Comparison. Research use only.
Tesamorelin vs Ipamorelin
Tesamorelin is a GHRH analog that stimulates the pituitary directly, and it has been investigated in adipose-tissue compartment research. Ipamorelin is a ghrelin-mimetic GH secretagogue that produces a discrete GH pulse. Different upstream targets, overlapping downstream GH effects.
What is the difference between Tesamorelin and Ipamorelin?
Tesamorelin is a GHRH analog that activates the GHRH receptor on pituitary somatotrophs; Ipamorelin is a pentapeptide that acts as a partial agonist at the ghrelin receptor (GHS-R1a). Both lead to pulsatile growth hormone release, but through different receptors. Tesamorelin is FDA-approved (Egrifta) after Phase 3 trials, whereas Ipamorelin's only human trial, a Phase 2 study, did not meet its endpoint.
| Attribute | Tesamorelin | Ipamorelin |
|---|---|---|
| Molecule class | Synthetic GHRH analog with an N-terminal trans-3-hexenoic acid group | Synthetic pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH2) |
| Molecular weight | 5135.89 Da | 711.85 Da |
| Receptor target | GHRH receptor (GHRHR) | Ghrelin receptor (GHS-R1a), partial agonist |
| Intracellular signalling | Gsα / adenylyl cyclase / cAMP / PKA | Gq/PKC |
| Human evidence | Phase 3 RCTs in HIV lipodystrophy (Falutz et al., NEJM 2007, n=412; JAIDS 2010, n=404) | One Phase 2 RCT (Beck et al., 2014, n=114): no significant difference vs placebo |
| Regulatory status | FDA-approved as Egrifta (2010) for one indication | Investigational; not approved |
| WADA | Prohibited (S2, GHRH analog) | Prohibited (S2, GH secretagogue) |
What is Tesamorelin?
Tesamorelin is a synthetic analog of human growth hormone-releasing hormone (GHRH, also known as somatocrinin), with a trans-3-hexenoic acid group attached to the N-terminus. That modification makes it resistant to cleavage by dipeptidyl peptidase-4 (DPP-4), the enzyme that normally breaks GHRH down, so it stays active longer than native GHRH(1–44).
Read the full Tesamorelin research summary →What is Ipamorelin?
Ipamorelin is a selective growth hormone secretagogue pentapeptide, a five-amino-acid chain that prompts the pituitary to release its own growth hormone. It acts as a partial agonist at the ghrelin receptor (GHS-R1a), stimulating pulsatile GH release from pituitary somatotrophs.
Read the full Ipamorelin research summary →Tesamorelin and Ipamorelin specifications
Frequently asked questions
Do Tesamorelin and Ipamorelin act on the same receptor?
No. Tesamorelin binds the GHRH receptor on pituitary somatotrophs and signals through Gsα, adenylyl cyclase and cAMP. Ipamorelin binds the ghrelin receptor, GHS-R1a, as a partial agonist. Both receptors sit on the same pituitary cells and both lead to pulsatile growth hormone release, which is why Tesamorelin and Ipamorelin are compared, but their upstream targets are distinct.
Have Tesamorelin and Ipamorelin been studied in humans?
Tesamorelin has the larger human record: Phase 3 randomized trials in HIV-associated lipodystrophy (Falutz et al., NEJM 2007, n=412; Falutz et al., JAIDS 2010, n=404) supported its FDA approval as Egrifta. Ipamorelin was tested in one Phase 2 trial in post-operative ileus (Beck et al., 2014, n=114), where it was well tolerated but did not differ significantly from placebo.
Why are Tesamorelin and Ipamorelin compared?
Tesamorelin and Ipamorelin are both growth hormone secretagogues: they prompt the pituitary to release its own growth hormone rather than supplying it from outside. Researchers compare them because they reach the same downstream axis, GH and then IGF-1, from two different upstream receptors, and because their evidence bases differ sharply in size.
What is the regulatory status of Tesamorelin and Ipamorelin?
Tesamorelin is FDA-approved as Egrifta for reduction of excess abdominal fat in HIV-infected adults with lipodystrophy; other uses are investigational. Ipamorelin is investigational and not approved by the FDA or any other regulatory agency. WADA prohibits both under section S2: Tesamorelin as a GHRH analog and Ipamorelin as a GH secretagogue.
Other research peptide comparisons
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