CJC-1295, Ipamorelin & Tesamorelin: GH Secretagogues Explained

CJC-1295, ipamorelin and tesamorelin are growth hormone secretagogues: peptides that prompt the pituitary gland to release its own growth hormone rather than supplying GH directly. CJC-1295 and tesamorelin are analogues of growth hormone-releasing hormone (GHRH), while ipamorelin acts on the ghrelin receptor. Tesamorelin is the only one with a marketing authorisation anywhere (FDA, 2010, as Egrifta); none is licensed by the MHRA, and all three are sold in the UK for laboratory research only.

This guide explains the two mechanisms, why CJC-1295 and ipamorelin are so often combined, what the published human and animal studies actually report, and what UK researchers need to know about legality and sourcing.

How growth hormone secretagogues work

Growth hormone is released from the anterior pituitary in pulses, controlled mainly by two hypothalamic signals: GHRH, which stimulates release, and somatostatin, which inhibits it. A third input, ghrelin, acts on the growth hormone secretagogue receptor (GHS-R1a) and amplifies the pulse. GH then drives the liver to produce IGF-1, which feeds back to suppress further GH release.

Secretagogues plug into this system at one of two points. GHRH analogues (CJC-1295, tesamorelin, sermorelin) mimic the stimulating signal. Ghrelin mimetics or GHRPs (ipamorelin, GHRP-2, GHRP-6, hexarelin) act on the ghrelin receptor. In research models the two classes are synergistic, which is the rationale for combining a GHRH analogue with a GHRP.

The theoretical attraction of this approach, discussed throughout the literature, is that it works within the body's existing feedback loops: rising IGF-1 still suppresses GH, so the pituitary retains a physiological ceiling that direct GH administration bypasses.

CJC-1295: the long-acting GHRH analogue

CJC-1295 is a modified 29-amino-acid fragment of GHRH developed by the Canadian company ConjuChem. Four amino acid substitutions protect it from enzymatic breakdown, and in the original version a Drug Affinity Complex (DAC) allows it to bind covalently to albumin in the blood, extending its half-life to roughly six to eight days.

The key human study is Teichman and colleagues, published in the Journal of Clinical Endocrinology and Metabolism in 2006. In healthy adults, single doses of CJC-1295 with DAC produced a two- to ten-fold rise in mean plasma GH lasting six days or more, and a 1.5- to three-fold rise in IGF-1 lasting nine to eleven days. The compound was being developed for HIV-associated lipodystrophy before the programme was discontinued in 2006, following an unrelated death in a trial participant that was judged not to be drug-related.

The version most commonly sold for research today is CJC-1295 without DAC, also called modified GRF (1-29). It has the same four substitutions but no albumin-binding tail, giving a half-life measured in minutes rather than days and a pulsatile rather than sustained profile in animal models.

Ipamorelin: the selective ghrelin mimetic

Ipamorelin is a pentapeptide developed by Novo Nordisk and characterised by Raun and colleagues in the European Journal of Endocrinology in 1998. It was the first GHRP shown to release GH with a selectivity comparable to GHRH itself. In the rat and pig models used in that work, ipamorelin stimulated GH release without the meaningful rises in cortisol, ACTH or prolactin seen with earlier GHRPs such as GHRP-6.

That selectivity is why ipamorelin became the preferred partner for CJC-1295 in research blends. Human data on ipamorelin is limited to early-phase studies, including a phase 2 programme for post-operative ileus that was discontinued for lack of efficacy on that endpoint. There are no completed late-stage trials and no marketing authorisation.

Tesamorelin: the only licensed GHRH analogue

Tesamorelin is a 44-amino-acid GHRH analogue with a trans-3-hexenoic acid group on the N-terminus to resist degradation. It was developed by Theratechnologies and approved by the US FDA in November 2010 as Egrifta for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy. It remains the only GHRH analogue with a marketing authorisation for any indication.

The approval rested on two phase 3 randomised, placebo-controlled trials led by Julian Falutz and published in the New England Journal of Medicine (2007) and the Journal of Clinical Endocrinology and Metabolism (2010). Over 26 weeks, tesamorelin reduced visceral adipose tissue by roughly 15 to 18% versus placebo, with the effect reversing after discontinuation. Later studies investigated tesamorelin in non-alcoholic fatty liver disease in people with HIV, reporting reductions in liver fat.

Tesamorelin does not hold a UK marketing authorisation from the MHRA, and the European application was withdrawn. Research-grade tesamorelin sold in the UK is not Egrifta, is not a medicine, and is supplied only as a laboratory reagent.

CJC-1295 vs ipamorelin vs tesamorelin: comparison

The table summarises the three compounds. The evidence column refers to the highest level of published human data for the compound itself.

Why CJC-1295 and ipamorelin are studied together

The combination reflects the physiology described above: a GHRH analogue raises the amplitude of the GH pulse, while a ghrelin mimetic increases the number of somatotroph cells that respond and blunts somatostatin. In animal and early human work, co-administration of a GHRH analogue with a GHRP produced a larger GH response than either alone.

For laboratories, a pre-filled blended pen removes the need to reconstitute two lyophilised vials and combine them at a fixed ratio, which reduces handling error. The trade-off is that a blend cannot isolate the contribution of each component, so single-compound pens remain the better choice for mechanistic studies.

Are CJC-1295, ipamorelin and tesamorelin legal in the UK?

All three are legal to buy, sell and possess in the UK as research chemicals. They are not controlled under the Misuse of Drugs Act 1971. The Act does control certain anabolic steroids and, since 2012, some substances associated with them, but GHRH analogues and GHRPs are not scheduled.

None of them has an MHRA marketing authorisation, so supplying them for human medicinal use, or promoting them with medicinal claims, breaches the Human Medicines Regulations 2012. UK suppliers therefore sell strictly for laboratory research, and the descriptions on this site are worded accordingly.

Sourcing GH secretagogues for research in the UK

Because these peptides are popular, they are also widely counterfeited or under-dosed. Tesamorelin is a 44-residue chain that is expensive to synthesise correctly, so a very cheap product is a warning sign. CJC-1295 is often mislabelled between the DAC and non-DAC versions, which have completely different pharmacokinetics.

1. Ask for a batch-specific certificate of analysis. Calibre pens are tested by Janoshik Analytical, with COAs published on the COA page.
2. Check the mass spectrometry result matches the expected molecular weight for the exact variant (CJC-1295 with DAC is roughly 3,650 Da; without DAC roughly 3,370 Da; tesamorelin roughly 5,136 Da).
3. Confirm HPLC purity; Calibre targets above 99%.
4. For blends, check that the COA reports both components separately.
5. Choose pre-filled, precision-made pens if consistent concentration between experiments matters more than flexibility of reconstitution.

Summary

CJC-1295, ipamorelin and tesamorelin all raise endogenous growth hormone in research models, but by different routes and with very different evidence bases. Tesamorelin has phase 3 trials and an FDA licence for a narrow indication; CJC-1295 has a well-cited 2006 human pharmacology study; ipamorelin has strong preclinical selectivity data and little else in humans. In the UK all three are legal research chemicals with no MHRA authorisation, and should be sourced with an independent certificate of analysis.