What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide — meaning it's a tiny protein made of just five amino acid building blocks. Its full chemical name is Aib-His-D-2-Nal-D-Phe-Lys-NH2, but the important thing to know is what it does: it tells the pituitary gland (a pea-sized gland at the base of the brain) to release growth hormone (GH).[3] That makes it a growth hormone secretagogue — "secretagogue" just means something that triggers secretion of another substance.
Ipamorelin is a research compound. It is not approved for human use by the FDA or equivalent regulatory bodies, and everything discussed here refers strictly to preclinical (animal) research.[6]
How Ipamorelin Works
Think of the pituitary gland like a locked safe full of growth hormone. Ipamorelin is a key — specifically, it fits into a receptor called the GHS-R1a (growth hormone secretagogue receptor). When ipamorelin slots into that receptor, the safe opens and a pulse of GH is released into the bloodstream.[3]
What makes ipamorelin stand out from older GH-releasing peptides? Selectivity. Many similar compounds also trigger the release of cortisol (a stress hormone) and ACTH (which signals the adrenal glands). In animal studies, ipamorelin did not meaningfully raise cortisol or ACTH — even at doses more than 200 times higher than what was needed to release GH.[3] It also had no effect on other pituitary hormones like FSH, LH, prolactin, or TSH.[3] That selective profile is why researchers called it "the first selective growth hormone secretagogue" back in 1998.[3]
Once GH is released, it travels to the liver and other tissues, where it stimulates production of IGF-1 (insulin-like growth factor 1) — the downstream messenger responsible for many of GH's effects on muscle, bone, and metabolism. Researchers studying ipamorelin in the context of musculoskeletal repair describe this IGF-1 signaling pathway as central to its potential tissue effects.[1]
What the Research Shows
Bone Growth
In a 1999 rat study, ipamorelin was injected three times daily for 15 days. Researchers measured how fast the tibia (shin bone) was growing using a fluorescent dye technique. The result: ipamorelin dose-dependently increased the rate of longitudinal bone growth — from about 42 micrometers per day in untreated animals up to 52 micrometers per day at the highest dose tested. Body weight gain also increased in a dose-dependent way.[4] See the dosage chart on this page for the specific dose ranges used.
Muscle Recovery
When combined with CJC-1295 (another GH-releasing peptide), ipamorelin showed significantly improved maximum muscle tension in mouse models of glucocorticoid-induced muscle loss — though these findings are limited to animal studies and have not been validated in humans.[2]
Gastrointestinal Function
Ipamorelin has been studied for its effects on gut motility (how quickly things move through the intestines). Preclinical work examined it across a wide dose range, both as a single dose and with repeated dosing over two days, in models of postoperative ileus — a condition where the gut slows down after surgery. The dosage chart on this page details the ranges tested.
Weight Loss and Chemotherapy
In a 2024 ferret study, ipamorelin was tested alongside another GH secretagogue (anamorelin) in animals given cisplatin — a chemotherapy drug notorious for causing nausea and weight loss. Ipamorelin (administered intraperitoneally at 1–3 mg/kg daily for three days) reduced cisplatin-associated weight loss during the delayed phase by approximately 24%.[5] It did not, however, affect the emesis (vomiting) itself — that anti-nausea effect was seen only with anamorelin given directly into the brain, suggesting that brain penetration matters for the anti-emetic mechanism.[5]
Musculoskeletal and Sports Medicine Interest
Several recent reviews note that ipamorelin is among the peptides generating interest in orthopaedics and sports medicine for tissue repair and recovery.[1][2][6] However, all reviewers are consistent on one point: rigorous human safety and efficacy data are currently lacking, and clinical recommendations cannot yet be made.[2][6]
What Ipamorelin Is Being Studied For
- Stimulating GH pulses and studying downstream IGF-1 signaling[3]
- Longitudinal bone growth in preclinical models[4]
- Muscle preservation and recovery in animal models[2]
- Gastrointestinal motility (postoperative ileus models)[3]
- Attenuation of chemotherapy-related weight loss[5]
- Potential applications in musculoskeletal repair (preclinical only)[1][6]
How Ipamorelin Is Dosed in Research
Preclinical dose ranges for ipamorelin vary widely depending on what's being studied — from microgram-level doses for GH and bone-growth work, to milligram-level doses in weight-loss and pain models. Rather than restate every number here, we've compiled all published preclinical dose ranges, schedules, and durations in the dosage chart on this page. You can also use our calculator to explore how researchers have scaled doses across different study parameters. Remember: these are research reference figures only, not dosing instructions for humans.
Mixing and Storing Ipamorelin
In research settings, ipamorelin typically arrives as a lyophilized powder — a freeze-dried cake sealed in a sterile vial. To prepare it for use, researchers add bacteriostatic water (sterile water with a small amount of benzyl alcohol to prevent bacterial growth) slowly along the inside wall of the vial, never directly onto the powder. The vial is then gently swirled — never shaken — until the powder fully dissolves into a clear solution. Once reconstituted, the solution is stored in a refrigerator (around 2–8°C / 36–46°F) and is generally considered stable for up to 28 days when kept cold and away from light. Unconstituted powder should be kept frozen or refrigerated in a dark, dry environment. Always label vials with the reconstitution date. These are standard laboratory handling practices; consult the supplier's certificate of analysis for product-specific guidance.
Sources
- Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. — Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews, 2026. PMID 41490200.
- Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. — The American journal of sports medicine, 2026. PMID 41476424.
- Ipamorelin, the first selective growth hormone secretagogue. — European journal of endocrinology, 1998. PMID 9849822.
- Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. — Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society, 1999. PMID 10373343.
- The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism. — Physiology & behavior, 2024. PMID 39043357.
- Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. — Sports medicine (Auckland, N.Z.), 2026. PMID 41966639.
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