IGF-1 LR3 is a synthetic version of natural IGF-I with a few additional modifications having been made, specifically the replacement of glutamine at the 3 position with arginine- hence the LR3 nomenclature, as well as the addition of 13 amino acids to the IGF-I peptide chain, in effect lengthening it. In a nutshell, those modifications explain how to peptide came to be known as IGF-1 LR3.

Natural IGF-I consists of a 70 amino acid chain sequence, whereas synthetic IGF-1 LR3 consists of 83.

The modifications made to IGF-1 LR3 result in significantly increased potency, and an increase in the half-life of the peptide hormone, from an average of 13 hours to between 20 and 30 hours.

Effects Of IGF-1 LR3 Use

The primary use of synthetic IGF-I peptides today are in athletic disciplines, more specifically bodybuilding and other sports where increases muscle mass is desired. It can help with accrual of lean muscle mass by promoting protein synthesis and positive nitrogen balance.

In addition to this, the rate of protein breakdown is reduced, along with enhanced glucose uptake into cells and the recruitment of fats for use as energy. In turn, the body emphasizes utilizing fat for energy whilst glucose is shuttled into muscle cells to support growth and performance.

One interesting trait about IGF-1 LR3 is the fact that in addition to being used induce hyper trophy, it also promotes hyperplasia and mitogenesis-creation of new muscle cells altogether. Thus, its effects can be considered more complete than that brought about by growth hormone signaled IGF-I release.

This possibly indicates the fact that the IGF-1 LR3 can influence the expression of proteins at the genetic level, giving it further utility in the management of wasting disease and more efficient protein synthesis rates.

IGF-1 LR3 Pharmacology

IGF-1 LR3 interacts with IGF-I receptors in the same manner that natural IGF-I would, to elicit increased protein synthesis rates, but also induces changes at the genetic level. However, the magnitude of its effect is far greater owing to the fact that it binds much weaker to IGF-I binding proteins which typically inactivate a large amount of the natural hormone. This reduced binding means that a much larger amounts of unbound hormone is able to elicit effect.

IGF-1 LR3 Dosage

While IGF-1 is produced naturally in the body throughout an individual’s life, IGF-1 LR3, being a synthetic version with a different potency and pharmacokinetic properties should not be used indefinitely. Doses used for research studies range from between 20 to 120 µg daily, for a maximum period of 50 days. Subsequently, an off period equivalent to 50 to 100% of the time on is mandatory before attempting a subsequent cycle.

Its long half-life makes it unnecessary for frequent injections, and works perfectly with the intramuscular mode of administration.

Possible Untoward Effects Of IGF-1 LR3

IGF-1 LR3 shares many of the same possible adverse effects as growth hormone does, and also shares similarities to insulin’s side effects. While these are more likely at higher doses, you need to keep in mind the following:

Risk of hypoglycemia – IGF-1 LR3 inhibits the transport and usage of glucose for energy, favoring fats for ATP generation. While fat does a fair job of powering the body, it is not as efficient as glucose. Low blood sugar is a possibility, making it necessary to monitor blood glucose levels while using it. This is especially true in athletes that may be simultaneously using insulin.

Increased risk of malignancies – this includes accelerating the growth of otherwise benign tumors, increasing the risk of other cancers, as well as a growth of internal organs. You need to take extra precautions if you have a family history of any of the above, or may need to avoid it altogether.


IGF-1 LR3 is an advanced level peptide that should only be used by athletes who have experience using several cycles of anabolic hormones previously, or have tried HGH but are looking for any enhanced experience.