Modified GRF 1-29 UK: CJC No DAC & UK Peptides
Modified GRF 1-29 UK Explained: The Peptide Behind CJC No DAC
Modified GRF 1-29 is a synthetic 29-amino-acid analogue of growth hormone-releasing hormone. It is commonly marketed as CJC-1295 without DAC, although the original scientific name CJC-1295 is more closely associated with a separate long-acting, albumin-binding compound.
What Is Modified GRF 1-29?
Modified GRF 1-29 is a laboratory-made analogue of the active 29-residue portion of human growth hormone-releasing hormone, usually shortened to GHRH.
Its sequence is based on GHRH(1–29), but four positions have been changed:
- Position 2 contains D-alanine.
- Position 8 contains glutamine.
- Position 15 contains alanine.
- Position 27 contains leucine.
The molecule is also amidated at its C-terminus.
PubChem records CJC-1295 without DAC with the formula C152H252N44O42 and a calculated molecular weight of approximately 3,368 g/mol. 1
In plain English: Modified GRF 1-29 resembles the first 29 amino acids of natural GHRH, but four carefully chosen building blocks have been replaced. It does not contain the albumin-binding DAC structure found in long-acting CJC-1295.
Tyr–D-Ala–Asp–Ala–Ile–Phe–Thr–Gln–Ser–Tyr–Arg–Lys–Val–Leu–Ala–Gln–Leu–Ser–Ala–Arg–Lys–Leu–Leu–Gln–Asp–Ile–Leu–Ser–Arg–NH₂
Why Were Four Amino Acids Changed?
The substitutions were intended to alter the way the peptide behaves when compared with unmodified GHRH(1–29).
D-Alanine
The natural alanine is replaced with its D-form. This position is important because the amino end of GHRH-related peptides is vulnerable to enzymatic breakdown.
Glutamine
Glutamine replaces the asparagine found at the equivalent position in native human GHRH(1–29).
Alanine
Alanine replaces glycine. The change forms part of the tetra-substituted peptide identity.
Leucine
Leucine replaces methionine, a residue that can be vulnerable to oxidation.
What Does Tetra-Substituted Mean?
“Tetra” means four. Tetra-substituted GRF(1–29) therefore describes a GRF-related 29-residue peptide with four substitutions.
The phrase is more informative than “no DAC” because it describes the peptide itself rather than only telling the reader which modification is absent.
“No DAC” tells you what the molecule lacks. Modified GRF 1-29 begins to tell you what the molecule actually is.
Why Is It Called CJC-1295 Without DAC?
The expression became common commercially, but it can obscure the history and structure of the two materials.
The original CJC-1295 development programme added an albumin-binding chemical group to a modified GHRH peptide. That complete long-acting molecule is now commonly called CJC-1295 with DAC. 2
The 29-residue peptide without the albumin-binding extension later became widely known online as:
- Modified GRF 1-29
- Mod GRF 1-29
- Tetra-substituted GRF 1-29
- CJC-1295 without DAC
- CJC-1295 no DAC
The FDA has documented inconsistent naming among CJC-1295-related substances and has noted that the same names have sometimes been attached to different structures or salt forms. 3
The Clearest Naming Approach
A useful description should state “Modified GRF 1-29” or “tetra-substituted GRF 1-29”, provide the complete sequence and say whether the material is a free base, acetate or another salt form.
Modified GRF 1-29 and CJC-1295 with DAC Compared
They share a related receptor-active peptide region but are not the same complete molecule.
| Feature | Modified GRF 1-29 | CJC-1295 with DAC |
|---|---|---|
| Common alternative name | CJC-1295 without DAC | CJC-1295 DAC or DAC:GRF |
| Peptide region | Modified GHRH-related sequence of 29 residues | Related peptide region plus an additional modified lysine |
| Drug Affinity Complex | Absent | Present |
| Albumin-binding design | No DAC-mediated covalent albumin attachment | Designed to form a covalent bond with circulating albumin |
| Recorded molecular formula | C152H252N44O42 | C165H269N47O46 for the PubChem CJC-1295 record |
| Human evidence | No direct human pharmacology programme was identified by the FDA for the free-base or acetate no-DAC forms | Small published human studies largely concern the long-acting DAC active moiety |
| Can evidence be transferred? | No. Findings involving the DAC-containing molecule should not be presented as direct evidence for Modified GRF 1-29. | |
Why This Is More Than a Duration Difference
It is tempting to describe the two materials simply as a short version and a long version. That explanation is incomplete.
The DAC-containing material has:
- An additional modified lysine;
- A maleimide-related reactive group;
- A different complete molecular mass;
- A different albumin interaction; and
- A separate human research history.
The two names therefore describe different active moieties rather than two strengths of one identical compound.
What Does the Evidence Show?
The evidence for the no-DAC material is considerably thinner than the broader online discussion might suggest.
The tetra-substituted 29-residue structure and its calculated molecular properties are recorded in chemical databases.
Earlier studies examined native GHRH(1–29), Sermorelin and other modified GHRH analogues, but these are not identical substances.
Published early human CJC-1295 studies appear to involve the long-acting DAC active moiety rather than Modified GRF 1-29.
The FDA did not identify pharmacological studies of CJC-1295 free base or CJC-1295 acetate.
What Did the FDA Find?
The FDA reviewed several CJC-1295-related bulk substances and concluded that inconsistent naming created uncertainty about which compound was being described. 3
Its review separated five forms:
- CJC-1295 free base, meaning the no-DAC active moiety;
- CJC-1295 acetate;
- CJC-1295 DAC free base;
- CJC-1295 DAC acetate; and
- CJC-1295 DAC trifluoroacetate.
The agency found that the human clinical references appeared to concern the DAC active moiety. It did not identify equivalent pharmacological studies for the no-DAC free-base or acetate forms.
What About Research on Natural GHRH?
Human studies have examined natural or unmodified GHRH(1–29) in controlled medical research. 4
Those studies help explain the GHRH receptor pathway, but they do not establish that Modified GRF 1-29 has an identical:
- Pharmacokinetic profile;
- Safety profile;
- Impurity profile;
- Duration of activity; or
- Clinical effect.
Structural similarity can support a research hypothesis. It cannot replace evidence involving the exact peptide being discussed.
Modified GRF 1-29 Compared with Related Peptides
These names sit within the same broad scientific area but describe different molecular structures.
| Material | General identity | Length | Main distinction |
|---|---|---|---|
| Modified GRF 1-29 | Tetra-substituted GHRH analogue | 29 residues | No DAC albumin-binding modification |
| CJC-1295 with DAC | Long-acting modified GHRH analogue | Modified peptide plus DAC-bearing lysine | Designed for covalent albumin association |
| Sermorelin | Amidated human GHRH(1–29) | 29 residues | Does not contain the four Modified GRF substitutions |
| Native GHRH | Naturally occurring signalling peptide | Full human form contains 44 residues | Natural sequence rather than a designed analogue |
| Tesamorelin | Modified human GHRH analogue | 44-residue GRF sequence with an N-terminal modification | Separate structure with its own pharmaceutical development |
| Ipamorelin | Synthetic pentapeptide | 5 residues | Acts through the ghrelin receptor rather than the GHRH receptor |
Modified GRF 1-29 and Sermorelin
Both are 29-residue GHRH-related peptides, but their sequences are not identical.
Modified GRF 1-29 contains four substitutions that Sermorelin does not. A certificate or study concerning Sermorelin should therefore not be used to authenticate Modified GRF 1-29.
Modified GRF 1-29 and Ipamorelin
These peptides act through different receptor systems and have completely different sequences.
Where both names appear in one blended material, the finished batch would require evidence confirming the identity and amount of each component.
How Should Modified GRF 1-29 Be Tested?
A useful analytical record should confirm the peptide that is present, not merely confirm that a peptide-like substance produced a large chromatographic peak.
Chromatography can separate detectable peptide-related components and provide relative peak-area purity.
Mass analysis can assess whether the observed molecular information is consistent with the expected no-DAC structure.
Fragmentation methods can add confidence about sequence order and the four substituted positions.
The observed data should be consistent with the absence of the additional DAC-bearing lysine and reactive modification.
Acetate, trifluoroacetate or another associated counterion may need separate measurement.
The report should distinguish peptide content from total dried material, water and associated salts.
What Should a Useful Certificate Include?
- The name Modified GRF 1-29 or tetra-substituted GRF 1-29
- A statement that DAC is absent
- The complete 29-residue sequence
- The substitutions at positions 2, 8, 15 and 27
- The C-terminal amide
- The expected molecular formula and mass
- The observed molecular identity result
- The chromatographic method and purity result
- The salt or counterion form
- The net peptide assay where available
- The batch number and analysis date
- The identifiable issuing laboratory
What Does 99% HPLC Purity Not Prove?
A high HPLC area result does not automatically prove:
- That the principal peak is Modified GRF 1-29;
- That all 29 residues are in the correct order;
- That the four substitutions are present;
- That DAC is absent;
- Which salt or counterion is present;
- The net peptide content;
- That the material matches a published study product;
- Sterility or suitability for administration.
The most useful certificate names the precise peptide, confirms its sequence and explains its material form. “CJC no DAC, 99%” is not a complete identity record.
What Is the UK Position?
No current UK marketing authorisation for a Modified GRF 1-29 or CJC-1295 without DAC medicinal product was identified in the official sources checked for this guide.
The MHRA determines whether a particular product falls within the legal definition of a medicinal product. 7
Its assessment considers matters such as:
- The substance and its pharmacological properties;
- Direct and implied claims;
- The primary intended purpose;
- The manner in which consumers are likely to use it;
- Labelling and packaging;
- Website and social-media presentation; and
- Customer reviews or instructions.
A research-use label does not override contradictory human-use claims, instructions or promotional imagery elsewhere.
Regulation 279 of the Human Medicines Regulations restricts advertisements for medicinal products without the required authorisation, registration or certificate. 8
Modified GRF 1-29 and Anti-Doping Rules
The 2026 World Anti-Doping Agency Prohibited List covers growth hormone-releasing hormone and its analogues. CJC-1295 is expressly named as an example. 6
Selling or describing the no-DAC material as Modified GRF 1-29 rather than CJC-1295 does not move it outside the GHRH-analogue category.
Anti-doping status is separate from UK product classification, laboratory purity and supplier labelling.
Medical and Editorial Review
This final article has been reviewed for medical context, scientific accuracy, evidence presentation, patient-safety language and editorial clarity by the multidisciplinary panel below.
The reviewers and contributors are identified to provide transparent authorship and accountability. Their inclusion does not represent endorsement of any research product, supplier, personal use, treatment claim or commercial statement discussed in this article.
Dr Laura Geige
Medical Director and Senior Aesthetics Practitioner at It’s Me & You Clinic, with a professional background in dentistry, medical aesthetics and cosmetic dermatology.
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Dr Rimas Geiga
Medical doctor with a professional interest in nutritional sciences, dietology, metabolic health and evidence-based preventative care.
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Dr Snieguole Geige
Dentist and medical doctor with experience across healthcare, preventative medicine and patient-centred clinical standards.
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Dr Giedre Narkiene
Medical doctor and board-certified dermatologist with expertise in medical and cosmetic dermatology, skin health and patient safety.
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Dr Veronika Matutyte
Medical doctor with training and professional experience in gerontology and healthcare management across clinical and hospital settings.
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Livija Samušienė
Qualified cosmetologist with a Bachelor of Health Sciences in cosmetology and a professional interest in skin health, acne and evidence-based aesthetic care.
Read professional profileFrequently Asked Questions About Modified GRF 1-29 UK
Clear answers about its name, sequence, evidence and laboratory identity.
What is Modified GRF 1-29?
It is a synthetic 29-residue analogue of the active portion of human growth hormone-releasing hormone, containing four amino-acid substitutions.
Is Modified GRF 1-29 the same as CJC-1295 without DAC?
The names are commonly used for the same no-DAC 29-residue active moiety. Modified GRF 1-29 is the more structurally informative name.
How many amino acids does it contain?
It contains 29 amino-acid residues and has a C-terminal amide.
Which four positions are modified?
The principal substitutions are D-alanine at position 2, glutamine at position 8, alanine at position 15 and leucine at position 27.
What does tetra-substituted mean?
It means that four amino-acid positions differ from the corresponding residues in native human GHRH(1–29).
Does Modified GRF 1-29 contain DAC?
No. It lacks the additional DAC-bearing lysine and albumin-binding reactive group.
Is no DAC simply a lower strength?
No. It is a different complete molecular structure, not merely a smaller quantity of CJC-1295 with DAC.
Was Modified GRF 1-29 studied in the published CJC-1295 human trials?
The published human CJC-1295 studies appear to concern the DAC-containing active moiety. They should not automatically be presented as studies of Modified GRF 1-29.
Is Modified GRF 1-29 the same as Sermorelin?
No. Both contain 29 residues, but Modified GRF 1-29 has four substitutions that Sermorelin does not.
Is Modified GRF 1-29 the same as Ipamorelin?
No. Ipamorelin is a separate five-residue peptide acting through a different receptor system.
Does HPLC prove that a sample is Modified GRF 1-29?
Not by itself. HPLC provides chromatographic information. Molecular identity requires suitable supporting analysis.
Does 99% purity prove that DAC is absent?
No. A peak-area purity figure does not by itself establish the complete structure or prove the absence of a DAC modification.
Is Modified GRF 1-29 authorised as a UK medicine?
No current UK marketing authorisation for a Modified GRF 1-29 medicinal product was identified in the official sources checked.
Is Modified GRF 1-29 prohibited in sport?
GHRH and its analogues are prohibited under current WADA rules. Changing the product name does not change the peptide class.
The Main Points to Remember
- Modified GRF 1-29 is a 29-residue GHRH analogue.
- It is commonly called CJC-1295 without DAC.
- It contains substitutions at positions 2, 8, 15 and 27.
- It does not contain the albumin-binding Drug Affinity Complex.
- It is structurally different from CJC-1295 with DAC.
- The published CJC-1295 human studies largely concern the DAC active moiety.
- Evidence involving DAC should not automatically be transferred to no DAC.
- HPLC purity alone does not confirm the complete sequence or absence of DAC.
- No current UK marketing authorisation was identified.
- GHRH analogues are prohibited under current WADA rules.
Scientific and Official Sources
- PubChem: CJC-1295 without DAC molecular record
- Jetté and colleagues: development of the long-acting CJC-1295 compound
- United States FDA: assessment of CJC-1295-related bulk substances
- Ranke and colleagues: controlled human research involving GRF(1–29)-NH2
- Rivier and colleagues: research into modified long-acting GRF analogues
- World Anti-Doping Agency: 2026 Prohibited List
- MHRA: Borderline products and how to tell if a product is a medicine
- Human Medicines Regulations 2012: Regulation 279
- United States FDA: current safety and characterisation concerns for CJC-1295-related substances
