Ipamorelin vs MK-677
Side-by-Side Comparison
| Attribute | Ipamorelin | Mk 677 |
|---|---|---|
| Category | Growth Hormone Secretagogue | Growth Hormone Secretagogue |
| Mechanism | Ipamorelin (sequence: Aib-His-D-2Nal-D-Phe-Lys-NH2) selectively binds to the Growth Hormone Secretagogue Receptor (GHS-R1a) on anterior pituitary somatotroph cells, increasing cAMP and activating... | MK-677 binds to the ghrelin receptor (GHS-R1a) in the pituitary gland and hypothalamus, mimicking the hunger hormone ghrelin. |
| Evidence Rating | D — Preclinical | C — Phase I–II Clinical Trials |
| Clinical Status | Research-only / Not approved for human use | Multiple Phase II trials completed. Not FDA-approved. Investigational. |
| Safety Profile | Widely regarded as the mildest GHS available; minimal side effects in published animal and human studies; Common: injection site reactions (redness, swelling, bruising) in 15-30% of users, resolving within 24-48 hours | Common: increased appetite (ghrelin agonism), water retention/mild edema, transient muscle pain; Metabolic: may elevate fasting blood glucose and reduce insulin sensitivity (dose-dependent); important for diabetics and pre-diabetics |
| Route | Subcutaneous | Oral (capsule or liquid) |
| Dose Range | 100–300 mcg per injection, 2–3x daily | 10–25 mg/day orally |
| Frequency | 2–3 times daily (typically before meals and before bed) | Once daily |
| Molecular Weight | ~711.9 g/mol | ~528.7 g/mol (624.8 as mesylate salt) |
| Half-Life | ~2 hours | ~4–6 hours (plasma); functional activity ~24 hours |
Overview
Ipamorelin and MK-677 are both research peptides studied across multiple applications. This comparison examines their mechanisms, evidence base, dosing protocols, and safety profiles to help researchers understand the key differences and overlaps.
Ipamorelin — Mechanism & Evidence
Ipamorelin is the most selective growth hormone secretagogue (GHS) available, a synthetic pentapeptide (MW ~711.86 g/mol, formula C38H49N9O5) that stimulates pulsatile GH release from the pituitary gland without significantly affecting cortisol, prolactin, or appetite. It is widely regarded as the mildest GHS, making it popular in anti-aging, body composition, and recovery contexts. However, research on ipamorelin is limited, and it is not FDA-approved for any indication.
Key claims: Increases growth hormone levels; Improves body composition; Improves sleep quality.
MK-677 — Mechanism & Evidence
MK-677 (Ibutamoren) is a potent, long-acting, orally-active, non-peptide ghrelin receptor (GHS-R1a) agonist that stimulates growth hormone release without injections. Unlike injectable GH peptides such as GHRP-6 or Ipamorelin, MK-677 can be taken orally and maintains elevated GH and IGF-1 levels for up to 24 hours. It has been studied in several human clinical trials for GH deficiency, muscle wasting, bone density, and sleep quality, but is not FDA-approved for any indication.
Key claims: Increases growth hormone and IGF-1 levels; Improves sleep quality; Increases lean body mass.
Shared Research Applications
Both peptides are studied for: Anti-Aging, Body Composition, Sleep.
Ipamorelin is also researched for: no additional unique applications.
MK-677 is also researched for: no additional unique applications.
Safety Considerations
Ipamorelin: Widely regarded as the mildest GHS available; minimal side effects in published animal and human studies Common: injection site reactions (redness, swelling, bruising) in 15-30% of users, resolving within 24-48 hours Common: mild temporary "head rush" or flushing immediately after injection due to sudden vasodilation
MK-677: Common: increased appetite (ghrelin agonism), water retention/mild edema, transient muscle pain Metabolic: may elevate fasting blood glucose and reduce insulin sensitivity (dose-dependent); important for diabetics and pre-diabetics Fatigue and lethargy reported by some users
Related Products
Related Research News
CJC-1295 with DAC and Ipamorelin: Growth Hormone Research Guide
CJC-1295 with DAC and Ipamorelin represent key compounds in growth hormone research, targeting distinct pathways for GH and IGF-1 signaling. CJC-1295 with DAC acts as a long-acting GHRH analogue with a half-life of 5.8 to 8.1 days, while Ipamorelin functions as a selective growth hormone secretagogue via the ghrelin receptor. Together, they support studies on metabolism, recovery, and body composition.
Ipamorelin vs GHRP-2: Which Offers More Targeted GH Release?
Ipamorelin and GHRP-2 both stimulate growth hormone release via the ghrelin receptor, but Ipamorelin provides more selective action with minimal impact on other hormones like ACTH and cortisol. GHRP-2 delivers stronger GH pulses alongside broader endocrine effects. Combining them can enhance overall GH output through additive receptor stimulation.
Ipamorelin: Selective GH Secretagogue for Clean Pulsatile Release
Ipamorelin, a third-generation GHS-R1a agonist (CAS 170851-70-4), stimulates pulsatile growth hormone release without elevating cortisol or prolactin, unlike earlier GHRPs. This selectivity supports precise research into GH axis effects, IGF-1 pathways, body composition, recovery, and sleep. Studies highlight its role in anabolic processes and synergy with CJC-1295 for enhanced GH output.