Peptide comparison
Ipamorelin vs Sermorelin
Ipamorelin and Sermorelin are both research peptides. This side-by-side compares their mechanism, typical research dosing, half-life, routes and safety so you can see how they differ. For research use only.
| Ipamorelin | Sermorelin | |
|---|---|---|
| Category | Hormonal | Hormonal |
| Overview | A selective ghrelin-receptor agonist that stimulates pulsatile GH release; human data limited and it is not an approved drug. | A synthetic 29-amino-acid fragment of GHRH that prompts the pituitary to release its own growth hormone; formerly FDA-approved for pediatric GH deficiency, now used off-label... |
| How it works | Ipamorelin binds and activates the GHS-R1a (ghrelin) receptor on anterior-pituitary somatotrophs. Receptor activation couples through Gq/phospholipase C, generating IP3 and mobilizing intracellular calcium, which drives GH secretion. This pathway is distinct from and complementary to GHRH, which signals via cAMP at the GHRH receptor; this mechanistic complementarity is the rationale for combining ipamorelin with GHRH analogs such as CJC-1295. Because it mimics endogenous ghrelin signaling, ipamorelin produces a pulsatile rather than continuous GH rise. Its defining preclinical property is selectivity for GH release with minimal effect on ACTH, cortisol, and prolactin. | Sermorelin binds and activates the GHRH receptor (GHRHR), a Gs-protein-coupled receptor on the somatotroph cells of the anterior pituitary. Activation raises intracellular cAMP, triggering pulsatile release of stored endogenous growth hormone. Because the stimulus acts upstream on the pituitary, the body's own negative-feedback loop (via IGF-1 and somatostatin) stays intact, which tends to limit supraphysiological GH excursions and preserve the natural pulsatile, diurnal pattern - a key contrast with directly injected recombinant GH. Sermorelin does not act at the ghrelin receptor (GHS-R1a), so its mechanism is distinct from the GHRPs; however, co-administering a GHRP (which suppresses somatostatin tone and activates GHS-R1a independently) produces additive or synergistic GH release, which is the rationale for GHRH/GHRP stacking. |
| Half-life | ~2 hours (terminal half-life in human PK studies; GH pulse peaks ~40 min post-dose) | Very short in plasma - roughly 10-12 minutes after intravenous administration, with subcutaneous dosing extending the effect curve only modestly because the peptide is rapidly degraded. Despite this rapid clearance it triggers a robust GH pulse that typically peaks 30-60 minutes after injection, which in turn drives IGF-1 production over the following hours. |
| Dosing reference | No approved clinical dosing exists; ipamorelin is not a licensed drug. In investigational human studies it was given intravenously. The Phase 2 postoperative ileus proof-of-concept trial in bowel-resection patients used intravenous ipamorelin 0.03 mg/kg twice daily for up to 7 days; it was well tolerated but did not significantly improve the primary efficacy endpoint versus placebo. Human pharmacokinetic studies administered single IV infusions to characterize the GH response. There is no established therapeutic dose for body composition, anti-aging, or performance use. | Established for its former pediatric indication. The FDA-approved pediatric dose was about 30 mcg/kg/day subcutaneously, given at bedtime to coincide with the natural nocturnal GH peak. Adult studies have used lower, weight-based doses - on the order of 0.5-3 mcg/kg subcutaneously at bedtime (one influential trial used a closely related analog, [Nle27]GHRH(1-29)-NH2, at about 2 mcg/kg/day for six months). Bedtime timing is consistently emphasized because it augments the dominant nocturnal GH pulse. |
| Routes | subcutaneous, intramuscular | subcutaneous, intravenous, intranasal |
| Safety & side effects | Human safety data are limited and short-term. In trials ipamorelin was generally well tolerated, consistent with its selective profile (minimal cortisol/prolactin perturbation). Plausible and reported effects relate to GH/IGF-1 elevation and ghrelin signaling: water retention, transient numbness or tingling, headache, flushing or injection-site reactions, lightheadedness, and possible effects on insulin sensitivity/blood glucose with sustained GH elevation. Theoretical longer-term concerns from chronic GH/IGF-1 excess include edema, joint pain, carpal-tunnel-like symptoms, and a theoretical concern about promoting growth of existing tumors; these are not established for ipamorelin specifically. It is research-use-only, not FDA-approved, and product purity/identity from research suppliers is not guaranteed. People who are pregnant, breastfeeding, have cancer, or have endocrine disease should not use it; not medical advice. | Sermorelin was well tolerated in both pediatric trials and adult studies. The most common adverse effects are injection-site reactions (redness, pain, swelling), transient facial flushing, and headache. Because it works upstream and the pituitary feedback loop stays intact, it does not produce the GH-excess (acromegalic) picture associated with high-dose exogenous GH, and chronic IGF-1 elevation - and its theoretical tumor-promotion concern - is less pronounced. Glucocorticoids can blunt the GHRH response. Long-term safety of adult off-label use has not been established in large trials, and compounded products have not undergone the regulatory scrutiny of the original approved drug, so purity and potency can vary. Sermorelin is prohibited in sport by WADA. This information is for research reference only and is not a recommendation for non-prescribed human use. |
For research use only. Not for human consumption. Always verify against current literature.