What it is
Ipamorelin is a ghrelin mimetic: it acts on the same receptor as ghrelin, a hormone that signals the pituitary gland to release growth hormone. At the same time it lowers somatostatin, the signal that normally holds that release back.
Why selectivity matters
Other compounds in this class, such as GHRP-2 and GHRP-6, also raise cortisol, prolactin and appetite. Ipamorelin produces its growth hormone signal without meaningfully affecting those, which is why it is considered the mildest and cleanest option of the group.
Two pathways, one pulse
The pituitary can be signalled through two different receptors. GHRH analogues such as CJC-1295 tell it to release; ghrelin mimetics such as ipamorelin tell it to release and remove the brake at the same time. One of each produces a considerably larger pulse than either alone, which is why ipamorelin is usually studied together with a GHRH analogue.
- Highly selective growth hormone release
- No meaningful effect on cortisol or prolactin
- No marked increase in appetite
- Half-life of about 2 hours
What the evidence tells us.
Ipamorelin is an investigational peptide. Human clinical data are limited and its long-term safety and effectiveness have not been established. It is not approved by major regulatory agencies for muscle growth, recovery, fat loss or anti-ageing.