# Ipamorelin's growth hormone pulse

> A hormone pulse at Oklahoma Functional Medicine — A hormone pulse at Oklahoma Functional Medicine: ipamorelin's acute selectivity in animals and its timing in healthy male volunteers.

**The hormone signal**

The signal is worth understanding on its own terms before asking it to explain a skeleton.

## Acute hormone selectivity

Ipamorelin's [founding characterization](https://pubmed.ncbi.nlm.nih.gov/9849822/) involved primary rat pituitary cells, anaesthetised rats and conscious swine. It released growth hormone potently, with no significant ACTH or cortisol elevation in that acute characterization. A secretagogue prompts secretion; the word describes a release of hormone.

The selectivity is a persuasive piece of pharmacology. I enjoy its fussy specificity: the result names the hormones that rose and the ones that did not. Its usefulness depends on preserving the setting: these were acute cell and animal experiments.

The adjective selective still has something substantial to say here. I simply give the hormone result its own space before moving to bone dimensions or eating after surgery. Those questions have outcomes of their own.

## The volunteer infusions

In the [human pharmacokinetic and pharmacodynamic study](https://pubmed.ncbi.nlm.nih.gov/10496658/), healthy male volunteers received intravenous infusions. There were 8 volunteers per dose level. The modeling described dose-proportional kinetics and a terminal half-life of approximately 2 hours; growth hormone responded as a single discrete pulse, peaking at about 40 minutes after dosing.

Pharmacokinetics follows the compound through the body. Pharmacodynamics follows the response to it. Here, those two kinds of measurement give a disappearance time and a response peak. The approximately 2-hour figure describes the elimination phase, when concentration is falling by half.

For me, separating the clocks is more satisfying than calling the molecule fast or slow. The hormone peak and the terminal half-life answer different questions, even though both are expressed in time. The study's intravenous setting and its healthy male population travel with the figures.

## The skeletal response

The rat [longitudinal bone-growth experiment](https://pubmed.ncbi.nlm.nih.gov/10373343/) recorded a change in growth without a change in total circulating IGF-1. That finding complicates a neat story in which the circulating measurement would explain the whole physical result.

I enjoy that complication more than an all-purpose claim about hormone optimization. The pulse can be characterized in volunteers, and the skeleton can be measured in rats, with the connection between them still requiring care. Side by side, they leave me a worthwhile question about the connection.

The [bone essay](/bone-dimensions) follows the dimensions. The [bowel essay](/return-to-eating) moves to a task the human trial could actually time: tolerating a meal after surgery.

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At Oklahoma Functional Medicine, published research about bodily function satisfies my curiosity; this editorial site runs no business and supplies no medical advice.