Hormone selectivity during redesign

The parent peptide

The founding ipamorelin characterization tested rat pituitary cells, anaesthetised rats and conscious swine. It found potent growth-hormone release, while ACTH and cortisol remained at or below the response associated with growth-hormone-releasing hormone, even at doses more than 200-fold above the growth-hormone ED50.

That is a strikingly specific achievement. The word selective earns my respect in this acute hormonal experiment. The observation describes the measured hormone responses over the study's acute window; it leaves longer exposure and other outcomes to further work.

The comparison was with growth-hormone-releasing hormone. The finding describes relative hormone responses in acute preclinical tests.

The oral derivative

In the animal characterization of NN703, a structurally modified ipamorelin derivative achieved oral access in dogs. The characterization also reports a 50% cortisol increase at all tested doses, with no dose-dependent pattern. The derivative therefore warrants a separate hormonal assessment.

The experimental conditions and comparator would be essential before explaining why cortisol changed. Oral engineering leaves the derivative's hormonal profile as a question to investigate in its own right.

Selectivity and safety

The parent peptide's acute hormone result measured a particular kind of selectivity. A review assessing ipamorelin among peptide therapies describes scarce rigorous human safety data and the potential for serious harm. That wider safety question remains open beyond the appealing hormone comparison.

I would celebrate a cleanly defined pharmacological advantage and still ask for a human safety record suited to the proposed use. The human-studies page shows the kinds of exposure and outcomes that were actually measured for intravenous ipamorelin.