Peptide

TB-4 Fragment variants (non-TB-500 marketing)

Also known as

TB4 frag · TB-4 Frag · TB4-FRAG · TB-4 FRAG · thymosin fragments · Ac-SDKP · N-acetyl-Ser-Asp-Lys-Pro · N-acetyl-seryl-aspartyl-lysyl-proline · TB4 Frag 1-4 · Thymosin Beta-4 Fragment (1-4) · Tβ4 N-terminal fragment · Goralatide · thymosin beta-4 fragments (non-TB-500) · AcSDKP

Community talk. May contain inaccuracies. Not medical advice. Not a protocol. Not for human or animal use.

What it is

Fragment identity	Ac-SDKP, or goralatide, is thymosin beta-4's four-amino-acid 1–4 fragment. Full Tβ4 has 43 amino acids; the identified TB-500 fragment is Ac-LKKTETQ, positions 17–23.
Forms differ	Ac-SDKP appears in SubQ charts and oral blends. TB4 frag labeling alone does not verify the fragment, and calling a capsule oral TB-500 blurs identity and absorption.

Notes

Ac-SDKP is the 1–4 fragment, also called goralatide. Its sequence is acetyl-Ser-Asp-Lys-Pro. The full parent has 43 amino acids; the analytically identified TB-500 fragment is Ac-LKKTETQ, positions 17–23. Different pieces can have different biological roles. “TB4 frag” alone does not establish which one a product contains. Kumar et al. — Ac-SDKP release from thymosin-β4 (Animal context · Accessed 2026-09-30) · WADA research project 13D34PV — TB-500 metabolism (Official context · Accessed 2026-09-30)

Capsules and injections are different discussions. Ac-SDKP appears in SubQ (under-the-skin injection) charts and oral capsule blends. Calling a capsule “oral TB-500” blurs identity and absorption. Forum opinions disagree; a smaller fragment or enteric coating does not by itself demonstrate equivalent effects. Oral TB-4 FRAG + BPC-157 ARG (Community discussion · Accessed 2026-09-30)

Source context — Kumar et al. — Ac-SDKP release from thymosin-β4: Animal and in-vitro mechanism with cited organ models, not a human injury trial. No animal amount placed in the five practical subjects.

Source context — WADA research project 13D34PV — TB-500 metabolism: Identity of the analyzed TB-500 product; not certification of all marketed vials or proof of human benefit. Project approved 2013; page date unspecified.

Source context — Oral TB-4 FRAG + BPC-157 ARG: Unverified combination and commenter label interpretation, no assay or controlled comparison. Replies asserting oral activity or TB-500 equivalence are opinions. Only relative dates displayed; no publication date inferred.

What people notice

Movement and stiffness	Oral blend users report easier tendon movement or near-full movement during a short course; another saw no change after two weeks. BPC-157 and recovery measures prevent isolating Ac-SDKP.
Benefit with a difficult aftermath	One month-long oral-blend user described shoulder, flexibility, strength and focus improvements, followed after stopping by exhaustion that impaired work and exercise.
Scarring and fibrosis hopes	Animal and cell research motivates interest in less organ scarring; it does not establish that retail capsules reverse human fibrosis.

Notes

Easier movement and less persistent irritation. Recovery users seek less stiffness, improved tendon movement and a return to activity. Those are felt outcomes; they do not show that tissue has repaired, especially when BPC-157, rehabilitation and rest are involved.

Improvement and nonresponse coexist. The oral thread includes near-full movement after a course shorter than a month and no change after two weeks. Replies disagree over absorption; neither opinion settles it. Oral TB-4 FRAG + BPC-157 ARG (Community discussion · Accessed 2026-09-30)

The promising month and the difficult aftermath belong together. The adverse author took a 700 mcg oral blend each morning for a month and described shoulder improvement over three weeks, better flexibility, strength and focus, followed by exhaustion that impaired work and exercise. The unverified blend's component ratio was not supplied. TB-4 Frag+BPC-157 ARG - Side Effects/ Fatigue/Depressed/Aches (Personal report · Accessed 2026-09-30)

Less scarring is the separate anti-fibrotic appeal. Fibrosis means excess scar-like tissue in an organ. The older discussion links Ac-SDKP to heart, kidney and lung remodeling. Animal and cell research explains that interest, but does not establish that retail capsules reverse human fibrosis.

Source context — TB-4 Frag+BPC-157 ARG - Side Effects/ Fatigue/Depressed/Aches: Unverified combination product and causality; other illness and recovery factors unresolved. No clinical diagnosis supplied. Unrelated self-treatment details are omitted. Relative publication date only.

Doses people talk about

SubQ chart amounts	200, 500 and 750 mcg once daily appear as separate chart entries; 250 mcg twice daily totals 500 mcg/day. These are not validated dose tiers or a safe escalation ladder.
Competing guides	A separate preclinical-derived band gives 0.5–2 mg/day SubQ. Another guide gives 100, 300 and 500 mcg entries but has inconsistent fragment identities.
Oral capsules and blends	Older marketing lists 500 mcg capsules once daily. A commenter describes a 700 mcg blend as 500 mcg TB component plus 200 mcg BPC per capsule; a two-capsule schedule implies 1,000 and 400 mcg/day respectively, without verified contents.
Mixed-fragment oral guide	One commercial guide lists 250 mcg–1 mg/day while grouping Ac-SDKP and Ac-LKKTETQ without a component ratio. It does not establish absorption or an Ac-SDKP-only amount.

Notes

SubQ charts: 200, 500 or 750 mcg once daily. The original protocol-blog record describes 200 mcg as an introductory amount, 500 mcg as a recurring chart target and 750 mcg as an upper step. These are reported chart entries, not validated doses or a safe escalation ladder. mcg means micrograms; 1 mg is 1,000 mcg.

Split SubQ example: 250 mcg twice daily, 500 mcg/day. Other preserved guides give 0.5–2 mg/day SubQ as a research-reference band extrapolated from preclinical work. That higher range is a different claim with a different origin, not additional evidence for a human community standard.

A competing guide lists 100, 300 and 500 mcg. Peptok lists 100 mcg daily/every other day, 300 mcg daily and 500 mcg daily split. Its inconsistent fragment identities weaken the chart's credibility; it documents circulating claims. Peptok — Thymosin Beta-4 Fragment guide (Secondhand community claim · Accessed 2026-09-30)

Oral labels: 500 mcg capsules and a 700 mcg blend. The older record describes 500 mcg once-daily capsule marketing. A Reddit commenter assigns 500 mcg to the TB component and 200 mcg to BPC-157 per capsule; another repeats two capsules/day. That implies 1,000 and 400 mcg/day respectively, but neither identity nor contents were verified. Oral TB-4 FRAG + BPC-157 ARG (Community discussion · Accessed 2026-09-30)

Commercial oral guide: 250 mcg–1 mg/day. LVLUP's 2024 guide groups Ac-SDKP and Ac-LKKTETQ in delayed-release capsules without specifying the component ratio. It claims oral activity; the guide alone does not establish absorption. LVLUP Health — Peptide Quick Reference Guide (2024) (Community guide · Accessed 2026-09-30)

Source context — Peptok — Thymosin Beta-4 Fragment guide: Commercial features include vendor directory/calculators/paid guide; unclear chart origin. Header gives Ac-SDKP but body says 17–23, calls TB-500 both Ac-LKKTETQ and 43 amino acids, and gives an inconsistent mass. Supports only what its chart repeats, not identity, efficacy or safety.

Source context — LVLUP Health — Peptide Quick Reference Guide (2024): Commercial guide, accessed as a forum-hosted copy. Groups two fragments; no component ratio or demonstrated human absorption. Copyright 2024, exact publication date unknown.

Half-life, onset & duration

Felt onset	One oral-blend user reported easier tendon movement after 3–4 days. Blog remodeling checkpoints are not measured onset of fibrosis reversal.
Felt duration	No dependable single-dose benefit window is established. One blend account describes unwanted symptoms through weeks 5–6 after stopping, without proving withdrawal or retained peptide.
Half-life	4.5 minutes was measured after a 12-hour IV Ac-SDKP infusion ended in six healthy volunteers. The abstract gives no separate SubQ/IM terminal half-life or oral result.
Research blood peak	Separate SubQ and IM research injections peaked at 0.26 and 0.28 hours respectively. Blood peak is not felt onset or proof of retail-product equivalence.

Notes

Days in positive blend reports; no change at two weeks in another. One capsule user reported easier tendon movement after 3–4 days. Older protocol blogs describe 3–4-week reassessment and 5–8-week remodeling claims; those are proposed checkpoints, not measured onset of fibrosis reversal. Oral TB-4 FRAG + BPC-157 ARG (Community discussion · Accessed 2026-09-30)

No dependable single-dose benefit window. The original discussion describes comfort persisting or fading as activity returns. Reports mostly cover repeated use. Tissue-remodeling lore cannot show how long one dose acts, and short blood clearance does not define how long symptoms last.

Post-stop symptoms can last beyond a course. The adverse blend author described symptoms through weeks 5–6 after stopping. This chronology does not prove withdrawal, ongoing peptide in blood or Ac-SDKP causation. TB-4 Frag+BPC-157 ARG - Side Effects/ Fatigue/Depressed/Aches (Personal report · Accessed 2026-09-30)

4.5 minutes was measured after an IV infusion ended. In six healthy volunteers given 128 nmol/kg, the 1994 study reported this mean elimination half-life after a 12-hour infusion. Separate SubQ/IM injections peaked at 0.26/0.28 hours with 100%/81% bioavailability; the abstract supplies no separate injection terminal half-life or oral result. A blood peak is not felt onset. Ezan et al. — NAc-SDKP pharmacokinetics (1994) (Official context · Accessed 2026-09-30)

Source context — Ezan et al. — NAc-SDKP pharmacokinetics (1994): Abstract only, small old pharmaceutical study; no separate SC/IM terminal half-life, retail equivalence or oral result. Five chemotherapy patients were a separate infusion cohort.

Cycles people discuss

Chart conventions	4–8 weeks on and 2–4 weeks off appear in older charts, with 1–2-week introductory probes. Injury notes discuss stopping when symptoms settle or at a 4–6-week no-change checkpoint.
Longer blocks	Organ/fibrosis discussion includes longer or repeated blocks; oral marketing follows bottle-length courses. Neither establishes long-term safety or a required reset.

Notes

Older charts: 4–8 weeks on, 2–4 weeks off. They also describe a 1–2-week introductory probe, sometimes one week at 200 mcg before a higher chart amount. Injury discussions mention stopping when symptoms settle or after a 4–6-week no-change checkpoint. These are conventions, not established required cycles.

Courses differ from remodeling claims. Longer organ/fibrosis blocks and later reruns appear in the older record, while oral marketing follows bottle-length courses. Neither a bottle nor a planned break establishes long-term safety or a biological reset.

Stacks

Separate repair examples	Blog examples pair Ac-SDKP 500 mcg/day with TB-500 2 mg twice weekly, BPC-157 250 mcg/day, or GHK-Cu 200 mcg/day. These are separate combinations, not one combined recipe.
GLOW and KLOW	Ac-SDKP is sometimes added separately to these stacks; it is not a standardized ingredient. The older 5:1:1 ratio lacks component order, so no amounts can be assigned.
Other combinations	Full-length Tβ4, Thymosin Alpha-1, CoQ10 and GH-axis agents also appear, alongside rest and rehabilitation.

Notes

Stack claims try to cover different parts of repair. Preserved blog examples pair Ac-SDKP 500 mcg/day with TB-500 2 mg twice weekly, BPC-157 250 mcg/day, or GHK-Cu 200 mcg/day. These are separate examples. Ac-SDKP is sometimes added separately to GLOW stack or KLOW stack. The older GLOW notes mention 5:1:1 ratio talk without component order; no amounts can be inferred.

GLOW context: GLOW is commonly BPC + TB-500 + GHK-Cu (vendor ratios vary, e.g. 5:1:1 style talk) — Ac-SDKP is sometimes added as a fourth “anti-fibrotic” vial rather than being inside the named blend. [community]

KLOW context: KLOW typically extends GLOW with KPV; Ac-SDKP is again an optional separate frag, not a standardized KLOW ingredient. [community]

Convenience does not answer the identity question. The bodybuilding forum's oral-product question leads into injected TB-500/BPC experiences. Those reports concern different formulations. The older record also mentions full-length Tβ4, Thymosin Alpha-1, CoQ10 and GH-axis combinations; more compounds make credit harder to assign. Oral BPC 157 Arginate salt, and oral TB 500 (AC-SDKP) (Community discussion · Accessed 2026-09-30)

Non-peptide foundations: Load management, PT, sleep, and nutrition still get credit when subjective outcomes look good. [community]

Source context — Oral BPC 157 Arginate salt, and oral TB 500 (AC-SDKP): Hybrid and repeat requests returned 403. Not an Ac-SDKP-only effectiveness log; injected-blend numbers are not adopted here. Vendor endorsements are not quality evidence.

Watch for

Serious post-course symptoms	One oral-blend author reported fatigue, low mood, anxiety, aches, dizziness and shortness of breath beginning 1–2 weeks after stopping. Cause was unverified; breathlessness or severe decline needs medical assessment.
Other complaints	Injection irritation, headache, fatigue, nausea and rare blood-pressure-drop narratives occur in mixed-peptide notes, without Ac-SDKP-specific rates.
Medicines and product uncertainty	ACE inhibitors raise endogenous Ac-SDKP; that is not a strategy for extending a research product. Exogenous combinations, pregnancy, growth-pathway effects and unverified contents remain uncertain.
Sport context	The saved WADA entry covers thymosin beta-4 and derivatives. Ac-SDKP's absence as an individual name is not clearance.

Notes

Early benefit can be followed by substantial problems. An oral-blend author reported fatigue, low mood, anxiety, aches, dizziness and shortness of breath beginning 1–2 weeks after stopping. The cause was unverified. Breathlessness or severe functional decline warrants medical assessment, not being dismissed as a necessary recovery phase. TB-4 Frag+BPC-157 ARG - Side Effects/ Fatigue/Depressed/Aches (Personal report · Accessed 2026-09-30)

Routine complaints are poorly attributable. The older record includes injection-site redness, itching or swelling, headache, fatigue, nausea and rare blood-pressure-drop narratives. These often involve several peptides; frequencies and Ac-SDKP-specific risk are unknown.

ACE inhibitors change the biological background. A small human captopril study raised naturally occurring Ac-SDKP about 5.5-fold. That is a reason medication context matters, not a strategy for extending a research product's action. It does not establish the safety of adding exogenous Ac-SDKP. Azizi et al. — ACE inhibition increases plasma Ac-SDKP (1996) (Official context · Accessed 2026-09-30)

Product and growth-pathway uncertainties matter. Label identity, amount, contamination and sterility remain concerns; a certificate alone cannot verify the actual vial. The older guides flag pregnancy/breastfeeding, malignancy or chemotherapy, and immediate surgical/bleeding contexts. Repair and blood-vessel-growth signaling underlies the theoretical cancer concern; fragment-specific human risk is not quantified.

A fragment name is no sports exemption. The saved WADA entry prohibits thymosin beta-4 and its derivatives, naming TB-500 as an example. Ac-SDKP is not separately named in that entry; absence of its name is not clearance. WADA — The Prohibited List (Official context · Accessed 2026-09-30)

Source context — Azizi et al. — ACE inhibition increases plasma Ac-SDKP (1996): Small endogenous-peptide study; does not test coadministration of exogenous Ac-SDKP. JCI HTML timed out and content-assets PDF failed; this publisher-distribution PDF opened.

Source context — WADA — The Prohibited List: Dynamic current list accessed on date stated. Entry does not individually name Ac-SDKP or provide a fragment-specific ruling; not a clearance opinion.

Full notes

TB-4 fragments are short pieces of thymosin beta-4. Ac-SDKP is the four-amino-acid fragment discussed for scarring, inflammation and recovery. Oral blend reports include easier movement, no improvement and serious unwanted symptoms; they cannot isolate the fragment.

What the fragment actually is

Ac-SDKP is the 1–4 fragment, also called goralatide. Its sequence is acetyl-Ser-Asp-Lys-Pro. The full parent has 43 amino acids; the analytically identified TB-500 fragment is Ac-LKKTETQ, positions 17–23. Different pieces can have different biological roles. “TB4 frag” alone does not establish which one a product contains. Animal context Official context
Capsules and injections are different discussions. Ac-SDKP appears in SubQ (under-the-skin injection) charts and oral capsule blends. Calling a capsule “oral TB-500” blurs identity and absorption. Forum opinions disagree; a smaller fragment or enteric coating does not by itself demonstrate equivalent effects. Reddit · r/Peptides Community

Why people look it up

Easier movement and less persistent irritation. Recovery users seek less stiffness, improved tendon movement and a return to activity. Those are felt outcomes; they do not show that tissue has repaired, especially when BPC-157, rehabilitation and rest are involved. Community
Less scarring is the separate anti-fibrotic appeal. Fibrosis means excess scar-like tissue in an organ. The older discussion links Ac-SDKP to heart, kidney and lung remodeling. Animal and cell research explains that interest, but does not establish that retail capsules reverse human fibrosis. Community

Doses people discuss

Amounts describe discussion, not instructions. Oral blend totals, component amounts and injection charts must stay separate.

SubQ charts: 200, 500 or 750 mcg once daily. The original protocol-blog record describes 200 mcg as an introductory amount, 500 mcg as a recurring chart target and 750 mcg as an upper step. These are reported chart entries, not validated doses or a safe escalation ladder. mcg means micrograms; 1 mg is 1,000 mcg. Community
Split SubQ example: 250 mcg twice daily, 500 mcg/day. Other preserved guides give 0.5–2 mg/day SubQ as a research-reference band extrapolated from preclinical work. That higher range is a different claim with a different origin, not additional evidence for a human community standard. Community
A competing guide lists 100, 300 and 500 mcg. Peptok lists 100 mcg daily/every other day, 300 mcg daily and 500 mcg daily split. Its inconsistent fragment identities weaken the chart's credibility; it documents circulating claims. Peptok peptide guide
Oral labels: 500 mcg capsules and a 700 mcg blend. The older record describes 500 mcg once-daily capsule marketing. A Reddit commenter assigns 500 mcg to the TB component and 200 mcg to BPC-157 per capsule; another repeats two capsules/day. That implies 1,000 and 400 mcg/day respectively, but neither identity nor contents were verified. Community Reddit · r/Peptides
Commercial oral guide: 250 mcg–1 mg/day. LVLUP's 2024 guide groups Ac-SDKP and Ac-LKKTETQ in delayed-release capsules without specifying the component ratio. It claims oral activity; the guide alone does not establish absorption. Community guide

Half-life

About 4–5 minutes is repeated in guides. This comes from formal Ac-SDKP pharmacokinetics, not a forum measurement of retail capsules. Daily or split-daily schedules are justified with this number in the older discussion; the precise study route is explained below. Community Peptok peptide guide

Onset: when people notice a change

Days in positive blend reports; no change at two weeks in another. One capsule user reported easier tendon movement after 3–4 days. Older protocol blogs describe 3–4-week reassessment and 5–8-week remodeling claims; those are proposed checkpoints, not measured onset of fibrosis reversal. Reddit · r/Peptides Community

Duration: how long a change lasts

No dependable single-dose benefit window. The original discussion describes comfort persisting or fading as activity returns. Reports mostly cover repeated use. Tissue-remodeling lore cannot show how long one dose acts, and short blood clearance does not define how long symptoms last. Community
Post-stop symptoms can last beyond a course. The adverse blend author described symptoms through weeks 5–6 after stopping. This chronology does not prove withdrawal, ongoing peptide in blood or Ac-SDKP causation. Personal report

Cycles and breaks

Older charts: 4–8 weeks on, 2–4 weeks off. They also describe a 1–2-week introductory probe, sometimes one week at 200 mcg before a higher chart amount. Injury discussions mention stopping when symptoms settle or after a 4–6-week no-change checkpoint. These are conventions, not established required cycles. Community
Courses differ from remodeling claims. Longer organ/fibrosis blocks and later reruns appear in the older record, while oral marketing follows bottle-length courses. Neither a bottle nor a planned break establishes long-term safety or a biological reset. Community

Good to know before interpreting a report

Early benefit can be followed by substantial problems. An oral-blend author reported fatigue, low mood, anxiety, aches, dizziness and shortness of breath beginning 1–2 weeks after stopping. The cause was unverified. Breathlessness or severe functional decline warrants medical assessment, not being dismissed as a necessary recovery phase. Personal report
Routine complaints are poorly attributable. The older record includes injection-site redness, itching or swelling, headache, fatigue, nausea and rare blood-pressure-drop narratives. These often involve several peptides; frequencies and Ac-SDKP-specific risk are unknown. Community
ACE inhibitors change the biological background. A small human captopril study raised naturally occurring Ac-SDKP about 5.5-fold. That is a reason medication context matters, not a strategy for extending a research product's action. It does not establish the safety of adding exogenous Ac-SDKP. Official context
Product and growth-pathway uncertainties matter. Label identity, amount, contamination and sterility remain concerns; a certificate alone cannot verify the actual vial. The older guides flag pregnancy/breastfeeding, malignancy or chemotherapy, and immediate surgical/bleeding contexts. Repair and blood-vessel-growth signaling underlies the theoretical cancer concern; fragment-specific human risk is not quantified. Community
A fragment name is no sports exemption. The saved WADA entry prohibits thymosin beta-4 and its derivatives, naming TB-500 as an example. Ac-SDKP is not separately named in that entry; absence of its name is not clearance. Official context

What people report and argue about

Improvement and nonresponse coexist. The oral thread includes near-full movement after a course shorter than a month and no change after two weeks. Replies disagree over absorption; neither opinion settles it. Reddit · r/Peptides
The promising month and the difficult aftermath belong together. The adverse author took a 700 mcg oral blend each morning for a month and described shoulder improvement over three weeks, better flexibility, strength and focus, followed by exhaustion that impaired work and exercise. The unverified blend's component ratio was not supplied. Personal report
Stack claims try to cover different parts of repair. Preserved blog examples pair Ac-SDKP 500 mcg/day with TB-500 2 mg twice weekly, BPC-157 250 mcg/day, or GHK-Cu 200 mcg/day. These are separate examples. Ac-SDKP is sometimes added separately to GLOW stack or KLOW stack. The older GLOW notes mention 5:1:1 ratio talk without component order; no amounts can be inferred. Community
Convenience does not answer the identity question. The bodybuilding forum's oral-product question leads into injected TB-500/BPC experiences. Those reports concern different formulations. The older record also mentions full-length Tβ4, Thymosin Alpha-1, CoQ10 and GH-axis combinations; more compounds make credit harder to assign. Steroid.com forum Community

Supporting research: what the numbers actually mean

The body releases Ac-SDKP from a larger peptide. Animal and laboratory work identified sequential cleavage by meprin-α and prolyl oligopeptidase. That pathway links the fragment to thymosin beta-4, but does not make the two interchangeable. Animal context
4.5 minutes was measured after an IV infusion ended. In six healthy volunteers given 128 nmol/kg, the 1994 study reported this mean elimination half-life after a 12-hour infusion. Separate SubQ/IM injections peaked at 0.26/0.28 hours with 100%/81% bioavailability; the abstract supplies no separate injection terminal half-life or oral result. A blood peak is not felt onset. Official context
Organ-remodeling biology is supporting context. The inspected animal/laboratory paper discusses reduced inflammation and collagen deposition in heart, kidney, lung and liver models. Goralatide's marrow-protection history concerns regulation of cell proliferation, not a proven sports-injury benefit. Preclinical infusion exposure does not validate retail once-daily charts. Animal context Community