Modified GRF (1-29), CJC-1295 without DAC
MOD-GRF
Cited range Altered GRF analog
What it is
MOD-GRF, also written as Modified GRF (1-29) or CJC-1295 without DAC, is a synthetic GHRH analog with four amino-acid substitutions that resist enzymatic degradation. The "without DAC" qualifier means it lacks the drug-affinity complex that gives CJC-1295 with DAC a week-long half-life. It is therefore the short-acting member of that pair.
Benefits in plain language
What researchers and reference users usually mean when they talk about this compound. These are study themes and common claims — not a promise that it will do this in you.
- This is the short-acting version of the growth-hormone-releasing signal — a pulse, not a slow drip.
- It mimics GHRH, the hormone your hypothalamus uses to tell the pituitary to release growth hormone.
- Because it acts upstream, it can be stacked with a ghrelin-pathway peptide like ipamorelin for a bigger pulse.
- It only works when your own pituitary is still capable of responding.
If a branded, FDA-approved product exists, that label is the only dose that is actually authorized. Research-chemical vials are a different object.
Mechanism of action
MOD-GRF binds GHRH receptors on anterior pituitary somatotrophs, raising cAMP and driving GH synthesis and release. It preserves the natural pulsatile pattern rather than producing continuous elevation. The substitutions slow DPP-4 cleavage, lengthening action from minutes to a few hours. Its effect is gated by somatostatin tone and by IGF-1 negative feedback.
Possible side effects / caveats
Class effects include water retention, joint discomfort, tingling, and possible increases in fasting glucose or IGF-1. Chronic GH elevation raises concerns about insulin resistance and tissue growth if sustained. Because it depends on pituitary reserve, effects vary widely and are minimal in older or hypopituitary users.
Protocol ranges
| Source tier | Amount | Frequency / duration | Notes |
|---|---|---|---|
| Cited range | 100–200 mcg per dose | 1–3× daily, often pre-sleep or post-training | Usually paired with a GHRP |
| Cited range | Cycled 8–12 weeks | Followed by a break | Not a validated clinical schedule |