Peptides & growth hormone

MOD-GRF (1-29)

Updated · 21 sources · Editorial policy

MOD-GRF (1-29), short for “modified growth hormone-releasing factor (1-29),” is a synthetic peptide made from the first 29 amino acids of growth hormone-releasing hormone (GHRH), the hypothalamic hormone that signals the pituitary gland to release growth hormone (GH). Four of those 29 amino acids are swapped for others to make the peptide more stable. It is the same molecule usually sold as CJC-1295 no DAC, and a 2026 clinical review lists the names together as one compound: “CJC-1295 (without DAC) (Mod GRF 1–29/Mod GHRH 1-29)” (Dominikowski et al., Front Endocrinol 2026).

The library keeps a separate page for each name because both are widely used. This page explains what each part of the name means, why each of the four amino acid changes was made, and how the peptide relates to CJC-1295 with DAC, sermorelin and tesamorelin.

The single most important fact: no peer-reviewed human study of this peptide has been published. The same 2026 review placed it in its lowest evidence tier, with no published route of administration, human half-life, efficacy or safety data, and it has never been approved as a medicine by FDA or EMA.

This page summarizes what the peptide chemistry, doping-control and regulatory literature reports. It is for education only and is not medical advice.

Property Detail
Class Synthetic GHRH analog (growth hormone-releasing factor)
Other names CJC-1295 no DAC, CJC-1295 without DAC, modified GRF 1-29, Mod GHRH 1-29
Structure The 29-amino-acid GHRH fragment with four substitutions, amidated at the end; no albumin-binding group
Mechanism Acts on the GHRH receptor of the pituitary, which releases GH; IGF-I rises downstream
Human trials None published
Half-life Not measured in humans; the unmodified fragment lasts about 10–20 minutes in human plasma
Approval status Never approved by FDA or EMA
US status Not a controlled substance; FDA listed CJC-1295 among compounding substances that may present significant safety risks (nomination later withdrawn)
WADA status Prohibited at all times under S2.2.4, GHRH and its analogues

What it is

Decoding the name

  • GRF is the older name for GHRH. The hormone was discovered in 1982 and was long called growth hormone-releasing factor in the research literature (Campbell et al., Biopolymers 1995).
  • (1-29) refers to amino acids 1 through 29. Natural human GHRH is 44 amino acids long, but the fragment made of its first 29 keeps the hormone’s activity; that fragment, unchanged, is sermorelin (Esposito et al., Adv Drug Deliv Rev 2003).
  • Modified means four of those 29 amino acids have been replaced. Doping-control chemists describe the peptide as GRF(1-29) amide carrying D-alanine at position 2, glutamine at position 8, alanine at position 15 and leucine at position 27 (Knoop et al., Anal Bioanal Chem 2016).

Why each of the four changes was made

Natural GHRH breaks down in two different ways: an enzyme in the blood cuts it, and in water some of its amino acids slowly change chemically. Hoffmann-La Roche researchers described these weak points in the early 1990s (Campbell et al., Peptides 1994), and each substitution in MOD-GRF (1-29) addresses one of them:

  • Position 2, enzyme protection. The plasma enzyme dipeptidyl peptidase IV (DPP-IV) cuts GHRH between its second and third amino acids (Campbell et al., 1994). The shortened product has less than a thousandth of the original activity (Frohman et al., J Clin Invest 1986). Swapping the natural alanine at position 2 for its mirror-image form, D-alanine, blocks this cut. In 10 healthy men, that single change roughly halved metabolic clearance of GHRH(1-29), from 39.7 to 21 mL/kg/min (Soule et al., JCEM 1994).
  • Position 8, chemical stability. The natural asparagine at position 8 rearranges into other forms in water, which greatly reduces activity. Replacing it with glutamine, a choice the authors describe as not naturally occurring, slowed this rearrangement in laboratory tests (Campbell et al., 1994).
  • Position 15, receptor binding. Replacing the natural glycine with alanine had already been shown to strengthen binding to the GHRH receptor (Campbell et al., 1994). Roche chemists described the single-substitution version of GRF(1-29) as a “superactive” analog (Bongers et al., Pept Res 1992).
  • Position 27, oxidation. The natural methionine at position 27 oxidizes in water, reducing activity. Leucine does not (Campbell et al., 1994).

Three of these changes (positions 8, 15 and 27) match Roche’s experimental analogs, which protected the start of the chain differently. In that study they were tested in rat pituitary cells and in pigs, not in people, so their results do not describe MOD-GRF (1-29) (Campbell et al., 1994).

What the substitutions do not do is make the peptide long-acting. A peptide this small is still filtered out by the kidneys within minutes (Esposito et al., 2003). That is why ConjuChem, the Montreal company behind CJC-1295, added an albumin-binding group to this same four-substitution backbone to create its long-acting drug (Jetté et al., Endocrinology 2005).

One backbone, several names

Peptide Change from GHRH(1-29) Human data Status
Sermorelin None; the natural fragment Approved-drug data FDA-approved as Geref (NDA 020443); discontinued
CJC-1293 D-alanine at position 2 only Clearance study of the D-Ala2 analog in 10 men Never approved; named on the WADA list
MOD-GRF (1-29), also sold as CJC-1295 no DAC Four substitutions None published Never approved
CJC-1295 with DAC The same four substitutions plus an added lysine carrying an albumin-binding group Early-phase studies in healthy adults; estimated half-life 5.8–8.1 days Never approved
Tesamorelin Full 44-amino-acid GHRH with a hexenoyl group at the start of the chain Randomized trials FDA-approved as Egrifta (2010)

Sources for the table: Knoop et al., 2016; Soule et al., 1994; Jetté et al., 2005; Teichman et al., JCEM 2006; Dominikowski et al., 2026; Drugs@FDA, Geref; Drugs@FDA, Egrifta.

The labels are not used consistently. In the 2005 paper that introduced it, “CJC-1295” meant the albumin-binding conjugate (Jetté et al., 2005). Since then, anti-doping laboratories have used “CJC-1295” for the plain four-substitution peptide (Knoop et al., 2016), and Danish forensic chemists reported seized powders as “modified GRF 1-29” (Gajda et al., Drug Test Anal 2019). In practice, “Mod GRF 1-29” and “CJC-1295 no DAC” point to the same molecule, while “CJC-1295” on its own can mean either version. The CJC-1295 no DAC page traces this naming history in more detail.

How it works in the body

Like natural GHRH, the peptide is designed to act on GHRH receptors on the pituitary cells that make GH. The 2026 review describes its expected effect as a short-lived rise in GH released in the body’s own pulses, followed by higher IGF-I (insulin-like growth factor I, the hormone GH drives the liver to make), but notes that this is inferred from studies of unmodified GRF(1-29), not measured with this peptide (Dominikowski et al., 2026).

No human pharmacokinetic study exists. The closest available evidence comes from related peptides and from animal and laboratory work:

Evidence Finding Setting
Unmodified GRF(1-29) (sermorelin) Plasma half-life about 10–20 minutes, from kidney filtration and enzyme cleavage Humans (Esposito et al., 2003)
GRF(1-29) with D-alanine at position 2 only Clearance 21 vs 39.7 mL/kg/min; disappearance half-time 6.7 vs 4.3 minutes 10 healthy men, infusion (Soule et al., 1994)
MOD-GRF (1-29), 0.1 mg intravenous Intact peptide still detected at 8 hours, the last sample; sermorelin detected only at 2 hours Rats; detection only, no pharmacokinetic analysis (Knoop et al., 2016)

The rat results show that the peptide resists breakdown better than sermorelin, but the authors stressed that they reported detection only, not a half-life.

Regulatory and anti-doping status

  • Not an approved drug. Neither CJC-1295 variant is approved by FDA or EMA (Dominikowski et al., 2026).
  • Flagged by FDA for compounding. FDA’s list of bulk substances that “may present significant safety risks” includes CJC-1295, without naming a variant. FDA cited immunogenicity risk (antibody formation) by certain routes, complexities with peptide-related impurities and characterization of the active ingredient, limited clinical data, and serious adverse events including increased heart rate and a systemic vasodilatory reaction (widening of blood vessels throughout the body). The nominator later withdrew the nomination, so CJC-1295 now appears in FDA’s table of withdrawn nominations (FDA bulk drug substances, category 2).
  • Not a controlled substance in the US. The DEA’s anabolic steroid schedule does not name GHRH analogs (21 CFR 1308.13).
  • Banned in sport. The WADA 2026 Prohibited List bans growth hormone releasing factors at all times under S2.2.4, naming GHRH and its analogues “including, but not limited to” CJC-1293, CJC-1295, sermorelin and tesamorelin. A different market name does not take a GHRH analog outside the ban.

Laboratories can detect it. Because the position-2 change blocks the cut that breaks down sermorelin, the intact peptide stays in samples longer, and a validated plasma method identifies it at under 50 pg/mL (Knoop et al., 2016). Urine methods generally reach WADA’s 1 ng/mL required performance limit or lower (Memdouh et al., Drug Test Anal 2021; Uçaktürk and Nemutlu, J Pharm Biomed Anal 2026).

What the research shows

In humans

No human study of this peptide has been published. The 2026 review sorted GH-axis peptides into four evidence tiers, from randomized trials (tesamorelin) to no human studies at all. It placed CJC-1295 without DAC in the lowest tier and said claims about natural GH pulsing or body composition come mostly from extrapolation from GRF(1-29) and from non-academic sources. It concluded that there is “no peer-reviewed support” for meaningful effects on body composition or performance (Dominikowski et al., 2026).

  • The D-alanine study tested one of the four substitutions, as a constant infusion, and measured only clearance (Soule et al., 1994). It did not test the four-substitution peptide or any health outcome.
  • The Roche analogs shared three of the four substitutions and were 11 to 13 times more potent than natural GHRH when injected under the skin in pigs (Campbell et al., 1994). They were different molecules tested in animals.
  • The DAC trials tested the albumin-bound conjugate. In healthy adults, one injection raised mean GH 2- to 10-fold for 6 days or more, with an estimated half-life of 5.8–8.1 days (Teichman et al., 2006). That long action comes from albumin binding, which MOD-GRF (1-29) lacks, so these results cannot be transferred to it. The CJC-1295 with DAC page covers those trials.

On “Mod GRF gives natural GH pulses.” This is the main claim made for the peptide: that a short-acting GHRH analog preserves the body’s GH pulses better than a long-acting one. No human study has measured GH pulsing after MOD-GRF (1-29). The only human pulsatility study of a CJC-1295 compound used the long-acting DAC version and found pulse frequency and size unchanged, with the extra GH coming mainly from higher levels between pulses (Ionescu and Frohman, JCEM 2006).

Side effects and risks

No human safety record

With no published human study, there is no systematic record of adverse effects, no dose shown to be safe, and no information on repeated or long-term use (Dominikowski et al., 2026). The serious adverse events FDA identified with CJC-1295 (increased heart rate and a systemic vasodilatory reaction) are the only regulator-reported safety signal, and FDA did not say which variant was involved (FDA bulk drug substances, category 2).

Risks shared by GHRH analogs

  • Raised GH and IGF-I. The review flags GH/IGF-I growth signaling as a theoretical cancer concern across these peptides, while noting there is no established clinical cancer signal (Dominikowski et al., 2026).
  • Blood sugar. GH counteracts insulin. In a trial of a different long-acting GHRH (bonded to polyethylene glycol), repeated dosing in elderly volunteers caused some impairment of glucose tolerance, and injection-site reactions were more frequent than with placebo (Munafo et al., Eur J Endocrinol 2005).
  • Antibodies. Immune reactions to injected peptides are a recognized risk and one of the reasons FDA gave for flagging CJC-1295.

What is actually in the vial

Products sold under these names are made outside pharmaceutical regulation, and the label does not guarantee the contents:

  • In Danish customs seizures, powders identified as modified GRF 1-29 and other GH-releasing peptides all carried an extra glycine amino acid at the start of the chain compared with reference standards (Gajda et al., 2019).
  • A preparation seized in Norway in 2009 contained a 29-amino-acid amidated peptide matching the product sold as CJC-1295, showing that a “CJC-1295” label can mean the non-DAC peptide (Henninge et al., Drug Test Anal 2010).

Key takeaways

  • Same molecule as CJC-1295 no DAC. “MOD-GRF (1-29)” means GHRH’s first 29 amino acids with four substitutions; it is the four-substitution backbone of CJC-1295 without the albumin-binding group.
  • Each substitution fixes a known weak point. The changes block enzyme cleavage (position 2), slow chemical breakdown (positions 8 and 27) and strengthen receptor binding (position 15).
  • Stable, but not long-acting. The changes protect the peptide from breakdown, but nothing extends its stay in the body the way albumin binding does for the DAC version. Its human half-life has never been measured.
  • No human evidence. No peer-reviewed human study exists, and claims about GH pulses or body composition are extrapolated from related peptides.
  • Flagged and banned. FDA lists CJC-1295 as a compounding safety risk, citing increased heart rate and a systemic vasodilatory reaction, and WADA prohibits it at all times under S2.2.4.

Sources

  1. Dominikowski A, Rękoś Z, Olejarz M, Szczepanek-Parulska E, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475. PubMed; PMC.
  2. Campbell RM, Bongers J, Felix AM. Rational design, synthesis, and biological evaluation of novel growth hormone releasing factor analogues. Biopolymers. 1995;37(2):67–88. PubMed.
  3. Campbell RM, Stricker P, Miller R, Bongers J, et al. Enhanced stability and potency of novel growth hormone-releasing factor (GRF) analogues derived from rodent and human GRF sequences. Peptides. 1994;15(3):489–495. PubMed.
  4. Bongers J, Felix AM, Campbell RM, Lee Y, Merkler DJ, Heimer EP. Semisynthesis of human growth hormone-releasing factors by alpha-amidating enzyme catalyzed oxidation of glycine-extended precursors. Pept Res. 1992;5(4):183–189. PubMed.
  5. Knoop A, Thomas A, Fichant E, Delahaut P, et al. Qualitative identification of growth hormone-releasing hormones in human plasma by means of immunoaffinity purification and LC-HRMS/MS. Anal Bioanal Chem. 2016;408(12):3145–3153. PubMed; PMC.
  6. Frohman LA, Downs TR, Williams TC, Heimer EP, et al. Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive product cleaved at the NH2 terminus. J Clin Invest. 1986;78(4):906–913. PubMed.
  7. Soule S, King JA, Millar RP. Incorporation of D-Ala2 in growth hormone-releasing hormone-(1-29)-NH2 increases the half-life and decreases metabolic clearance in normal men. J Clin Endocrinol Metab. 1994;79(4):1208–1211. PubMed.
  8. Esposito P, Barbero L, Caccia P, et al. PEGylation of growth hormone-releasing hormone (GRF) analogues. Adv Drug Deliv Rev. 2003;55(10):1279–1291. PubMed.
  9. Jetté L, Léger R, Thibaudeau K, et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005;146(7):3052–3058. PubMed.
  10. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799–805. PubMed.
  11. Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792–4797. PubMed.
  12. Munafo A, Nguyen TX, Papasouliotis O, Lécuelle H, Priestley A, Thorner MO. Polyethylene glycol-conjugated growth hormone-releasing hormone is long acting and stimulates GH in healthy young and elderly subjects. Eur J Endocrinol. 2005;153(2):249–256. PubMed.
  13. Gajda PM, Holm NB, Hoej LJ, Rasmussen BS, et al. Glycine-modified growth hormone secretagogues identified in seized doping material. Drug Test Anal. 2019;11(2):350–354. PubMed.
  14. Henninge J, Pepaj M, Hullstein I, Hemmersbach P. Identification of CJC-1295, a growth-hormone-releasing peptide, in an unknown pharmaceutical preparation. Drug Test Anal. 2010;2(11–12):647–650. PubMed.
  15. Memdouh S, Gavrilović I, Ng K, Cowan D, Abbate V. Advances in the detection of growth hormone releasing hormone synthetic analogs. Drug Test Anal. 2021;13(11–12):1871–1887. PubMed.
  16. Uçaktürk E, Nemutlu E. Analysis of growth hormone releasing hormone and its analogs in urine using nano liquid chromatography coupled with quadrupole/orbitrap mass spectrometry. J Pharm Biomed Anal. 2026;268:117207. PubMed.
  17. Food and Drug Administration. Certain bulk drug substances for use in compounding may present significant safety risks (category 2 under the interim policies). FDA.
  18. Food and Drug Administration. Drugs@FDA: Geref (sermorelin acetate), NDA 020443, discontinued. Drugs@FDA.
  19. Food and Drug Administration. Drugs@FDA: Egrifta (tesamorelin), BLA 022505, approved November 10, 2010. Drugs@FDA.
  20. World Anti-Doping Agency. 2026 Prohibited List, section S2.2.4 (growth hormone releasing factors), in effect 1 January 2026. WADA 2026 Prohibited List.
  21. Drug Enforcement Administration. Schedule III controlled substances, 21 CFR 1308.13. 21 CFR 1308.13.