How Ipamorelin and Other Growth Hormone Peptides Are Absorbed by the Body
Ipamorelin had better nasal absorption (around 20% bioavailability) than other GH-releasing peptides, making it a candidate for non-injection delivery.
Quick Facts
What This Study Found
Ipamorelin demonstrated approximately 20% nasal bioavailability in rats, superior to GHRP-2, GHRP-6, and two other peptides, supporting its potential for non-invasive nasal delivery.
Key Numbers
How They Did This
Animal pharmacokinetic study in male rats. Five peptidyl GH secretagogues were compared following IV, subcutaneous, oral, and nasal administration. Plasma levels were measured to calculate bioavailability.
Why This Research Matters
Most peptide therapies require injections, which limits their practical use. Finding that ipamorelin absorbs well through the nasal route could make growth hormone-releasing peptide therapy more accessible and convenient.
The Bigger Picture
The delivery route is often the biggest practical barrier to peptide therapies. Nasal delivery offers a painless alternative to injections and better absorption than oral routes, which typically destroy peptides in the stomach.
What This Study Doesn't Tell Us
Rat pharmacokinetics may not directly predict human absorption. Nasal bioavailability can vary significantly between species. Long-term nasal tolerability was not assessed.
Questions This Raises
- ?Does ipamorelin maintain similar nasal bioavailability in humans?
- ?What structural features give ipamorelin superior nasal absorption?
- ?Could nasal ipamorelin achieve therapeutic GH release levels?
Trust & Context
- Key Stat:
- ~20% nasal bioavailability Ipamorelin absorbed significantly better through the nose than GHRP-2, GHRP-6, and other tested peptides
- Evidence Grade:
- Moderate evidence from a controlled comparative pharmacokinetic study in rats across multiple administration routes.
- Study Age:
- Published in 1998. Ipamorelin has since become one of the most studied GH secretagogues, though nasal delivery remains experimental.
- Original Title:
- Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption.
- Published In:
- Xenobiotica; the fate of foreign compounds in biological systems, 28(11), 1083-92 (1998)
- Authors:
- Johansen, P B(4), Hansen, K T, Andersen, J V, Johansen, N L
- Database ID:
- RPEP-00466
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What is ipamorelin?
Ipamorelin is a synthetic peptide that stimulates growth hormone release. It's considered one of the more selective GH secretagogues, meaning it boosts GH without significantly raising cortisol or other hormones.
Why is nasal delivery important for peptides?
Most peptides are destroyed by stomach acid if taken orally and typically require injections. Nasal delivery offers a painless, needle-free alternative that can achieve meaningful absorption for certain peptides.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00466APA
Johansen, P B; Hansen, K T; Andersen, J V; Johansen, N L. (1998). Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption.. Xenobiotica; the fate of foreign compounds in biological systems, 28(11), 1083-92.
MLA
Johansen, P B, et al. "Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption.." Xenobiotica; the fate of foreign compounds in biological systems, 1998.
RethinkPeptides
RethinkPeptides Research Database. "Pharmacokinetic evaluation of ipamorelin and other peptidyl ..." RPEP-00466. Retrieved from https://rethinkpeptides.com/research/johansen-1998-pharmacokinetic-evaluation-of-ipamorelin
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.