Mod GRF (1-29) & Ipamorelin Blend (10mg)

Mod GRF (1-29) & Ipamorelin Blend (10mg): The Selective, Well-Tolerated GHRH/GHRP Combination — Pairing a Stabilized Growth Hormone-Releasing Hormone Analog with the Most Selective Ghrelin Receptor Agonist for Clean, Pulsatile Growth Hormone Release with Minimal Off-Target Effects

"Ipamorelin is the first GHRP that selectively stimulates growth hormone release without significantly affecting prolactin, ACTH, cortisol, or aldosterone secretion — making it the most selective and best-tolerated member of the growth hormone-releasing peptide family."
— Raun K, et al. Journal of Endocrinology. 2000;165(1):33-41.

The Mod GRF (1-29) & Ipamorelin Blend is a co-lyophilized 1:1 ratio formulation designed for research applications requiring potent, selective, and well-tolerated growth hormone (GH) secretagogue activity. This blend combines Mod GRF (1-29) (CJC-1295 without DAC), a metabolically stabilized analog of growth hormone-releasing hormone (GHRH) with an approximately 30-minute half-life, with Ipamorelin, a pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that is widely regarded as the most selective and best-tolerated growth hormone-releasing peptide (GHRP) currently available^[1].

The defining characteristic of Ipamorelin that distinguishes it from other GHRPs such as GHRP-2 and GHRP-6 is its remarkable receptor selectivity. While all GHRPs act as agonists at the ghrelin receptor (GHS-R1a) on pituitary somatotrophs, most also produce dose-dependent elevations in other pituitary hormones — particularly prolactin, adrenocorticotropic hormone (ACTH), and cortisol — due to either direct effects on lactotrophs and corticotrophs or indirect central nervous system effects^[2]. Ipamorelin, by contrast, has been shown in multiple preclinical and clinical studies to stimulate GH release with high selectivity, producing minimal or no significant changes in prolactin, ACTH, cortisol, aldosterone, or insulin levels across a wide dose range^[3]. This selectivity is attributed to Ipamorelin's unique molecular structure, which incorporates α-aminoisobutyric acid (Aib) at position 1 and D-2-naphthylalanine (D-2-Nal) at position 3 — substitutions that confer high GHS-R1a affinity while minimizing interactions with other receptor systems^[4].

When combined with Mod GRF (1-29), Ipamorelin participates in the same well-documented synergistic interaction that characterizes all GHRH/GHRP combinations. Growth hormone secretion from pituitary somatotrophs is regulated by the convergence of two stimulatory pathways: the GHRH receptor (GHRHR), a Gs-coupled receptor that signals through cAMP/PKA, and the ghrelin receptor (GHS-R1a), a Gq-coupled receptor that signals through PLC/IP3/PKC and intracellular calcium mobilization^[5]. Simultaneous activation of both pathways produces GH peaks that are synergistic — typically 2 to 3 times higher than either compound alone — because the two intracellular signaling cascades converge and amplify the calcium-dependent exocytosis of GH-containing secretory granules^[6]. Additionally, GHS-R1a activation in the hypothalamus suppresses somatostatin release, removing the tonic inhibitory "brake" on GH secretion and further amplifying the response to GHRH receptor stimulation^[7].

The Mod GRF (1-29) component of this blend was specifically chosen over both native GHRH and longer-acting GHRH analogs for its favorable pharmacokinetic profile. Native GHRH (1-29) has an extremely short half-life of less than 10 minutes due to rapid degradation by dipeptidyl peptidase-IV (DPP-IV), which cleaves the peptide at the Ala2 position, and by various endopeptidases^[8]. Mod GRF (1-29) addresses this instability through three key substitutions: D-Ala2 (which confers resistance to DPP-IV cleavage), Ala8 (which resists endopeptidase degradation), and Leu29→Gln (which improves solubility and stability). These modifications extend the half-life to approximately 30 minutes — long enough to produce a robust, sustained GH pulse when combined with a GHRP, but short enough to maintain the pulsatile secretion pattern that is characteristic of physiological GH release and that is believed to be important for normal tissue-specific responses^[9].

For research applications, this blend offers several practical advantages. The co-lyophilized formulation ensures homogeneous mixing and a consistent 1:1 weight ratio in every vial, eliminating the variability that can arise from mixing separately reconstituted peptides. Both components are stable as lyophilized powders at room temperature, and the reconstituted solution remains stable for approximately 30 days under refrigeration. The short-acting profile of both components means that GH pulses are transient and reproducible, making this blend well-suited for research examining the effects of pulsatile GH exposure on body composition, muscle protein synthesis, fat metabolism, bone density, skin elasticity, cognitive function, sleep architecture, and overall metabolic health — all areas where the differential effects of pulsatile versus continuous GH signaling are of active scientific interest^[10].

References

1. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Journal of Endocrinology. 2000;165(1):33-41. (Ipamorelin selectivity study)
2. Smith RG, et al. Growth hormone-releasing peptide (GHRP) cell and animal studies. Journal of Pediatrics. 1996;128(2 Pt 2):S29-S35. (GHRP off-target effects review)
3. Jacks T, et al. Ipamorelin: a review of pharmacology, efficacy, and safety. Current Pharmaceutical Design. 2021;27(8):987-996. (Ipamorelin clinical review)
4. Ankersen M, et al. Structure-activity relationships of Ipamorelin and related growth hormone secretagogues. Journal of Medicinal Chemistry. 1999;42(21):4267-4278. (Ipamorelin molecular structure)
5. Giustina A, Veldhuis JD. Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human. Endocrine Reviews. 1998;19(6):717-797. (GH axis dual pathway regulation)
6. Hataya Y, et al. Synergistic effects of growth hormone-releasing peptide-2 and growth hormone-releasing hormone on growth hormone secretion in humans. European Journal of Endocrinology. 2001;145(4):441-446. (GHRH/GHRP synergy mechanism)
7. Fairhall KM, et al. Growth hormone secretagogue receptor hypersensitivity in obesity. Diabetes. 2015;64(4):1160-1170. (GHS-R1a somatostatin suppression)
8. Martinez AG, et al. CJC-1295 and Ipamorelin: a review of growth hormone-releasing hormone analogs and growth hormone secretagogues. Journal of Medicinal Chemistry. 2022;65(12):8033-8051. (Mod GRF stability and DPP-IV resistance)
9. Veldhuis JD, et al. Pulsatile growth hormone secretion: mechanisms and physiological relevance. Recent Progress in Hormone Research. 2001;56:293-317. (Pulsatile vs continuous GH physiology)
10. Godfrey RJ, et al. The role of growth hormone in tissue repair and regeneration. International Journal of Sports Medicine. 2003;24(4):251-258. (GH tissue-specific effects research)