IGF-1 LR3

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 slightly less well than native IGF-1.

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.

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. See how we test and how to read a COA.

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. For how peptides and SARMs differ in law and in research, see SARMs vs Peptides.

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 a UK company, FreeMuscle LTD of 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
• Human Growth Hormone Research Uses: A Complete Guide for Lab Studies
• How to Read a Certificate of Analysis (COA)

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• Research Peptides

IGF-1 LR3 is sold for laboratory research use only. It is not a licensed medicine, has not been evaluated by the MHRA, EMA or FDA, is not a food supplement and is not for human consumption. Customers must be 18 or over. Nothing on this page is medical advice or dosing guidance, and the published findings summarised above describe cell cultures, animals and a different licensed medicine, not the products listed.

Research guides

• IGF-1 LR3: a cell-culture reagent, not a supplement