Ipamorelin
| Type | Growth hormone secretagogue |
|---|---|
| Class | GHRP (Ghrelin mimetic) |
| Amino Acids | 5 (pentapeptide) |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH₂ |
| Molecular Weight | 711.85 g/mol |
| CAS Number | 170851-70-4 |
| Status | Research compound |
Ipamorelin is a synthetic pentapeptide that functions as a selective growth hormone secretagogue. It stimulates the release of growth hormone from the pituitary gland by mimicking ghrelin and binding to the growth hormone secretagogue receptor (GHS-R). Ipamorelin is notable for its selectivity, producing growth hormone release with minimal effect on cortisol, prolactin, or appetite.
Development
Ipamorelin was developed by Novo Nordisk in the 1990s as part of research into growth hormone releasing compounds. It emerged from efforts to create more selective secretagogues with fewer side effects than earlier compounds like GHRP-6.
Mechanism of Action
Ipamorelin works through multiple mechanisms:
GHS Receptor Activation
- Binds to growth hormone secretagogue receptor (GHS-R1a)
- Mimics the action of endogenous ghrelin
- Triggers calcium signaling in somatotroph cells
- Stimulates growth hormone release from pituitary
Selectivity Profile
Unlike other GHRPs, ipamorelin demonstrates high selectivity:
- Minimal effect on ACTH and cortisol levels
- Does not significantly increase prolactin
- Less appetite stimulation than GHRP-6
- No effect on aldosterone, FSH, or LH
Comparison with Other GH Peptides
| Peptide | GH Release | Cortisol | Prolactin | Appetite |
|---|---|---|---|---|
| Ipamorelin | Moderate | Minimal | Minimal | Low |
| GHRP-6 | High | Moderate | Moderate | High |
| GHRP-2 | High | Moderate | Moderate | Moderate |
| Hexarelin | Very High | High | High | Moderate |
Research Applications
Ipamorelin has been studied in various research contexts:
Growth Hormone Research
- GH deficiency models
- Age-related GH decline studies
- Pituitary function assessment
Bone Research
- Bone mineral density studies
- Fracture healing models
- Osteoporosis research
Metabolic Research
- Body composition studies
- Lipid metabolism
- Insulin sensitivity
Combination Protocols
In research settings, ipamorelin is often studied in combination with GHRH analogs:
- Ipamorelin + CJC-1295: Synergistic GH release
- Ipamorelin + Mod GRF 1-29: Enhanced pulsatile release
The combination of a GHRP (ipamorelin) with a GHRH analog can produce greater GH release than either compound alone, as they work through complementary mechanisms.
Related Compounds
- GHRP-2 – Another growth hormone secretagogue
- GHRP-6 – Earlier GHRP with appetite effects
- CJC-1295 – GHRH analog often combined with ipamorelin
- Growth Hormone Peptides – Overview category
References
- Raun K, et al. "Ipamorelin, the first selective growth hormone secretagogue." Eur J Endocrinol. 1998.
- Johansen PB, et al. "Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats." Growth Horm IGF Res. 1999.
- Gobburu JV, et al. "Pharmacokinetic-pharmacodynamic modeling of ipamorelin." J Clin Pharmacol. 1999.