Compare
Ipamorelin vs tesamorelin
Tesamorelin is an FDA-approved GHRH analogue with phase 3 trials; ipamorelin is unapproved with one randomised trial. A direct comparison.
By the Ipamorelin Research editorial team · Last reviewed · Scientific review: pending
Short answer
The central difference is not pharmacological but evidential. Tesamorelin is an FDA-approved drug with a phase 3 programme and approved labelling behind it. Ipamorelin is not approved, has one published randomised trial whose primary efficacy result was null, and was declined for the 503A compounding list by an FDA advisory committee in 2024. They also act at different receptors: tesamorelin at the GHRH receptor, ipamorelin at GHSR-1a.
| Field | Ipamorelin | Tesamorelin |
|---|---|---|
| Classification | Synthetic pentapeptide growth hormone secretagogue | Synthetic GHRH analogue (stabilised GHRH 1-44) |
| Receptor target | GHSR-1a | GHRH receptor |
| Molecular formula | C38H49N9O5 | C221H366N72O67S |
| Molecular weight | 711.9 | 5136 |
| Size | 5 residues, C-terminal amide; three non-standard residues | 44 residues, roughly seven times the mass of ipamorelin |
| Human clinical evidence | 1 randomised trial (null on efficacy); 1 dose-escalation PD study; 1 trial of 320 never reported | Phase 3 programme supporting an approved indication |
| Regulatory status | Not approved; FDA Category 2; advisory committee voted against 503A listing | FDA approved (BLA 022505, EGRIFTA) |
The evidence gap, stated plainly
Tesamorelin went through the full drug development process and has an approved application, BLA 022505, with the brand names EGRIFTA SV and EGRIFTA WR [openFDA]. Approval means randomised phase 3 trials, a regulatory review of their results, and approved labelling that states the indication, the population, the dose and the known risks.
Ipamorelin has none of that. A Drugs@FDA query returns no match [openFDA]. Its clinical programme consisted of two phase 2 trials in postoperative ileus: one published with a null efficacy result[Beck 2014], one of 320 patients that completed in 2014 and has never reported[NCT01280344]. FDA placed ipamorelin acetate in Category 2 for compounding [FDA Category 2], and in October 2024 an advisory committee voted 12 to 0 against adding it to the 503A Bulks List[PCAC minutes].
They are built differently and act differently
Tesamorelin is a 44-residue stabilised GHRH analogue at about 5,136 g/mol. Ipamorelin is a five-residue peptide at 711.9 g/mol — roughly a seventh of the mass [PubChem]. Tesamorelin works by mimicking growth hormone-releasing hormone at the GHRH receptor; ipamorelin works at GHSR-1a, the ghrelin receptor, which antagonist profiling established as distinct from the GHRH receptor [Raun 1998]. Both end at growth hormone release, by separate routes.
What is measured for ipamorelin in humans
One dose-escalation study in 40 healthy men measured a two-hour half-life and a single pulse of growth hormone peaking at 0.67 hours and declining to negligible concentrations at every dose [Gobburu 1999]. That is the complete human pharmacodynamic record. No human IGF-1 measurement after ipamorelin is indexed, and no human study has measured body composition. The human evidence page sets out all three human records.
For the approved compound, read its label
This site is an ipamorelin reference and does not attempt to summarise tesamorelin's evidence or risks. Tesamorelin has FDA-approved labelling, and that labelling — not this page and not any peptide site — is the authoritative source for what it does and what it can cause. The comparison tool sets ipamorelin against several compounds on the same verified fields.
References
- Raun K, Hansen BS, Johansen NL et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. PubMed 9849822 · doi:10.1530/eje.0.1390552[Animal, grade C]
- Gobburu JV, Agersø H, Jusko WJ et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. PubMed 10496658 · doi:10.1023/a:1018955126402[Human, grade B]
- Beck DE, Sweeney WB, McCarter MD et al. (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. PubMed 25331030 · doi:10.1007/s00384-014-2030-8[Human, grade A]
- ClinicalTrials.gov, U.S. National Library of Medicine (2011-04). Phase II Double-Blind Placebo-Controlled Dose Finding Study to Evaluate Safety/Efficacy of Ipamorelin Compared to Placebo for Recovery of Gastrointestinal Function Following Bowel Resection (NCT01280344). Source[retrieved 2026-11-11]
- U.S. Food and Drug Administration, openFDA. openFDA Drugs@FDA and NDC directory queries for ipamorelin. Source[retrieved 2026-11-11]
- U.S. Food and Drug Administration (2026-04-22). Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Source[retrieved 2026-11-11]
- U.S. Food and Drug Administration (2024-10-29). Pharmacy Compounding Advisory Committee Meeting Minutes, October 29, 2024. Source[retrieved 2026-11-11]
- PubChem, National Library of Medicine. Ipamorelin (CID 9831659). Source[retrieved 2026-11-11]