Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of PEG-MGF and TB-500 — mechanism, dosing, side effects, legal status, and pricing.
PEG-MGF is the pegylated form of Mechano Growth Factor (MGF), the distinct 24-amino-acid C-terminal E-peptide encoded by the IGF-1Ec splice variant (IGF-1Eb in rodents) that is transiently upregulated in muscle after mechanical loading or damage. MGF is related to but pharmacologically distinct from mature IGF-1 and IGF-1 LR3. Pegylation extends its half-life from minutes to several hours, and the compound is marketed as a research chemical for muscle repair protocols. It is not FDA-approved for any indication.
TB-500 is a synthetic N-acetylated heptapeptide (Ac-LKKTETQ) corresponding to amino acids 17–23 of thymosin β4, the actin-binding region of the native 43-residue protein. Despite widespread vendor labeling, TB-500 is NOT identical to full-length thymosin β4 (Tβ4); it is a short fragment containing the central actin-binding motif. It is sold as a research chemical and is not FDA-approved for any human indication.
PEG-MGF
TB-500
Category
Legal Status
Mechanism
Dose Range
Route
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
PEG-MGF
TB-500
COA corpus from Disclosed Labs — independently tested batches only.
PEG-MGF
12
COAs
99.6%
Avg purity
5
Labs
TB-500
170
COAs
99.3%
Avg purity
16
Labs
TB-500 is among peptides under FDA review for the Category 1 (503A) list; if added, it would require a prescription to be compounded by registered 503A/503B pharmacies — not yet authorized. PEG-MGF remains research-only. In April 2026 the FDA removed 12 peptides from Category 2, which does not place them on the Category 1 list or authorize compounding. The FDA's Pharmacy Compounding Advisory Committee is advisory and meets July 23–24, 2026 to review nominations and make recommendations to the FDA.
Yang and Goldspink (FEBS Lett 2002, PMID 12095637) established that the MGF E-peptide promotes myoblast proliferation and delays terminal differentiation through a receptor distinct from IGF-1R, separating MGF pharmacology from mature IGF-1. Kandalla et al. (Mech Ageing Dev 2011, PMID 21354439) showed the 24-aa MGF E-peptide activates human muscle progenitor cells and enhances their fusion potential even from older donors. Qin et al. (Mol Cell Biochem 2012, PMID 22875667) confirmed MGF drives satellite-cell proliferation while inhibiting differentiation by down-regulating MyoD and p21. Comprehensive reviews by Matheny, Nindl & Adamo (Endocrinology 2010, PMID 20130113) and Zabłocka, Goldspink et al. (Front Endocrinol 2012, PMID 23125840) summarize the evidence across muscle, cardiac and neural tissue and caution that MGF's receptor, in vivo pharmacokinetics, and safety profile remain incompletely characterized. No randomized controlled human trials of PEG-MGF have been published. MGF and IGF-1 analogs are prohibited at all times under the WADA Code.
Key references
Animal studies of full-length Tβ4 show accelerated dermal wound reepithelialization (Malinda et al., 1999, PMID 10469335), increased angiogenesis, improved cardiac function after ischemic injury via an ILK/Akt pathway (Bock-Marquette et al., Nature 2004, PMID 15565145), and corneal healing (Sosne & Kleinman review, 2015, PMID 26241398). The short Ac-LKKTETQ peptide sold as TB-500 was characterized analytically in the anti-doping literature as a substance with suspected doping potential (Esposito et al., 2012, PMID 22962027); controlled human efficacy trials of injected TB-500 do not exist. Full-length synthetic Tβ4 (RGN-259) has been evaluated in Phase II/III ophthalmic trials for dry eye disease and neurotrophic keratopathy with mixed results — one Phase III NK trial met healing endpoints, while a later European Phase III missed its primary endpoint. No clinically validated human injection dose exists for the short TB-500 peptide; all circulating dosing figures derive from vendor and forum protocols, not controlled trials.
PEG-MGF (Performance) and TB-500 (Recovery) are in different categories and target different biological pathways. This is a common pattern in multi-compound research protocols. Researchers should monitor the biomarkers from both profiles and watch for interactions listed in each compound’s contraindications. Consult a licensed healthcare provider before combining any research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Frequency
Dosing Notes
Half-life
Side Effects
Contraindications
Lab Testing
Key references
Disclosed Labs