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Is the 100mcg saturation dose for ipamorelin actually backed by data or just forum lore?

Posted by fasted_scientist in GH & Growth Peptides - 4 points, 4 comments.

Been seeing the 100mcg saturation dose thrown around everywhere for ipamorelin and GHRP-2, and ngl I cant actually find where that number comes from. Everyone repeats it like its gospel but when I dig into it, the original dose-response work on GHRPs was done with IV administration in healthy volunteers, not subcutaneous. The pharmacokinetics are completely different.

For me personally, 100mcg ipamorelin subq before bed seemed to do something for sleep quality, but I cant honestly tell you whether 200mcg was better or whether I was just sleeping better because I expected to. Could just be placebo. And I reckon a lot of the "I felt it more at 300mcg" reports are people chasing a feeling that isnt actually a bigger GH pulse.

The whole point of a saturation dose is that the pituitary has a finite releasable pool of GH at any given moment. Once youve maxed that out, more peptide doesnt give you more GH, it just gives you more side effects. But has anyone actually seen the dose-response curve for subcutaneous ipamorelin specifically? Because I havent, and I think people are extrapolating from IV data on older GHRPs and just assuming it carries over.

Would genuinely like to be wrong here. If someone has got a proper reference for the subq saturation number, cheers in advance. Otherwise I think we are all just guessing and repeating each other.

Comments

  • kenji_runs: Yeah i’ve been scratching my head over that 100mcg number too. The iv studies on ghrp‑2 and ipamorelin show a clear plateau around that dose, but subq absorption is patchy and bioavailability varies person to person. When i tried 100mcg ipamorelin subq before bed i did notice slightly deeper sleep, but bumping to 150mcg didn’t feel any stronger – could just be night‑to‑night variability or expectation bias. I’ve never seen a proper subq dose‑response curve for ipamorelin, most forums just copy
  • fasted_scientist: Ngl it is a bit of a mess. I reckon you are spot on about the iv data being the only thing people rely on. It is dodgy to assume the plateau looks the same when you are injecting into fat instead of a vein. Since you tried the 150mcg bump and felt nothing, do you reckon that confirms the saturation point is actually lower than the forum lore suggests? I am starting to think anything over 100mcg is just wasted money.
  • labrat_vik: You're right that the subq data basically doesn't exist, I've looked too and it's all back-referenced to the same IV work. The plateau concept probably carries over roughly but the actual number subq is gonna be a moving target depending on injection site, body fat, circulation, all that stuff. I noticed the same thing around 150mcg, felt no different than 100mcg, which either means saturation or just that sleep effects are too subtle to dose-titrate by feel.
  • fasted_scientist: Cheers for confirming I'm not just going mad looking for a study that doesnt exist. The 150mcg vs 100mcg thing you noticed is spot on with what I got at 200mcg, just couldnt tell the difference. The injection site variable is a I hadnt thought about, reckon abdominal subq vs glute could genuinely shift the absorption enough to change where saturation sits. Have you stuck with 100mcg or gone back up to experiment at all?

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