Ac-SDKP (TB-500 Fragment 1-4)_Dosage, benefits & legal status
Also known as Ac-SDKP, goralatide, seraspenide, thymosin beta-4 (1-4), TB4 fragment 1-4
The first four amino acids of TB-500, and a drug candidate in its own right.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Ac-SDKP (TB-500 Fragment 1-4)?
Plain language first. The technical label stays, but it never stands alone.Overview
It is the first four residues of TB-500, and the body already makes it on its own.
Ac-SDKP is N-acetyl-Ser-Asp-Lys-Pro, an endogenous tetrapeptide cut from thymosin beta-4 by meprin-alpha and prolyl oligopeptidase, with antifibrotic and anti-inflammatory activity in animal models.
What it's used for
A short piece of TB-500, sold for inflammation and scarring. It was once a drug candidate for chemotherapy patients.
How does Ac-SDKP (TB-500 Fragment 1-4) work?
What it does in the body, and where.Ac-SDKP is not really a drug the body has never seen. It is a signal the body makes and then immediately destroys.
- 01Two enzymes cut it off the front of thymosin beta-4Meprin-alpha and prolyl oligopeptidase, working together. Neither does it alone.
- 02It blocks Smad2 phosphorylationThat dials down the genes TGF-beta switches on, and TGF-beta is the main driver of scarring.
- 03ACE destroys it almost immediatelyThe N-terminal domain of angiotensin-converting enzyme is its near-exclusive route of breakdown. Researchers describe the resulting half-life as extremely short and a real obstacle to using it.
- 04This is why ACE inhibitors are part of the storyBlocking ACE raises your own Ac-SDKP several-fold, and some of the antifibrotic benefit of ACE inhibitors is attributed to exactly that.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
- Reducing fibrosis in heart, kidney, lung and liverEarly research
- Protecting bone marrow stem cells during chemotherapy, as goralatideInvestigational
- Anti-inflammatory and tissue remodelling effectsEarly research
- General recovery and healing, as soldResearch only
The published record
Papers and trials about Ac-SDKP (TB-500 Fragment 1-4)
89 papers tagged human · 41 not reviews or lab · 4 clinical trial publications
1 registered trials · none with posted results
Furthest stage reached: Phase 1, completed, no results posted
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Ac-SDKP (TB-500 Fragment 1-4)
How much, and do you cycle it?
The range, and whether you take breaks.No established human dose, no established schedule. No established schedule No range
No human study has established a duration or a break for the use this is sold for. Animal protocols dosed twice weekly for a few weeks, which is a study design rather than a recommendation.
How long does it stay in the body?
The half-life, and where the figure comes from.Minutespeer-reviewed
Described in the literature as extremely short in vivo, which is the stated reason d-amino acid analogs were developed. The specific figure differs between rat and human serum and we have not pinned one down, so none is shown.
Not yet traced to a primary source.
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
Ac-SDKP (TB-500 Fragment 1-4) starts at $169.00 across 1 vendor.
2 listings, last read Oct 10, 2026. Shipping and card fees are not included.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Ac-SDKP (TB-500 Fragment 1-4) keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Active cancer, since it promotes new blood vessel growth and thymosin beta-4 levels track with poor outcomes in some tumors
- Pregnancy
- Taking an ACE inhibitor, where endogenous levels are already raised several-fold
- Banned in drug-tested sport
Stop and get help
- New lumps or masses
- Spreading redness, heat or swelling at an injection site
- Unusual bruising or bleeding
- Signs of an allergic reaction such as face or throat swelling, hives, or trouble breathing
Common effects
- Injection site reactions
- Almost all evidence is from animals, so the human profile is not established
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Ac-SDKP (TB-500 Fragment 1-4) approved?
And where the numbers on this page come from.No. Ac-SDKP (TB-500 Fragment 1-4) is not approved for any use, anywhere. It is sold labeled for laboratory research only, and there is no legal route to buy it for human use.
- Approval statusResearch only
- RouteUnder the skin, or by mouth
- Checked24 August 2026
- DoseFrom community reports. No regulator or trial established this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
Not approved anywhere. The name it was developed under is goralatide, also called seraspenide, and it went into clinical work as a chemoprotectant, meant to hold bone marrow stem cells in a resting state so chemotherapy would spare them. That program did not produce an approved product. The antifibrotic work that vendor pages describe is animal research in heart, kidney, lung and liver, and none of it is human efficacy data. Banned in drug-tested sport as part of the thymosin beta-4 class.
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
What else is like Ac-SDKP (TB-500 Fragment 1-4)?
Others in Healing and recovery, side by side.If you're weighing Ac-SDKP (TB-500 Fragment 1-4), it's worth reading Larazotide, Teriparatide (Forteo), and Abaloparatide (Tymlos) in the same class.
The first four amino acids of TB-500, and a drug candidate in its own right.
- Dose
- No established human dose
- How often
- No established schedule
An oral peptide studied for sealing a leaky gut, mainly in celiac disease.
- Dose
- 0.5 mg per dose
- How often
- Before meals
The bone drug that builds new bone instead of just slowing the loss.
- Dose
- 20 mcg per day
- How often
- Daily
A bone-building drug that completes the family around teriparatide.
- Dose
- Set by the label
- How often
- Once daily
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- Kanasaki et al., release of Ac-SDKP from thymosin beta-4, American Journal of Physiology Renal Physiology(2016)Ac-SDKP is released from thymosin beta-4 only by meprin-alpha and prolyl oligopeptidase acting together.
- Bleomycin pulmonary fibrosis model with Ac-SDKP(2016)Endogenous tetrapeptide generated from thymosin beta-4 and a natural substrate of the ACE N-domain; antifibrotic activity in mice.
Beyond these, 186 records are indexed. Browse the records