Ipamorelin had better nasal absorption (around 20% bioavailability) than other GH-releasing peptides, making it a candidate for non-injection delivery.
~20% nasal bioavailabilityIpamorelin absorbed significantly better through the nose than GHRP-2, GHRP-6, and other tested peptides
What the researchers 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.
Why it 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.
How the study worked
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.
What this study cannot tell us
Rat pharmacokinetics may not directly predict human absorption. Nasal bioavailability can vary significantly between species. Long-term nasal tolerability was not assessed.
How to read the evidence
Moderate evidence from a controlled comparative pharmacokinetic study in rats across multiple administration routes.
When this study was published
Published in 1998. Ipamorelin has since become one of the most studied GH secretagogues, though nasal delivery remains experimental.
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.
Questions still open
- Does ipamorelin maintain similar nasal bioavailability in humans?
- What structural features give ipamorelin superior nasal absorption?
- Could nasal ipamorelin achieve therapeutic GH release levels?
Common questions
What is ipamorelin?
Why is nasal delivery important for peptides?
Read the original research
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
Citation
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.