PEG-MGF is sold as a PEGylated form of mechano growth factor, a peptide named after a splice variant of the IGF-1 gene that muscle expresses after mechanical load. It is one of the most searched research peptides with no human record at all: not a trial, not a pharmacokinetic study, not a case series. This page sets out what the literature does and does not contain (searched 2026-10-11), the figures that circulate as recorded by a 2026 clinical review, how PEGylation complicates the milligram on the label, and the syringe arithmetic for the vials sold. It reports; it suggests no dose.
The arithmetic for any vial is on the PEG-MGF calculator; the unPEGylated form has its own calculator. The IGF-1 analogue most often named beside it is on the IGF-1 LR3 dosage page.
What the literature holds
| Search (2026-10-11) | Result |
|---|---|
| PubMed: PEG-MGF, PEG MGF, pegylated mechano growth factor | 5 records; none administers PEG-MGF |
| PubMed: "mechano growth factor" | 205 records; cell, animal and expression work |
| ClinicalTrials.gov, openFDA labels | No registration, no label naming PEG-MGF |
| 2026 clinical review (PMID 42395176) | Evidence tier D: "no peer-reviewed human studies" |
The 205 MGF records are mostly about the E-domain peptide in cells and animals: cardiac repair after infarction in rats, bone-defect healing, stem-cell migration, and the variant's expression in tumour tissue, including human prostate cancer. The review lists that last strand as a "theoretical proliferative concern" — preclinical, not a measured human harm, and stated here because it is the one safety question the literature raises.
The figures that circulate
The 2026 review is the only peer-reviewed paper found that writes down the online figures, which it presents as behavioural data, not recommendations:
| Pattern (as recorded) | Amount | Frequency | Length |
|---|---|---|---|
| Post-exercise | 200–400 mcg, SC or IM | 2–3 × a week, 30–60 min after training | 8–16 weeks, ~4 weeks off |
| Loading, step 1 | 100 mcg | not stated | 2 weeks |
| Loading, step 2 | 200 mcg | not stated | 2 weeks |
| Loading, step 3 | 300 mcg | not stated | 4 weeks |
| Maintenance | 200–400 mcg | daily | — |
The patterns rest on different assumptions about how long the molecule lasts: a two-or-three-times-a-week schedule implies a long-acting peptide, a daily one a short-acting peptide. No study has measured its duration, so neither assumption has a source.
What PEGylation does to the arithmetic
Attaching polyethylene glycol to a protein slows its clearance. The one human study of a PEGylated relative — Roche's RO5046013, a PEGylated full-length IGF-I given once to 62 volunteers — measured a half-life of 140 to 200 hours, and found it suppressed growth hormone less than the unmodified form. That is a different and much larger molecule; it shows what PEGylation can do, not what it does to MGF.
The label raises a separate problem. PEG chains are heavy, and the degree and site of PEGylation are not standardised between sellers, so a "2 mg" PEG-MGF vial may count the PEG in its milligrams. Every figure below divides the labelled milligrams by the water, which is all arithmetic can do; how much of that mass is peptide is unknown without an assay.
Units per vial
U-100 syringe, 1 unit = 0.01 mL. Units = amount in mcg ÷ concentration in mcg/mL × 100.
| Amount | 2 mg in 1 mL (2,000 mcg/mL) | 2 mg in 2 mL (1,000 mcg/mL) | 5 mg in 2 mL (2,500 mcg/mL) | 5 mg in 3 mL (1,667 mcg/mL) |
|---|---|---|---|---|
| 100 mcg | 5 | 10 | 4 | 6 |
| 200 mcg | 10 | 20 | 8 | 12 |
| 300 mcg | 15 | 30 | 12 | 18 |
| 400 mcg | 20 | 40 | 16 | 24 |
Stated as results: at 1,000 mcg/mL, 200 mcg of PEG-MGF is 20 units; at 2,500 mcg/mL it is 8 units.
Amounts per vial and per course
| Pattern | Total | 2 mg vials | 5 mg vials |
|---|---|---|---|
| One 200 mcg amount | 0.2 mg | 10 per vial | 25 per vial |
| Post-exercise, 200–400 mcg × 2–3 a week | 0.4–1.2 mg a week | one vial lasts 1.7–5 weeks | one vial lasts 4–12.5 weeks |
| Loading sequence, read as daily | 12.6 mg over 8 weeks | ≈6.3 | ≈2.5 |
The loading total assumes each step is daily, which the review's table does not state; read as three times a week it would be about 5.4 mg. Both figures are arithmetic on circulating numbers, not on a study.
What is not established
Everything clinical: whether PEG-MGF does anything in people, at what amount, by which route, how long it lasts, and what it does over months. The review's own conclusion for this tier is that claims rest on preclinical extrapolation and user narratives. PEG-MGF is not approved anywhere, and its class is prohibited in sport. Product and dose decisions belong with a clinician. The compound is covered in Medibact's PEG-MGF guide.
Sources and dates
Opened 2026-10-11: the 2026 review by Dominikowski et al. (PMC13322892), tables 1 and 2 and section 3.4.4.1; the abstract of Kletzl et al. 2017 (PMID 28110155); PubMed searches for the PEG-MGF name forms (5 records) and "mechano growth factor" (205) and their record titles; ClinicalTrials.gov and openFDA searches; the 2026 WADA Prohibited List in Tractatenblad 2026 no. 25, section S2.3. Units, per-vial and per-course arithmetic by this site. Corrections go to the contact page.