A stabilized GHRH fragment with 4 amino acid substitutions — the preferred 'clean' pulsatile GH secretagogue.
MOD-GRF (1-29), also known as CJC-1295 without DAC or tetrasubstituted GRF (1-29), is a synthetic analog of the first 29 amino acids of GHRH with four amino acid substitutions at positions 2 (D-Ala), 8 (Gln), 15 (Ala), and 27 (Leu). These modifications protect the peptide from enzymatic degradation, extending its half-life from ~7 minutes (native GHRH 1-29) to approximately 30 minutes.
The 30-minute half-life is intentionally short compared to CJC-1295 with DAC (6-8 days). This shorter duration produces physiologically natural GH pulses rather than the sustained GH elevation caused by DAC-conjugated versions. Many clinicians prefer MOD-GRF specifically because it mimics the body's natural pulsatile GH secretion pattern.
MOD-GRF is almost always combined with a GHRP (typically ipamorelin) for synergistic GH release. The GHRH analog amplifies the magnitude of the GH pulse while the GHRP triggers the release timing — together producing a robust, physiological GH pulse.
Research demonstrates the four amino acid substitutions increase potency and stability while maintaining the same receptor binding and GH stimulation as native GHRH (1-29). Combined with ipamorelin, MOD-GRF produces synergistic GH release approximately 3-5x greater than either agent alone.
The pulsatile GH release pattern produced by MOD-GRF is associated with better receptor sensitivity maintenance versus continuous GH elevation. This may reduce the risk of desensitization seen with longer-acting agents.
📚 Key Reference: PMID: 16882916 (GRF analog studies)
Well-tolerated. Injection site reactions, headache, flushing may occur. IGF-1 monitoring is essential. Avoid in active malignancy. Consult your provider.
NOT FDA-approved. Available through compounding pharmacies. WADA prohibited.