are the side effects of thymosin alpha-1?

In trials, the most common problem was discomfort, redness or irritation at the injection site, and in the large sepsis trial adverse events were no more frequent than on placebo. Less common reports include transient liver-enzyme flares in hepatitis B, thyroid changes when combined with interferon, joint pain with hand swelling, and rash. The unknowns are larger for products sold in the US: FDA's main concern is that poorly characterized injected peptide can trigger antibodies.

+−Who should not take thymosin alpha-1?

Labels abroad say it should not be used in people deliberately immunosuppressed for an organ transplant unless the benefit clearly outweighs the risk, in pregnancy or breastfeeding, in children, or in anyone who has reacted to it before, and that use in autoimmune disease must be judged case by case. Caution also applies to people with allergies and to anyone taking other immune-modifying drugs.

+−Does thymosin alpha-1 help long COVID, Lyme disease or chronic fatigue?

There is no clinical evidence that it does. When FDA reviewed thymosin alpha-1 in 2024 it found no clinical studies in Lyme disease or in ME/chronic fatigue syndrome. For long COVID, the published work we found is a laboratory study of patients' blood cells, not a treatment trial. These uses come from marketing and clinic protocols, not research.

+−How long does thymosin alpha-1 take to work?

In the hepatitis B trials that reported a benefit, responses were not visible at the end of six months of treatment and appeared over the following year: in the Taiwanese trial, viral clearance was similar across groups at the end of therapy and higher in the treated group 18 months after starting. In acute illness such as sepsis, a week of treatment made no difference to survival. There is no timeline for healthy people because no one has studied them.

+−Is thymosin alpha-1 the same as TB-500?

No. Thymosin alpha-1 is a 28-amino-acid immune peptide cut from a protein called prothymosin alpha. TB-500 is a synthetic seven-amino-acid fragment of thymosin beta-4, an unrelated actin-binding protein, sold for healing. They share a name because both were first found in the same calf-thymus extract, and they have different genes, functions, evidence and anti-doping status.

Sources

1. StudyChien RN, Liaw YF, Chen TC, Yeh CT, Sheen IS. Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial. Hepatology 1998;27:1383-7. (1998)
2. StudyMutchnick MG et al. Thymosin alpha1 treatment of chronic hepatitis B: results of a phase III multicentre, randomized, double-blind and placebo-controlled study. J Viral Hepat 1999;6:397-403. (1999)
3. ReviewNaing C et al. Thymosin-alpha1 for people with chronic hepatitis B. Cochrane Database Syst Rev 2026;9:CD014610. (2026)
4. StudySherman KE et al. Combination therapy with thymosin alpha1 and interferon for the treatment of chronic hepatitis C infection: a randomized, placebo-controlled double-blind trial. Hepatology 1998;27:1128-35. (1998)
5. StudyCiancio A et al. Thymosin alpha-1 with peginterferon alfa-2a/ribavirin for chronic hepatitis C not responsive to IFN/ribavirin: an adjuvant role? J Viral Hepat 2012;19 Suppl 1:52-9. (2012)
6. StudyGravenstein S et al. Augmentation of influenza antibody response in elderly men by thymosin alpha one. A double-blind placebo-controlled clinical study. J Am Geriatr Soc 1989;37:1-8. (1989)
7. StudyWu J et al. The efficacy and safety of thymosin alpha1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. BMJ 2025;388:e082583 (corrected May 2025). (2025)
8. StudyLiu Y et al. (2020). Thymosin alpha 1 reduces the mortality of severe coronavirus disease 2019 by restoration of lymphocytopenia and reversion of exhausted T cells. Clin Infect Dis 2020;71:2150-7. (2020)
9. ReviewShang W et al. Thymosin alpha1 use in adult COVID-19 patients: a systematic review and meta-analysis on clinical outcomes. Int Immunopharmacol 2023;114:109584. (2023)
10. StudyShetty A et al. A double-blind multicenter two-arm randomized placebo-controlled phase-III clinical study to evaluate the effectiveness and safety of thymosin alpha1 as an add-on treatment to existing standard of care treatment in moderate-to-severe COVID-19 patients. Indian J Crit Care Med 2022;26:913-9. (2022)
11. StudyMaio M et al. Large randomized study of thymosin alpha 1, interferon alfa, or both in combination with dacarbazine in patients with metastatic melanoma. J Clin Oncol 2010;28:1780-7. (2010)
12. StudyGish RG, Gordon SC, Nelson D, Rustgi V, Rios I. A randomized controlled trial of thymalfasin plus transarterial chemoembolization for unresectable hepatocellular carcinoma. Hepatol Int 2009;3:480-9. (2009)
13. RegulatoryFDA. Evaluation of thymosin alpha-1 (Ta1)-related bulk drug substances (Ta1 free base and Ta1 acetate) for inclusion on the 503A bulk drug substances list. Briefing document, Pharmacy Compounding Advisory Committee meeting of December 4, 2024. (2024)
14. RegulatoryFDA. Final summary minutes of the Pharmacy Compounding Advisory Committee meeting of December 4, 2024 (AOD-9604, CJC-1295 and thymosin alpha-1), approved February 21, 2025. (2025)
15. NewsFerrari Faviero G, Asebey EJ. The peptide landscape is shifting: what Secretary Kennedy's Joe Rogan interview could mean for the compounding industry. Frier Levitt, March 10, 2026. (2026)