IGF-1 LR3 Capsules UK
1 product from 1 brand · free UK delivery · EU 3–7 days
Last reviewed · prices and listings checked by Free Muscle
IGF-1 LR3, also written Long R3 IGF-1, LR3-IGF-I or Long [Arg3]-IGF-I, is a recombinant analogue of human insulin-like growth factor 1: the 70-amino-acid IGF-1 sequence with arginine substituted for glutamate at position 3 and a 13-amino-acid extension on the N-terminus, 83 residues in all. It was engineered as a cell-culture reagent with weak binding to IGF-binding proteins. This page lists every brand of IGF-1 LR3 stocked at Free Muscle, compared on pack size, form and batch testing. Research use only, 18+.
What is IGF-1 LR3?
Native IGF-1 is a 70-amino-acid peptide hormone produced mainly by the liver in response to growth hormone. In blood it circulates almost entirely bound to IGF-binding proteins (IGFBPs), which control how much reaches the type 1 IGF receptor on tissues. In the early 1990s a group in Adelaide produced IGF-1 analogues in E. coli as fusion proteins with an N-terminal extension derived from porcine growth hormone, and found that swapping glutamate 3 for arginine sharply reduced binding to the IGFBPs. The long arginine-3 variant, LR3-IGF-I, was the most potent of the set in cell-culture assays because less of it was sequestered by binding proteins in the medium, even though it bound the IGF receptor itself less well than native IGF-1.
| Feature | Native IGF-1 | IGF-1 LR3 |
|---|---|---|
| Length | 70 amino acids | 83 amino acids |
| Residue 3 | Glutamate | Arginine |
| N-terminal extension | None | 13 residues: the N-terminal 11 residues of methionyl porcine growth hormone, followed by Val-Asn |
| Production | Made in the body, mainly by the liver | Recombinant fusion protein expressed in E. coli |
| Binding to IGF-binding proteins | High | Markedly reduced |
| Binding to the type 1 IGF receptor | Reference | About three-fold weaker |
| Licensed medicine | Mecasermin (recombinant native IGF-1), prescription only | None |
That is the compound's purpose: a laboratory reagent for growing and studying cells, and later a widely used supplement in serum-free cell-culture media for biopharmaceutical production. It has never been developed as a medicine, has never been through a human clinical trial, and has no approval anywhere. The related licensed medicine is mecasermin, which is native recombinant IGF-1 given by injection under prescription for a rare growth disorder. IGF-1 LR3 is not mecasermin, and as a peptide of 83 amino acids it would be broken down in the digestive tract if taken by mouth, which is one reason we describe our capsules as a research product and nothing more.
What the published research reports
Francis and colleagues (1992) described the E. coli expression system and compared the fusion analogues in rat L6 myoblasts and H35 hepatoma cells. All were more potent than native IGF-1 at stimulating protein and DNA synthesis in cells that secrete IGF-binding proteins, with Long [Arg3]-IGF-I the most potent, but in chicken embryo fibroblasts, which do not secrete binding proteins, it was less potent than IGF-1. The extra activity, in other words, came from evading binding proteins rather than from stronger receptor action.
Tomas and colleagues (1992) infused IGF-1 and its analogues into rats made catabolic with dexamethasone. LR3-IGF-I was about 2.5 times as potent as native IGF-1 at restoring body weight and nitrogen retention despite binding the type 1 IGF receptor three-fold less well, and the IGF peptides increased gut weight by up to 45 per cent. This is a rodent study of a drug-induced catabolic state.
The human evidence concerns native IGF-1 rather than LR3. Rosenbloom (2009), reviewing mecasermin, lists hypoglycaemia as its most frequent side effect, along with lymphoid tissue hyperplasia that can require tonsillectomy, accumulation of body fat and coarsening of facial features, and notes that the anti-apoptotic properties of IGF-1 are a concern for cancer pathogenesis in long-term therapy. Pollak (2008) reviews the considerable evidence that insulin and IGF signalling have important roles in neoplasia, to the point where blocking the IGF-1 receptor is a cancer-treatment strategy under study.
A long half-life is often claimed for IGF-1 LR3 online, but the animal data point the other way. In non-pregnant rats given an intravenous dose of labelled peptide, LR3-IGF-I was cleared from plasma roughly ten times faster than native IGF-1 and circulated mostly as free peptide rather than bound to binding proteins (Bastian et al., 1993). A later rat study, which took that faster clearance as its starting point, found that LR3 given by injection rather than by continuous infusion was much less potent, although still ahead of injected IGF-1 on several measures, and was barely equal to IGF-1 at reversing muscle loss in dexamethasone-treated rats (Tomas et al., 1996). We have found no published human pharmacokinetic study.
None of this is a claim about the capsules listed here. The potency data come from cell culture and rats, and the safety data come from a different molecule given by injection to patients under medical supervision.
Brands of IGF-1 LR3 we stock
- Free Muscle IGF-1 LR3, Growth Factor Peptide: Free Muscle brand, capsule form, 60 capsules per bottle. Every batch is assayed for identity and purity by Janoshik Analytical, with the certificate sent on request. The listing states the declared quantity per capsule where one is given; where it is not, no figure is stated here.
The collection currently holds one listing. Any other brand of IGF-1 LR3 stocked in future would be listed here with its capsule count, declared quantity and batch-certificate status. Other research peptides are gathered in the peptides collection.
How to compare them
Multiply the declared quantity per capsule by the capsule count for total peptide per bottle, and divide the listed price by that figure. Growth factors are usually quantified in micrograms rather than milligrams, so check the unit before comparing. Where no quantity is declared, no cost per unit can be calculated and you should treat the absence as a fact about the listing. For a peptide of this size, the identity test on the certificate, confirming the expected molecular mass, matters as much as the purity figure. See price per milligram for the general method.
Batch testing and certificates of analysis
A Certificate of Analysis for IGF-1 LR3 should report identity, normally by HPLC and mass spectrometry against the expected mass of the 83-residue peptide, and purity as a percentage, together with the batch number, the test date and the laboratory. Every Free Muscle batch is assayed by Janoshik Analytical, an independent laboratory; email us the batch number printed on your label with the product name and we send the certificate for that batch. For other brands, a certificate is shown only where the manufacturer supplies one for the batch we hold. A generic PDF without a batch number is a brochure, not a batch certificate, and a CAS number printed on a listing is not proof of identity either: one quoted online for IGF-1 LR3, 946870-92-4, belongs in PubChem to an unrelated lipid compound (CID 168009904, checked October 2026). See how we test and how to read a COA.
Where to buy IGF-1 LR3 in the UK: how to check a supplier
Whichever shop you buy IGF-1 LR3 from, check these five points before you order:
- A batch number and a certificate for that batch. The pack should carry a batch number, and the seller should be able to show a certificate of analysis for that same batch from a named laboratory, with the test date. Every Free Muscle-brand batch is assayed by Janoshik Analytical, and we send the certificate for your batch on request.
- The strength per capsule and the capsule count. With both figures you can work out the total milligrams in the pack and the price per milligram. If a listing does not state one of them, ask the seller before you order.
- Research-use labelling and an age check. A research compound should be sold for laboratory research use only, not for human consumption, to adults aged 18 or over, with no dosing or usage advice. That is how every listing here is sold.
- Prices in pounds sterling and tracked UK dispatch. UK delivery from us is free and tracked on every order, with no minimum spend, and usually arrives 2-3 working days after dispatch; orders placed before 2pm Monday to Friday are processed the same working day.
- A clear returns policy. Unopened items can be returned to us within 30 days.
Brand on this page: Free Muscle. The UK supplier checklist and how we test go into more detail.
Legal status in the UK
IGF-1 LR3 is not a licensed medicine in the UK and holds no MHRA marketing authorisation. It is not an authorised food supplement or novel food and cannot be sold for human consumption. Free Muscle supplies it for laboratory research only, to adults aged 18 or over. Under section S2 of the WADA Prohibited List, insulin-like growth factor 1 and its analogues are prohibited at all times, so IGF-1 LR3 is incompatible with tested sport. Our guide IGF-1 LR3: a cell-culture reagent, not a supplement sets out the regulatory position in more detail, and SARMs vs Peptides explains how the two classes differ in law and in research.
Storage and handling
Growth factor peptides are sensitive to heat and moisture. Keep the sealed bottle in a cool, dry place away from light, follow any storage instruction on the label, and reseal promptly after opening. Do not decant capsules into unlabelled containers. Record the batch number and receipt date. Keep out of reach of children and pets and apply normal laboratory good practice.
Delivery and returns
Free Muscle is the trading name of FreeMuscle, a business registered in Andorra, with UK operations and dispatch in Scunthorpe. Orders ship with free tracked UK delivery in plain packaging, and orders placed before 2pm Monday to Friday are processed the same working day. EU delivery takes 3 to 7 working days. Unopened items can be returned within 30 days. See delivery and our 30-day guarantee.
Related reading
- Do Oral Peptides Actually Work? The Honest Answer
- Insulin Grow research compound: A Complete Guide for Lab Research
- How to Read a Certificate of Analysis (COA)
References
- Francis GL, et al. Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency. J Mol Endocrinol. 1992;8(3):213-223. PMID: 1378742.
- Tomas FM, et al. Insulin-like growth factor-I (IGF-I) and especially IGF-I variants are anabolic in dexamethasone-treated rats. Biochem J. 1992;282(Pt 1):91-97. PMID: 1371669.
- Rosenbloom AL. Mecasermin (recombinant human insulin-like growth factor I). Adv Ther. 2009;26(1):40-54. PMID: 19198769.
- Pollak M. Insulin and insulin-like growth factor signalling in neoplasia. Nat Rev Cancer. 2008;8(12):915-928. PMID: 19029956.
- Bastian SE, et al. Plasma clearance and tissue distribution of labelled insulin-like growth factor-I (IGF-I) and an analogue LR3IGF-I in pregnant rats. J Endocrinol. 1993;138(2):327-336. PMID: 7693845.
- Tomas FM, et al. Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection. J Endocrinol. 1996;150(1):77-84. PMID: 8708565.
Last reviewed: October 2026.
Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice. Summaries of published research describe study findings and are not claims about any product.
Research guides
Frequently asked questions
Is IGF-1 LR3 legal in the UK?
Under UK law IGF-1 LR3 is not a controlled drug. It does, however, lack a medicines licence and any food supplement authorisation, so selling it for people to consume is not permitted. Free Muscle supplies it as a research reagent for laboratory use to adults only (18 and over). In sport, WADA bans it as an analogue of IGF-1.
What is the difference between IGF-1 LR3 and IGF-1?
IGF-1 LR3 is IGF-1 with two changes: arginine in place of glutamate at position 3 and a 13-amino-acid extension at the N-terminus. Those changes cut its binding to IGF-binding proteins, so in cell culture more of it stays free to act, which is why it is more potent in that setting. It binds the IGF receptor itself less well than native IGF-1, about three-fold less in one published comparison (Tomas 1992).
Is IGF-1 LR3 a peptide, a SARM or a hormone?
It is a peptide, an 83-amino-acid analogue of a peptide hormone. It is not a SARM, which is a small molecule acting at the androgen receptor, and it is not growth hormone, although IGF-1 is the main mediator of growth hormone's effects. It was designed as a cell-culture reagent and has never been developed as a medicine.
Has IGF-1 LR3 been tested in humans?
No clinical trials of IGF-1 LR3 have been published. The potency data come from cell culture and rodent studies. The human safety information on this page concerns mecasermin, native recombinant IGF-1 given by injection under prescription, where hypoglycaemia is the most frequent side effect and long-term cancer risk is a stated concern. Those findings are about a different molecule.
Does IGF-1 LR3 work as a capsule?
We do not claim that it does. An 83-amino-acid peptide taken by mouth is broken down by digestive enzymes, and all the research on IGF-1 LR3 used it in cell-culture medium or by infusion in animals. Our capsules are supplied for laboratory research. Our article on oral peptides explains the absorption problem without spin.
How do I verify the batch of IGF-1 LR3 I have?
Read the batch number off the label and send it to us by email, naming the product; for Free Muscle brand IGF-1 LR3 we reply with that batch's Janoshik Analytical certificate, which gives identity and purity. The certificate's batch number should be the one on your bottle. Listings from other brands carry a certificate only where the manufacturer supplied one for the batch we hold.
What is the difference between IGF-1 LR3 and IGF-1 DES?
Both are modified forms of IGF-1 that bind IGF-binding proteins poorly. DES(1-3) IGF-1 is native IGF-1 missing its first three amino acids; LR3 keeps the full sequence, carries arginine in place of glutamate at position 3 and adds a 13-amino-acid extension. In cell lines that secrete binding proteins the two ranked at the top of the potency order, ahead of native IGF-1 (Francis 1992), and in dexamethasone-treated rats each showed roughly two and a half times the potency of IGF-1 (Tomas 1992). Neither is a medicine, and both fall under WADA section S2.
What is the half-life of IGF-1 LR3?
No human figure can be given, because we have found no published human study of IGF-1 LR3. In rats, injected LR3 was cleared from the blood faster than native IGF-1, not more slowly, and circulated mostly as free peptide because it binds poorly to the proteins that hold IGF-1 in the circulation (Bastian 1993). Its extra potency in cell culture comes from escaping those binding proteins, not from lasting longer. We could not trace the longer half-life figures quoted online to a published source.
Where can I buy IGF-1 LR3 in the UK?
On this page you can compare every IGF-1 LR3 listing we stock (at present from Free Muscle). Every UK order ships free with tracking, with no minimum spend, and usually arrives 2-3 working days after dispatch. Everything here is supplied for laboratory research use only, not for human consumption, to adults aged 18 or over.
How fast is UK delivery?
UK delivery is free and tracked on every order, with no minimum spend, and usually arrives 2-3 working days after dispatch. Faster tracked UK delivery costs £6 and usually takes 1-2 working days. Orders placed before 2pm Monday to Friday are processed the same working day.
Do you deliver to Romania and the rest of the EU?
Yes. Orders to Romania and other EU countries travel by our paid, tracked international service and usually arrive 3-7 working days after dispatch; delivery to the rest of the world usually takes 5-14 working days. Prices are in pounds sterling (GBP). Rules differ in other countries, so check local law before ordering for delivery abroad.
Can I return an order?
Yes: unopened items can be returned within 30 days. Our guarantee page has the full policy.
Is there a discount when I buy more than one?
Yes, on Free Muscle-brand products: 5% off automatically when your cart holds 2 of them and 10% off with 3 or more, applied in the cart. The offers do not combine.