What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide that acts as a selective growth hormone secretagogue (GHRP-5). It was developed by Novo Nordisk in the 1990s as an alternative to first-generation GHRPs (GHRP-2, GHRP-6) with an improved selectivity profile.
Its mechanism of action involves binding to the ghrelin receptor (GHSR-1a) in the anterior pituitary, stimulating pulsatile growth hormone release — mimicking the natural physiological pattern.
Why ipamorelin stands out among GHRPs
Selectivity is its main competitive advantage over other secretagogues:
| GHRP | Elevates GH | Elevates Cortisol | Elevates Prolactin | Elevates ACTH |
|---|---|---|---|---|
| GHRP-6 | ✅ | ✅✅ | ✅✅ | ✅ |
| GHRP-2 | ✅✅ | ✅ | ✅ | ✅ |
| Ipamorelin | ✅✅ | ❌ | ❌ | ❌ |
Ipamorelin produces GH release comparable to GHRP-2 without the side effects related to cortisol and prolactin, making it more suitable for long-term protocols.
Research applications
Preclinical models and reported research use explore ipamorelin for:
- Body composition: Increased lean mass, reduced body fat via GH.
- Recovery: Greater hepatic IGF-1 synthesis, which mediates the anabolic effects of GH.
- Anti-aging: Restoration of GH pulses that decline with age (somatopause).
- Sleep and recovery: GH is primarily released during deep sleep; ipamorelin potentiates this pulse when administered at bedtime.
- Bone density: GH and IGF-1 have documented effects on bone mineralization.
Combination with CJC-1295
Ipamorelin is frequently used in combination with CJC-1295 No DAC (GHRH). The rationale:
- CJC-1295 acts on the GHRH receptor, increasing the amount of GH available for release.
- Ipamorelin acts on GHSR-1a, stimulating the release pulse.
- Together they produce a synergistic, more sustained GH release than either alone.
Reconstitution (reference)
With 5 mg + 2.0 mL bacteriostatic water: 1 unit on a U-100 syringe ≈ 25 mcg.
Refrigerate at 2–8 °C once reconstituted. Do not shake; rotate gently.
Safety notes
Novo Nordisk clinical trials in the 1990s reported good tolerability. Reported adverse effects include: transient post-injection flushing, dizziness, mild tingling in hands/feet. No elevation of cortisol or prolactin reported at standard doses.
For research use only. Ipamorelin is not FDA approved for clinical use. Always consult a healthcare professional.
Reported protocol (research reference)
| Vial sizes | 5 mg, 10 mg |
|---|---|
| Reported dose | Literature reports 100–300 mcg per injection, 1–3 times per day (fasted or before sleep to potentiate the natural GH pulse). Reference values only. |
| Half-life | Approximately 2 hours. |
| FDA status | Not FDA approved |