Modified GRF (1-29)
A tetra-substituted GHRH(1-29) analogue (often called mod GRF 1-29 or CJC-1295 without DAC) widely used in the research-peptide community with GHRPs to stimulate pulsatile GH release. Human data are limited to the parent GHRH analogue class.
01 Overview
Modified GRF (1-29) is a synthetic analogue of the first 29 amino acids of growth-hormone-releasing hormone with four amino-acid substitutions that increase stability against enzymatic degradation. It is functionally the non-DAC version of CJC-1295, giving a short-lived GHRH signal that synergises with ghrelin-receptor agonists (GHRPs).
Unlike the approved GHRH analogues sermorelin and tesamorelin, mod GRF 1-29 itself is not an approved drug and its use is essentially research/anecdotal. Evidence for its acute GH-releasing action derives from the broader GHRH(1-29) literature; chronic outcome data in humans are absent.
02 Mechanism
Binds the pituitary GHRH receptor to stimulate GH synthesis and pulsatile release; substitutions slow degradation for a modestly longer signal than native GHRH.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Anecdotal (research) | 100 mcg | SubQ | Commonly self-reported dose, often paired with a GHRP; not a validated protocol. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Acute GH pulseStimulates a short pulse of endogenous GH via the GHRH receptor. | transient rise | Preclinical | |
| Synergy with GHRPsAnecdotally combined with ghrelin agonists for a larger combined GH pulse. | reported additive GH release | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Injection-site reactionsLocal redness or itching at the injection site. | Mild | Common | Anecdotal | |
| Water retention/tinglingGH-class fluid retention or paraesthesia at higher combined dosing. | Mild | Uncommon | Anecdotal |