Ipamorelin

What it is

Activates the ghrelin receptor, prompting the pituitary to release growth hormone. In pigs it raised growth hormone without the rise in the stress hormones ACTH and cortisol seen with GHRP-2 and GHRP-6.

What it is studied for

Ipamorelin was developed as a selective growth hormone releaser. In healthy men, intravenous infusions were used to model its blood levels and growth hormone response. A phase 2 trial in 114 bowel-surgery patients tested whether it shortened the time until they could tolerate a solid meal.

What the evidence says

Small human trials; animal research

In healthy men, growth hormone peaked about 40 minutes after an infusion and fell to low levels within hours. In the surgery trial it did not beat placebo. The authors called it well tolerated, but FDA noted two deaths in the ipamorelin group, though it is unclear whether they were drug-related, and more low potassium and high blood sugar.

How it was studied

Human studies gave ipamorelin by intravenous infusion; FDA found no human data on how it behaves when injected under the skin or given by other routes. Animal studies used injections and, in rats, oral dosing by tube; no study of a dissolving strip was found.