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Classes

IGF & growth factors

Insulin-like growth factor analogs, splice variants and growth hormone fragments.

6 compounds in this class. 1 approved by the FDA for at least one indication. 3 have no published human trial data.

Guides in this class

All 6 IGF & growth factors compared

CompoundEvidenceReported rangeHalf-lifeStatus
HGH Fragment 176-191
The C-terminal fragment of human growth hormone that carries its fat-metabolising activity without the growth-promoting portion.
 Preliminary human 250-500 mcg ~30 minutes Research only
IGF-1 DES
A truncated IGF-1 variant missing the first three residues, roughly ten times more potent than native IGF-1 but very short-acting.
 Animal models only 50-150 mcg ~20-30 minutes Research only
IGF-1 LR3
An IGF-1 analog modified to evade binding proteins, giving it far longer activity than native IGF-1.
 Animal models only 20-50 mcg ~20-30 hours Research only
MGF
A splice variant of IGF-1 expressed by muscle in response to mechanical loading and damage.
 Animal models only 100-200 mcg ~5-7 minutes Research only
PEG-MGF
Mechano growth factor with a polyethylene glycol chain attached, extending its circulating half-life from minutes to days.
 Animal models only 200-400 mcg ~48-72 hours Research only
Somatropin
Recombinant human growth hormone itself, the reference compound every secretagogue on this site is compared against.
 Regulator approved 200 mcg - 1 mg ~3-5 hours (subcutaneous) Approved

Head-to-head comparisons

AOD-9604 vs HGH Fragment 176-191HGH Fragment 176-191 vs IGF-1 LR3HGH Fragment 176-191 vs SemaglutideIGF-1 DES vs IGF-1 LR3IGF-1 DES vs MGFIGF-1 LR3 vs MGFIGF-1 LR3 vs PEG-MGFMGF vs PEG-MGFSermorelin vs SomatropinCJC-1295 vs SomatropinMK-677 vs SomatropinIpamorelin vs Somatropin

IGF & growth factors: common questions

What are IGF & growth factors?

Insulin-like growth factor analogs, splice variants and growth hormone fragments. This class has 6 compounds in our directory.

Which IGF & growth factors are FDA approved?

Somatropin is FDA approved for at least one indication. The others are not approved.

Which IGF & growth factors have the strongest evidence?

By evidence level and number of human studies: Somatropin (regulator approved, ~200 human studies); HGH Fragment 176-191 (preliminary human, ~3 human studies); MGF (animal models only, ~1 human studies).

Can compounding pharmacies make these?

HGH Fragment 176-191, IGF-1 DES, IGF-1 LR3, MGF, PEG-MGF are not FDA approved and not on the 503A bulks list, so there is no routine legal path to compound them. Material sold online is labelled for research use only. Status checked against FDA lists in October 2026.

References

Regulatory and primary sources

  1. FDA: Bulk drug substances that may present significant safety risks (Category 2 and withdrawn nominations) ↗ · content current as of April 22, 2026; checked October 18, 2026
  2. FDA: Bulk drug substances used in compounding under section 503A ↗ · how the 503A categories work
  3. FDA: Unapproved drugs ↗ · status of products sold "for research use only"
  4. WADA Prohibited List ↗ · peptide hormones and growth factors, class S2
  5. PubMed (National Library of Medicine) ↗ · source of every literature reference on this site

Published literature

  1. Rahman OF, Lee SJ, Seeds WA. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.J Am Acad Orthop Surg Glob Res Rev 2026.PubMed 41490200 · doi:10.5435/JAAOSGlobal-D-25-00236
  2. Wilding J. AOD-9604 Metabolic.Curr Opin Investig Drugs 2004.PubMed 15134286
  3. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.Sports Med 2026.PubMed 41966639 · doi:10.1007/s40279-026-02437-0
  4. Jensen MD. Potential role of new therapies in modifying cardiovascular risk in overweight patients with metabolic risk factors.Obesity (Silver Spring) 2006.PubMed 16931496 · doi:10.1038/oby.2006.294
  5. Halford JC. Obesity drugs in clinical development.Curr Opin Investig Drugs 2006.PubMed 16625817
  6. Khan A, Raza S, Khan Y, et al.. Current updates in the medical management of obesity.Recent Pat Endocr Metab Immune Drug Discov 2012.PubMed 22435392 · doi:10.2174/187221412800604644
  7. Thevis M, Schänzer W. Analytical approaches for the detection of emerging therapeutics and non-approved drugs in human doping controls.J Pharm Biomed Anal 2014.PubMed 24906629 · doi:10.1016/j.jpba.2014.05.020
  8. Zieba R. [Obesity: a review of currently used antiobesity drugs and new compounds in clinical development].Postepy Hig Med Dosw (Online) 2007.PubMed 17971763
  9. Espinosa G, Esposito R, Kazzazi A, et al.. Vitamin D and benign prostatic hyperplasia -- a review.Can J Urol 2013.PubMed 23930605
  10. Werther GA, Russo V, Baker N, et al.. The role of the insulin-like growth factor system in the developing brain.Horm Res 1998.PubMed 9554468 · doi:10.1159/000053066
  11. Ricort JM, Binoux M. Insulin-like growth factor (IGF) binding protein-3 inhibits type 1 IGF receptor activation independently of its IGF binding affinity.Endocrinology 2001.PubMed 11145572 · doi:10.1210/endo.142.1.7915
  12. Forbes B, Szabo L, Baxter RC, et al.. Classification of the insulin-like growth factor binding proteins into three distinct categories according to their binding specificities.Biochem Biophys Res Commun 1988.PubMed 2973786 · doi:10.1016/s0006-291x(88)80032-9
  13. Li YM, Schacher DH, Liu Q, et al.. Regulation of myeloid growth and differentiation by the insulin-like growth factor I receptor.Endocrinology 1997.PubMed 8977425 · doi:10.1210/endo.138.1.4847
  14. Pamuklar ZN, Chen J, Muehlbauer M, et al.. Necdin-E2F4 interaction provides insulin-sensitizing effect after weight loss induced by gastric bypass surgery.Surg Obes Relat Dis 2013.PubMed 22138333 · doi:10.1016/j.soard.2011.10.014

Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.