Mecasermin
Also known as: Increlex, rhIGF-1, Recombinant human IGF-1, Recombinant insulin-like growth factor 1, Somatomedin C
Key Facts: Mecasermin
- Category
- Growth Hormone
- FDA Status
- FDA Approved
- Clinical Status
- FDA Approved - Increlex (2005) for growth failure in children 2 years and older with severe primary IGF-1 deficiency or GH gene deletion with neutralizing GH antibodies. Not a substitute for GH. Also approved in the EU. WADA: prohibited at all times under S2.3, which names mecasermin.
- Banned in Sport (WADA)
- Prohibited at all times under WADA S2.3 (growth factors), where mecasermin is named as IGF-1.
- Administration
- Subcutaneous injection, rotating sites, within about 20 minutes before or after a meal or snack
- Typical Dose
- 0.04-0.08 mg/kg twice daily to start
- Frequency
- Twice daily
- Duration
- Long-term, until growth plates close (closed epiphyses are a contraindication)
How does Mecasermin work?
Normally, growth hormone binds receptors in the liver and other tissues and triggers IGF-1 production. IGF-1 then activates the type 1 IGF receptor on bone, cartilage and other cells, driving growth. In Laron syndrome the GH receptor is broken, so GH levels are high but IGF-1 stays low. Mecasermin skips the broken step and supplies IGF-1 directly. Because the IGF-1 receptor is a close relative of the insulin receptor, and because IGF-1 can also bind the insulin receptor at higher levels, it lowers blood sugar. That is why the label says to give it within about 20 minutes of a meal or snack. It is mostly carried by IGF binding protein 3 in blood, and its clearance depends on IGFBP-3 levels; the label reports a mean terminal half-life of about 5.8 hours in children with severe primary IGF-1 deficiency.
What does the research show?
The approval rests on five pooled studies (four open-label, one placebo-controlled) in 71 children with severe primary IGF-1 deficiency, 87% of whom had Laron syndrome. Height velocity rose from 2.8 cm per year before treatment to 8.0 cm per year in year 1, then settled around 4.5 to 5.8 cm per year in later years, still above baseline. Height scores improved but these children stayed very short (mean height SDS went from -6.7 to about -5.2 after 8 years), so it helps rather than normalizes. Hypoglycemia was reported in 42% of children at least once, and tonsillar hypertrophy in 15%. The label carries warnings for hypoglycemic seizures, anaphylaxis, intracranial hypertension, slipped capital femoral epiphysis (added July 2025), scoliosis progression, and postmarketing reports of malignant neoplasms; malignancy is a contraindication. Ownership changed recently: Eton Pharmaceuticals bought Increlex from Ipsen in December 2024 and in 2025 licensed rights outside the US to Esteve. Adult use, anti-aging use, and bodybuilding use are off-label and unsupported by trials.
FDA Approval Studies
This peptide is FDA approved. Below are the key clinical trials that supported its approval.
Pooled Increlex studies in severe primary IGFD
Tercica (now Eton Pharmaceuticals) • Pooled open-label and placebo-controlled studies
71
Up to 8 years
Annual height velocity versus pre-treatment
- ✓Height velocity 2.8 cm/year before treatment vs 8.0 cm/year in year 1
- ✓Year 2 height velocity 5.8 cm/year, around 4.3-4.8 cm/year by years 4-8
- ✓Height SDS improved from -6.7 to about -5.2
- ✓Hypoglycemia in 42%, tonsillar hypertrophy in 15%
What doses have been studied?
Typical Dosingⓘ
Community experience
0.04-0.08 mg/kg twice daily to start
0.04-0.12 mg/kg twice daily
Twice daily
Labeled doses are weight-based and pediatric. The dose goes up in 0.04 mg/kg steps after at least a week if there is no hypoglycemia. A dose should be skipped if the child cannot eat. There is no approved adult dose.
Research Dosingⓘ
Scientific studies
FDA-approved labeled dosing (prescription only, pediatric)
Doses from Studies
0.04-0.08 mg/kg twice daily, titrated to max 0.12 mg/kg twice daily
FDA Approved Labeling - Increlex prescribing information (revised 07/2025), section 2.1 ↗
Duration
Long-term, until growth plates close (closed epiphyses are a contraindication)
Administration
Subcutaneous injection, rotating sites, within about 20 minutes before or after a meal or snack
When and how is Mecasermin taken?
Best Time to Take
Shortly before or after a meal or snack, twice daily
Twice daily, morning and evening with meals
Food Recommendation
Take with food
Why This Timing?
IGF-1 lowers blood sugar like insulin, so the label requires dosing within about 20 minutes of food and says to skip the dose if the meal is skipped.
What are the side effects of Mecasermin?
Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.
- ●Hypoglycemia (42% in trials), including hypoglycemic seizures
- ●Tonsillar and adenoidal hypertrophy, snoring, sleep apnea
- ●Injection site lipohypertrophy, bruising, pain
- ●Allergic reactions, including rare anaphylaxis
- ●Intracranial hypertension (headache, vision changes)
- ●Slipped capital femoral epiphysis (hip or knee pain, limp)
- ●Progression of scoliosis
- ●Malignant neoplasms reported postmarketing (contraindicated with active or past malignancy)
- ●Ear fluid and hearing problems
- ●Benzyl alcohol preservative not for infants
References
- https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/021839s033lbl.pdf
- https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/021839s031lbl.pdf
- https://www.thepharmaletter.com/esteve-signs-a-licensing-agreement-with-eton-pharma
Research This Peptide Further
Frequently Asked Questions
What does Mecasermin do?
Mecasermin is recombinant human IGF-1, identical to the 70-amino-acid hormone your liver makes in response to growth hormone. Sold as Increlex, it was FDA approved in 2005 for a narrow group: children with severe primary IGF-1 deficiency (mostly Laron syndrome) or a growth hormone gene deletion with antibodies against GH. In those kids it is the only thing that works, because GH cannot do its job. It is not a GH substitute, and its real risks (low blood sugar, tonsil overgrowth, cancer warnings) are why it stays a specialist drug.
How does Mecasermin work?
Normally, growth hormone binds receptors in the liver and other tissues and triggers IGF-1 production. IGF-1 then activates the type 1 IGF receptor on bone, cartilage and other cells, driving growth. In Laron syndrome the GH receptor is broken, so GH levels are high but IGF-1 stays low. Mecasermin skips the broken step and supplies IGF-1 directly. Because the IGF-1 receptor is a close relative of the insulin receptor, and because IGF-1 can also bind the insulin receptor at higher levels, it lowers blood sugar. That is why the label says to give it within about 20 minutes of a meal or snack. It is mostly carried by IGF binding protein 3 in blood, and its clearance depends on IGFBP-3 levels; the label reports a mean terminal half-life of about 5.8 hours in children with severe primary IGF-1 deficiency.
Is Mecasermin FDA approved?
Yes, Mecasermin is FDA approved. FDA Approved - Increlex (2005) for growth failure in children 2 years and older with severe primary IGF-1 deficiency or GH gene deletion with neutralizing GH antibodies. Not a substitute for GH. Also approved in the EU. WADA: prohibited at all times under S2.3, which names mecasermin.
Is Mecasermin banned in sport?
Prohibited at all times under WADA S2.3 (growth factors), where mecasermin is named as IGF-1.
What are the side effects of Mecasermin?
Reported side effects include: Hypoglycemia (42% in trials), including hypoglycemic seizures, Tonsillar and adenoidal hypertrophy, snoring, sleep apnea, Injection site lipohypertrophy, bruising, pain, Allergic reactions, including rare anaphylaxis, Intracranial hypertension (headache, vision changes). Individual responses vary based on dosage, duration, and personal health factors.
What is the typical dose of Mecasermin?
Community-reported common dose: 0.04-0.08 mg/kg twice daily to start (Twice daily). Range: 0.04-0.12 mg/kg twice daily. Administration: Subcutaneous injection, rotating sites, within about 20 minutes before or after a meal or snack. Prescription drug. Dose set by prescriber per label. Not medical advice.
Related Peptides
Peptides commonly compared with Mecasermin or used in similar applications.
HGH (Somatropin)
FDAHuman growth hormone is the real thing rather than a secretagogue: a 191-amino-acid protein identical to what your pituitary makes, produced recombinantly since the 1980s. It is a properly approved medicine for growth hormone deficiency, and it is also the most misused compound in this entire space. Almost everything you read about HGH for anti-aging or physique traces back to a single small 1990 study whose own author later disowned how it was used.
Growth HormoneMK-677
Clinical TrialsMK-677 (ibutamoren) is not actually a peptide, it is a small, orally active non-peptide molecule that mimics ghrelin, your hunger and growth-hormone hormone. Taken as a daily pill, it reliably pushes up growth hormone and IGF-1 levels, which is why it is popular for muscle and recovery. It has been through real human trials but was never approved as a drug, and the trials that mattered most for older adults and Alzheimer's came up short.
Growth HormoneGHRP-6
Clinical TrialsGHRP-6 is a synthetic six-amino-acid peptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) that tricks the body into releasing its own growth hormone. It was one of the first growth hormone secretagogues ever made, and the hunt to find out why it worked led scientists straight to the discovery of ghrelin. It has no approval as a drug anywhere and is used only as a research compound.
Growth HormoneGHRP-2
Clinical TrialsGHRP-2 (generic name pralmorelin) is a synthetic hexapeptide growth hormone secretagogue and a second-generation cousin of GHRP-6. It prompts the pituitary to release growth hormone and is the one peptide in this family with an actual regulatory approval: it is licensed in Japan as a diagnostic agent for growth hormone deficiency. Outside that narrow diagnostic use it has no approval and is sold elsewhere only as a research compound.
Growth HormoneIGF-1 DES
PreclinicalIGF-1 DES is insulin-like growth factor 1 with its first three amino acids chopped off, leaving a 67-residue peptide. That small cut makes it bind poorly to the IGF binding proteins that normally keep IGF-1 in check, so more of it reaches the receptor and it acts stronger, but shorter. It occurs naturally in small amounts (it was first isolated from human fetal brain tissue) and is sold online as a muscle-building research peptide. There are no human trials of it at all, so everything said about it in people is extrapolation.
Growth HormoneTesamorelin
FDATesamorelin is a stabilized analog of growth-hormone-releasing hormone (GHRH 1-44) with a chemical modification that protects it from rapid breakdown. It is FDA-approved (brand name Egrifta) to reduce excess visceral abdominal fat in people with HIV-associated lipodystrophy, which makes it one of the few growth-hormone-axis peptides with a real approval behind it. Its evidence base is solid for that specific population and thinner for the general anti-aging and fat-loss uses it gets promoted for online.
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