Growth hormone secretagogue
Ipamorelin
A selective growth hormone secretagogue studied for its relatively clean release of growth hormone with less effect on appetite and stress hormones than earlier peptides.
What it is
Ipamorelin is a short synthetic pentapeptide that acts on the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus. It was designed to release growth hormone without the cortisol and prolactin rises seen with older secretagogues. It is not an approved medicine, has a short half-life of roughly two hours, and is prohibited in sport.
How it works
- 1
Binds the ghrelin/growth-hormone-secretagogue receptor in the pituitary gland.
- 2
Triggers release of growth hormone in pulses rather than a continuous rise.
- 3
Because growth hormone then drives IGF-1 production in the liver, effects on the whole body are indirect and slow.
- 4
Animal work suggests it is more selective than earlier secretagogues, with less effect on ACTH, cortisol and prolactin.
- 5
Its short half-life means growth-hormone release is brief, which is why research protocols used frequent dosing.
What it's studied for
Reported and studied effects
- Dose-dependent growth-hormone release in healthy volunteers
- Modest rises in IGF-1 reported in small short-term studies
- Less appetite stimulation than ghrelin itself in early comparisons
- No convincing evidence of meaningful body-composition change from human trials
Research protocol notes
Research context onlyResearch context only — no approved human protocol exists. Published pharmacokinetic studies used single subcutaneous doses in the microgram-per-kilogram range and measured growth-hormone pulses over hours. Long multi-week 'cycle' schedules circulating online have no controlled human evidence behind them.
These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.
Possible side effects and contraindications
Safety profile
Possible side effects
- Headache and flushing shortly after dosing, reported in early studies
- Increased hunger in some reports
- Water retention and joint discomfort reported anecdotally with growth-hormone-raising agents
- Long-term safety is unknown
Contraindications and cautions
- Not established
- Active or previous cancer should be discussed with a doctor, as growth hormone and IGF-1 can promote growth of some tumours
- Pregnancy, breastfeeding and childhood
- Prohibited in competitive sport
A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.
Evidence assessment
There are small, short pharmacokinetic and endocrine-response studies in humans, but no large or long-term trials of clinically meaningful outcomes.
References
- 01Raun et al., Ipamorelin, the first selective growth hormone secretagogue, Eur J Endocrinol 1998 — PubMed search
- 02Ipamorelin human pharmacokinetics — PubMed literature search
- 03World Anti-Doping Agency — Prohibited List
References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.
Related
Related peptides
Other entries in Growth hormone secretagogue.
Growth hormone secretagogue
CJC-1295
A modified growth-hormone-releasing hormone analogue whose albumin binding gives it an unusually long action. Studied in small human trials; not an approved medicine.
Growth hormone secretagogue
CJC-1295 (no DAC) + Ipamorelin blend
The classic growth-hormone stack in one vial: a GHRH fragment with a secretagogue, unapproved and prohibited in sport.
Growth hormone secretagogue
CJC-1295 (no DAC) / mod GRF 1-29
The short-acting sister of CJC-1295: a GHRH fragment that produces brief growth-hormone pulses instead of sustained elevation.