Encyclopedia entry · GH Secretagogues
IGF-1 LR3
Long-R3 Insulin-like Growth Factor 1
IGF-1 LR3 is a synthetic analogue of Insulin-like Growth Factor 1 with two modifications: a 13-amino-acid N-terminal extension (the Long peptide tag), and a substitution at position 3 (Glu to Arg). These changes dramatically reduce binding to IGF-binding proteins (IGFBPs), extending in-vivo half-life from minutes to roughly 20 to 30 hours.
What the molecule is
- · Synthetic IGF-1 variant with arginine substitution at position 3 and N-terminal extension.
- · Reduced affinity for IGFBPs (Insulin-like Growth Factor Binding Proteins) extends half-life.
- · Mitogenic and anabolic in laboratory cell-culture and animal-model work.
- · Distinct from clinical IGF-1 (Mecasermin), which is the unmodified hormone used in paediatric IGF deficiency.
What the literature shows
- · Originally engineered for laboratory cell-culture growth-supplement use.
- · Animal-model evidence for muscle protein synthesis and hypertrophy.
- · Insulin-like hypoglycaemia effects reported in animal work.
- · No phase III human trials. Not licensed by any Western regulator.
UK regulatory status
- · Not a controlled drug under the Misuse of Drugs Act 1971.
- · Not scheduled under the Psychoactive Substances Act 2016.
- · No UK marketing authorisation as a medicine.
- · Research-tier in all Western jurisdictions.
Where UK researchers source IGF-1 LR3
See PeptideClear Trust Index →Ranked by CoA Trust tier (strong, partial, weak). Editorial commentary on retailers that list IGF-1 LR3 or compounds in the same category. We take no commission, referral fee or payment from anyone listed here.
Researchers wanting named-stack bundles (Wolverine, KLOW, Glow) and CoAs that can be QR-verified to a named third-party lab.
Research peptide retailer · Wolverine Stack £29.99, BPC-157 single from £14.99
Nottingham-based research peptide retailer (Bio Research Ltd, since 2024). Bundles and stacks are the hero SKU (Wolverine BPC-157 + TB-500, Tesamorelin + Ipamorelin 3:1, KLOW, Glow). Janoshik third-party CoAs published per batch with QR-code verification. 10-vial bulk packs alongside singles. Wholesale tier above 11 vials.
Researchers who want transparent third-party HPLC batch documents and a less hyped brand voice.
Research peptide retailer · Per peptide, varies
UK research peptide retailer with third-party HPLC plus transparent batch documentation. Plays the credibility lane alongside Pure Peptides UK and Tide Labs.
Best for HPLC verification per product
Research peptide retailer · Per peptide, varies
UK research peptide retailer with HPLC-verified purity claims and CoAs included on orders. Operates under research-use-only framing.
Best for per-batch CoA library
Research peptide retailer · BPC-157 5mg £13.99, TB-500 5mg £36
Long-established UK research peptide supplier. 12 years trading, 15,000+ customers. Operates a public CoA subdomain (coa.purepeptidesuk.com) with downloadable per-batch certificates linked from every PDP. Dual-tier purity (Standard vs Premium with endotoxin LAL + heavy-metal testing on Premium).
Best for public per-batch third-party test reports you can view before ordering
Research peptide retailer · Per peptide, varies
UK-based research peptide retailer trading as Midshire Labs Ltd, with a recovery and longevity focused range, 99%+ purity claims and a public bank of per-batch third-party test reports. All products are framed as research use only.
Researchers who weight UKAS lab accreditation specifically and want the loudest external-verification claim in the segment.
Research peptide retailer · Per peptide, varies
UK research peptide retailer leaning on UKAS-verified HPLC as the sole-in-UK trust claim. Narrower catalogue than UKPeptides or Pure Peptides UK but the lab-verification angle is the loudest in the segment.
Where to learn more
- · PubMed search: "IGF-1 LR3" and "Long R3 IGF-1".
- · Francis GL et al. original development papers.
- · Our function hub: GH Secretagogues.
PeptideClear does not sell, dispense, prescribe, or recommend IGF-1 LR3 for any specific person. This page is editorial commentary on the published preclinical and clinical research literature and the UK retail landscape.
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