TB-4 FRAG / Ac-SDKP Protocol Guide
TB-4 FRAG, also known as Ac-SDKP (N-acetyl-seryl-aspartyl-lysyl-proline), is the bioactive anti-fibrotic tetrapeptide fragment derived from the N-terminal region of Thymosin Beta-4. This endogenous peptide is naturally produced by enzymatic cleavage and degraded by ACE (angiotensin-converting enzyme). Ac-SDKP potently inhibits collagen synthesis, reduces cardiac and organ fibrosis, promotes angiogenesis, protects cardiomyocytes from ischemic damage, and modulates inflammatory macrophage polarization. This protocol covers subcutaneous dosing at 200-750mcg daily, cycling strategies, cardiac biomarker monitoring, and stacking for comprehensive tissue repair research.
Protocol Overview
- Compound
- Ac-SDKP (TB-4 FRAG / N-acetyl-Ser-Asp-Lys-Pro)
- Category
- Cardiac Repair / Anti-Fibrotic
- Mechanism
- Inhibits collagen I/III synthesis, reduces TGF-beta/Smad signaling, promotes angiogenesis, anti-inflammatory macrophage polarization (M1 to M2 shift)
- Molecular Weight
- 487.51 g/mol
- Half-Life
- ~4.5 minutes (rapidly degraded by ACE)
- Form
- Lyophilized powder (5mg vials)
- Route
- Subcutaneous
- Frequency
- 1-2x daily
- Cycle Length
- 4-8 weeks on, 2-4 weeks off
Dosing Protocol
| Protocol | Dose | Frequency | Route | Duration |
|---|---|---|---|---|
| Introductory | 200 mcg | 1x daily | SubQ | 1 week |
| Standard | 500 mcg | 1x daily | SubQ | 4-8 weeks |
| Advanced | 750 mcg | 1x daily | SubQ | 4-8 weeks |
| Split Dose | 250 mcg | 2x daily (AM + PM) | SubQ | 4-8 weeks |
Key principle: Due to the very short half-life (~4.5 min), Ac-SDKP acts through signaling cascades rather than sustained receptor occupancy. Consistent daily dosing maintains anti-fibrotic gene expression changes. Split dosing may improve sustained effects.
Reconstitution Guide
Standard Reconstitution
- Vial: 5mg Ac-SDKP lyophilized powder
- Diluent: 2mL bacteriostatic water
- Concentration: 2.5mg/mL (2,500mcg/mL)
- 500mcg dose: 20 units on insulin syringe
- Vial yield: 10 doses at 500mcg
Storage & Handling
- Pre-reconstitution: Store at -20°C or refrigerated
- Post-reconstitution: Refrigerate at 2-8°C
- Stability: Use within 21 days once reconstituted
- Note: ACE inhibitor co-administration raises endogenous Ac-SDKP levels
Expected Timeline
Side Effects & Monitoring
Common Side Effects
- Injection site redness (mild, transient)
- Mild hypotension (rare, due to ACE pathway interaction)
- Headache (uncommon)
Ac-SDKP is a naturally occurring endogenous peptide and is generally well-tolerated. Serious adverse effects have not been reported in preclinical research.
Precautions
- Interaction with ACE inhibitors (raises endogenous Ac-SDKP 5x)
- Monitor blood pressure if combining with antihypertensives
- Limited human clinical data available
- Avoid in active bleeding or immediately post-surgery
- Not recommended during pregnancy
Stacking Recommendations
Compatible Compounds
- TB-500: Full-length thymosin beta-4 for broader tissue repair
- BPC-157: Complementary healing and anti-inflammatory pathways
- GHK-Cu: Tissue remodeling and anti-fibrotic synergy
- Thymosin Alpha-1: Immune modulation for systemic repair
- CoQ10: Mitochondrial support for cardiac tissue
Popular Stacks
- Cardiac Repair: Ac-SDKP 500mcg + TB-500 2mg 2x/wk
- Anti-Fibrotic: Ac-SDKP 500mcg + BPC-157 250mcg daily
- Tissue Remodel: Ac-SDKP 500mcg + GHK-Cu 200mcg daily
Blood Work Recommendations
| Panel | Markers | Timing |
|---|---|---|
| Cardiac Markers | BNP/NT-proBNP, troponin, CK-MB | Baseline, Week 4, Week 8 |
| Fibrosis Markers | Galectin-3, sST2, PICP, PIIINP | Baseline, Week 4, Week 8 |
| Inflammation | hs-CRP, IL-6, TNF-alpha | Baseline, Week 4, Week 8 |
| Renal Function | Creatinine, BUN, eGFR | Baseline, Week 8 |
Cardiac biomarkers (BNP, troponin) and fibrosis markers (galectin-3, sST2) provide the most relevant data for evaluating anti-fibrotic efficacy. Echocardiography is recommended at baseline and post-protocol.
Related Tools & Resources
