Tesamorelin and CJC-1295 are often mentioned in the same breath, and it is easy to see why. Both are synthetic analogues of growth hormone-releasing hormone (GHRH), both act on the same receptor in the pituitary, and both were designed to fix the same weakness in the natural hormone: it is broken down in the bloodstream within minutes. But the two compounds solve that problem in very different ways, they have very different development histories, and the research literature behind each one looks nothing alike.
This guide compares tesamorelin and CJC-1295 side by side: structure, how each one resists degradation, half-life, what the published studies actually measured, and how researchers tend to choose between them. It is written for Australian researchers working with Tesamorelin 10mg or CJC-1295 (no DAC) + Ipamorelin 10mg, and for anyone trying to make sense of the naming confusion around "CJC-1295", "Mod GRF 1-29" and "DAC".
Quick Comparison: Tesamorelin vs CJC-1295
| Feature | Tesamorelin | CJC-1295 (no DAC / Mod GRF 1-29) | CJC-1295 with DAC |
|---|---|---|---|
| Parent hormone | Full-length GHRH (1-44) | GHRH fragment (1-29) | GHRH fragment (1-29) |
| Length | 44 amino acids | 29 amino acids | 29 amino acids + lysine linker |
| Stabilising change | trans-3-hexenoyl group on the N-terminal tyrosine | Four amino acid substitutions | Same four substitutions + albumin-binding "Drug Affinity Complex" |
| Reported half-life | Roughly 26–38 minutes | Roughly 30 minutes | Roughly 6–8 days |
| Development status | Approved in the US (2010) as Egrifta for a specific indication | Never approved; research compound | Clinical development discontinued; research compound |
| Depth of human data | Large phase 3 trial programme | Limited | Small phase 1/2 pharmacology studies |
The Shared Starting Point: Why GHRH Needed Fixing
Natural GHRH is a 44-amino-acid peptide released by the hypothalamus. It binds the GHRH receptor (GHRH-R) on somatotroph cells in the anterior pituitary and stimulates the release of growth hormone. Early research showed that the first 29 amino acids, GHRH(1-29), carry essentially all of the biological activity, which is why so many analogues are built on that shorter fragment.
The problem for researchers is stability. Native GHRH is rapidly cleaved by the enzyme dipeptidyl peptidase-4 (DPP-4) between the second and third amino acids, and the inactive fragment that results is cleared quickly. Its functional half-life in circulation is only a few minutes. Every GHRH analogue in the research literature is, at heart, an attempt to slow that breakdown without losing receptor activity. Tesamorelin and CJC-1295 are two different answers to that question.
Tesamorelin: Full-Length GHRH With a Chemical Cap
Tesamorelin keeps the complete 44-amino-acid sequence of human GHRH. Its one modification is at the very start of the chain: a trans-3-hexenoyl group is attached to the N-terminal tyrosine. That small fatty-acid cap shields the vulnerable cleavage site from DPP-4, which makes the molecule considerably more stable than native GHRH while leaving the rest of the sequence, and its receptor binding, intact.
Tesamorelin was developed by Theratechnologies and is one of the few GHRH analogues to complete a full pharmaceutical development programme. The US Food and Drug Administration approved it in 2010 under the brand name Egrifta, for a single narrow indication in a specific patient group. That approval was based on two large randomised, placebo-controlled phase 3 trials, the first reported by Falutz and colleagues in the New England Journal of Medicine in 2007. The prescribing information for the approved product reports a mean elimination half-life of about 26 minutes in healthy volunteers and about 38 minutes in the trial population.
For researchers, the practical significance is that tesamorelin comes with an unusually deep body of controlled human pharmacology data: measured changes in growth hormone and IGF-1, imaging endpoints, and detailed tolerability reporting. Our Tesamorelin research guide covers those trials in more detail.
CJC-1295: A Modified GHRH Fragment, With or Without DAC
CJC-1295 was developed by the Canadian company ConjuChem. It starts from the shorter GHRH(1-29) fragment and makes four amino acid substitutions, at positions 2, 8, 15 and 27, chosen to resist enzymatic cleavage and improve stability. That tetra-substituted fragment on its own is often called "Modified GRF 1-29" or "Mod GRF 1-29", and in the research peptide market it is commonly sold as "CJC-1295 no DAC".
The name CJC-1295 originally referred to a version with one more addition: a Drug Affinity Complex (DAC). This is a reactive maleimide linker attached via an extra lysine residue, which allows the peptide to bind covalently to albumin in the blood. Because albumin circulates for weeks, the attached peptide is protected from clearance, and its half-life jumps from minutes to days.
What the CJC-1295 with DAC studies reported
The key published human data come from two 2006 papers in the Journal of Clinical Endocrinology & Metabolism. Teichman and colleagues reported that in healthy adults a single subcutaneous administration increased mean growth hormone concentrations several-fold for six days or more and raised IGF-1 for over a week, with an estimated half-life of around 6 to 8 days. Ionescu and Frohman reported that, despite the long exposure, the pulsatile pattern of growth hormone release was preserved, with the increase coming mainly from higher trough levels between pulses.
ConjuChem's clinical programme for CJC-1295 did not proceed to approval, and the compound has never been an approved medicine in any major market. As a result, the human data set is small compared with tesamorelin's.
The naming problem
Because "CJC-1295" is used for both versions, researchers should always confirm which one a vial actually contains. The difference is not cosmetic: a compound with a half-life of around 30 minutes and one with a half-life of around a week require completely different experimental designs and sampling schedules. A supplier's Certificate of Analysis should state the exact compound and show a mass spectrometry result consistent with its molecular weight; the DAC version is noticeably heavier.
Head-to-Head: The Differences That Matter in Research
1. Structure and receptor engagement
Both compounds are GHRH receptor agonists, so their primary mechanism is the same: they signal the pituitary to release growth hormone in a way that remains subject to the body's own feedback systems, including somatostatin. Tesamorelin uses the full native sequence, while CJC-1295 uses a truncated and substituted fragment. Neither acts on the ghrelin receptor; that is the territory of growth hormone secretagogues such as ipamorelin.
2. Duration of action
This is the biggest practical difference. Tesamorelin and CJC-1295 without DAC both produce short-lived exposure measured in minutes, which mimics a single pulse of natural GHRH. CJC-1295 with DAC produces sustained exposure over days. Researchers interested in pulse-like signalling generally work with the short-acting compounds; those studying prolonged elevation of the growth hormone axis have historically looked at the DAC version.
3. Quality of the evidence base
Tesamorelin has the stronger clinical evidence base by a wide margin, built on multi-centre phase 3 trials with hundreds of participants. CJC-1295 with DAC has a handful of small, well-designed pharmacology studies. CJC-1295 without DAC has the thinnest published human data of the three and is mostly studied in combination with other compounds.
4. Typical pairing
Because short-acting GHRH analogues and ghrelin-receptor agonists act through different receptors, CJC-1295 without DAC is very often studied together with ipamorelin, a selective pentapeptide secretagogue first characterised by Raun and colleagues in 1998. That pairing is why our CJC-1295 is supplied as a combined CJC-1295 no DAC + Ipamorelin 10mg vial. Tesamorelin is more often studied on its own, reflecting its clinical trial history. For more on combinations, see our CJC-1295 + Ipamorelin research guide and the Ipamorelin guide.
5. Molecular size and handling
Tesamorelin is a larger molecule (around 5,136 g/mol) than Mod GRF 1-29 (around 3,368 g/mol), which matters when converting between milligrams and molar concentrations in an experiment. Both are supplied as lyophilised powders and handled in the same way once reconstituted.
Handling, Reconstitution and Storage
Both compounds arrive as freeze-dried (lyophilised) powder. Sealed vials are best kept cool, dry and away from light, with freezer storage at around -20°C for the long term. After reconstitution, GHRH analogues are relatively fragile: they should be kept refrigerated at 2–8°C, protected from light and not subjected to repeated freeze-thaw cycles. Gentle swirling, rather than shaking, helps avoid damaging the peptide during mixing.
Reconstitution for multi-use research vials is usually done with bacteriostatic water, which contains 0.9% benzyl alcohol to limit microbial growth when a vial is accessed more than once. Our free peptide calculator works out concentration from vial size and diluent volume, and the peptide storage guide covers temperature, light and shelf life in more depth.
Which One Fits Your Research?
There is no single "better" compound; the choice depends on the question being asked.
- Choose tesamorelin when you want a full-length GHRH analogue with an extensive, peer-reviewed clinical pharmacology record to benchmark against.
- Choose CJC-1295 without DAC when you want a short-acting GHRH(1-29) analogue, particularly for work that pairs GHRH-receptor and ghrelin-receptor signalling.
- Consider the DAC version only when the study specifically requires sustained, multi-day exposure, and plan sampling around its much longer half-life.
Whichever compound you use, identity and purity come first. Optic Labs publishes batch results in our COA library, and both Tesamorelin 10mg and CJC-1295 no DAC + Ipamorelin are third-party HPLC tested and dispatched from Sydney. You can browse the full range in our peptides Australia collection or read the broader Peptides Australia research guide.
Frequently Asked Questions
Is tesamorelin the same as CJC-1295?
No. Both are GHRH analogues that act on the same pituitary receptor, but tesamorelin is the full 44-amino-acid GHRH sequence with an N-terminal trans-3-hexenoyl group, while CJC-1295 is a 29-amino-acid GHRH fragment with four amino acid substitutions, optionally with an albumin-binding DAC linker.
What is the difference between CJC-1295 with DAC and without DAC?
The version without DAC (also called Mod GRF 1-29) has a half-life of roughly 30 minutes. The DAC version carries a linker that binds albumin in the blood, extending its reported half-life to roughly 6 to 8 days. They require very different experimental designs.
Which has more published human research?
Tesamorelin, by a wide margin. It completed large phase 3 trials and was approved in the United States in 2010 for a specific indication. CJC-1295 has a small number of phase 1/2 pharmacology studies and was never approved.
Do tesamorelin and CJC-1295 work through the ghrelin receptor?
No. Both act on the GHRH receptor. Compounds such as ipamorelin act on the separate ghrelin (GHS-R1a) receptor, which is why CJC-1295 is often studied alongside ipamorelin.
Are these compounds permitted in sport?
No. Growth hormone-releasing factors, including GHRH analogues such as tesamorelin and CJC-1295, are on the World Anti-Doping Agency Prohibited List at all times.
How should tesamorelin and CJC-1295 be stored?
Store sealed lyophilised vials cool, dry and dark, with freezer storage for the long term. Once reconstituted, keep them refrigerated at 2–8°C, protect them from light and avoid repeated freezing and thawing.
This article is for educational and research purposes only. Optic Labs products are intended for research use only and are not for human consumption. Nothing in this article is medical advice. Always consult a qualified healthcare professional before considering any compounds.