Head-to-head comparison
| Property | MK-677 | CJC-1295 |
|---|---|---|
| Category | Muscle & Growth | Muscle & Growth |
| Legal Status | Unregulated | Reclassification Pending |
| Primary Route | oral | subcutaneous |
| Half-life | ~24 hours | ~30 minutes (no DAC) / ~8 days (with DAC) |
| Mol. Weight | 528.67 Da | 3,367.97 Da |
| Side Effects | Increased appetite / intense hunger, Water retention and edema, Insulin resistance (glucose elevation) | Flushing, Headache, Dizziness |
Key differences
- Receptor pathway: MK-677 acts on ghrelin receptors (GHS-R); CJC-1295 acts on GHRH receptors. These are complementary, not redundant, pathways.
- Administration: MK-677 is oral (pill/capsule, once daily); CJC-1295 with DAC is injectable (subcutaneous, 1–2 times weekly).
- GH pattern: MK-677 produces sustained 24-hour GH/IGF-1 elevation; CJC-1295 with DAC also produces sustained elevation. CJC-1295 without DAC produces more pulsatile release.
- Appetite: MK-677 significantly increases appetite; CJC-1295 has minimal appetite effects.
- Metabolic effects: MK-677 can raise fasting glucose and reduce insulin sensitivity; CJC-1295 has fewer metabolic side effects.
- Synergy potential: Because they act on different receptor pathways, MK-677 and CJC-1295 are commonly discussed as a combination for maximizing GH output.
- Clinical data: MK-677 has published human clinical trials; CJC-1295 has limited published clinical data.
The verdict
MK-677 offers oral convenience and published clinical data, while CJC-1295 provides GH stimulation through a complementary pathway with fewer metabolic side effects. Rather than choosing one over the other, many GH optimization protocols combine a ghrelin-pathway compound with a GHRH-pathway compound for synergistic effects. As standalone options, MK-677 is more convenient (oral, no injections) while CJC-1295 has a cleaner metabolic profile (no appetite increase, no glucose effects).
Frequently asked questions
Yes, they are commonly discussed as a combination because they act on different receptor pathways (ghrelin vs GHRH). Combining a ghrelin-pathway compound with a GHRH-pathway compound is a standard approach for maximizing synergistic GH release. However, this increases the total GH stimulus and associated risks.
Both can significantly raise GH and IGF-1 levels. MK-677 has more published human data showing up to 40% IGF-1 increases. CJC-1295 with DAC produces sustained GH elevation. Direct comparison is difficult due to different measurement protocols in published studies.
No, MK-677 is a non-peptide small molecule that mimics ghrelin's action on the GHS-R receptor. CJC-1295 is a true peptide (a modified GHRH analog). MK-677's non-peptide nature is what gives it oral bioavailability.
CJC-1295 generally has a cleaner side effect profile — no significant appetite increase, no glucose effects. MK-677 causes increased appetite, potential water retention, and can impair insulin sensitivity. Both share GH-related side effects like joint pain and paresthesias at high GH levels.
No, MK-677 is orally active and taken as a pill or capsule. This is its primary convenience advantage over CJC-1295 and other injectable GH-releasing peptides. No refrigeration or injection supplies are needed.