Growth hormone axis
Ipamorelin vs Sermorelin: Research Comparison
Ipamorelin and sermorelin both lead to growth hormone release, through different receptors. Ipamorelin acts on the ghrelin receptor. Sermorelin is the first 29 amino acids of GHRH and acts on the GHRH receptor.
Side-by-side comparison
| Attribute | Ipamorelin | Sermorelin |
|---|---|---|
| What it is | Synthetic five-amino-acid peptide | First 29 amino acids of human GHRH (GRF 1-29) |
| Receptor | Ghrelin receptor (GHS-R1a) | GHRH receptor |
| Time in the blood | Half-life about two hours in healthy men | Short-lived, like natural GHRH |
| Licensed history | Never licensed | Licensed in the US from 1990; discontinued by the manufacturer in 2008 |
| Adult data | Pharmacokinetic study in healthy men; phase 2 trial after bowel surgery | Small uncontrolled studies |
Detailed analysis
Ipamorelin (NNC 26-0161) was developed by Novo Nordisk. In pigs it released growth hormone without raising ACTH or cortisol (Raun et al., 1998), and in healthy men it produced a short burst of growth hormone with a half-life of about two hours (Gobburu et al., 1999). A phase 2 placebo-controlled trial in 114 adults after bowel surgery found no clear difference from placebo (Beck et al., 2014).
Sermorelin (formerly sold as Geref) was a licensed medicine in the US: approved in 1990 as a test of the pituitary's ability to release growth hormone, and in 1997 for children with idiopathic growth hormone deficiency. The manufacturer discontinued it in 2008, and the FDA later determined it had not been withdrawn for reasons of safety or because it did not work. In adults the evidence is thin: an uncontrolled six-week study in 11 healthy men aged 64 to 76 found more overnight growth hormone release but no change in IGF-1 or in muscle and fat measured by body scan (Vittone et al., 1997).
Because sermorelin acts through the pituitary, its effect stays under the body's normal controls on growth hormone. The research materials supplied here are not licensed products.
Key differences
- ·Ipamorelin acts on the ghrelin receptor; sermorelin acts on the GHRH receptor.
- ·Sermorelin was a licensed US medicine until 2008; ipamorelin has never been licensed.
- ·Ipamorelin's half-life in healthy men was about two hours; sermorelin is short-lived like natural GHRH.
- ·Adult data for both are limited to small studies.
Research summary
Ipamorelin evidence is pig and rat studies (Raun et al., 1998) and two human studies. Sermorelin has a past licensed record in children (Thorner et al., 1996) and small uncontrolled studies in adults (Vittone et al., 1997). Neither has long-term adult safety data. Supplied for laboratory research use only.