Revisiting: What a well-designed human trial of a secretagogue would look like posts 61–75

Pulsatile secretion matters because growth hormone is secreted in pulses, not continuously. A single post-dose growth hormone level is nearly uninterpretable. Assessing this class properly requires serial sampling or an integrated measure like IGF-1, and almost nothing published online does either.

IGF-1 as a surrogate: it is a better integrated measure than a spot growth hormone level and it is still a surrogate, with all the caveats that come with surrogates. Stable or rising IGF-1 is not the same as "this is working" in any health-related sense.

This follows post #60 rather than contradicting it.

Development history is more informative than speculation: ipamorelin was investigated clinically for post-operative ileus and was not taken forward to registration. That it was not brought to market tells you something about the cost-benefit calculation that any amount of forum enthusiasm does not.

Evidence quality in the secretagogue literature is honestly weaker than in the incretin literature. Large randomised controlled trials are rare. Most evidence is mechanistic or from small studies. This is why this subcategory has higher sourcing standards than most.

CJC-1295 with and without DAC: the version with a drug affinity complex binds albumin covalently and persists for days. The version without it does not persist. Supplier labelling frequently does not distinguish them clearly, so confirming which you have is important.

On post #62 — agreed on the reasoning, with one qualification.

Ipamorelin selectivity claims originate in preclinical characterisation and are reasonably well supported for what they claim: less effect on cortisol and prolactin than earlier GHRPs. Whether that translates to something clinically meaningful is a different question from whether the selectivity is real.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

What a well-designed human trial of a secretagogue would look like: randomised, placebo-controlled, adequate sample size, IGF-1 as primary outcome, muscle and strength as secondary outcomes, adequate follow-up duration. Very few secretagogue trials meet that description.

post #68 is right about the mechanism and I think understates the practical bit.

GHRH analogues versus ghrelin mimetics are often conflated but they are different mechanisms. GHRH analogues (like CJC-1295) cause the pituitary to release growth hormone. Ghrelin mimetics (like GHRPs) act on the ghrelin receptor directly. The effect on growth hormone secretion is similar but the mechanisms are distinct.

Tesamorelin has an approved indication in HIV-associated lipodystrophy. That is the only compound in this class with a registration-quality evidence base from a proper trial programme. Generalising from that narrow population to healthy adults is a substantial extrapolation.

IGF-1 as a surrogate: it is a better integrated measure than a spot growth hormone level and it is still a surrogate, with all the caveats that come with surrogates. Stable or rising IGF-1 is not the same as "this is working" in any health-related sense.

Pulsatile secretion matters because growth hormone is secreted in pulses, not continuously. A single post-dose growth hormone level is nearly uninterpretable. Assessing this class properly requires serial sampling or an integrated measure like IGF-1, and almost nothing published online does either.

On post #69 — agreed on the reasoning, with one qualification.

Reading a rodent study on a secretagogue without over-extrapolating: rodent studies can show a mechanism is plausible. They cannot show magnitude of effect in humans or safety profile in humans. That gap is larger for secretagogues than for incretin agonists because the human evidence is thinner.

post #73 answers the question as asked. The question underneath it is different.

Secretagogues and glucose tolerance: there is a mechanistic concern that sustained growth hormone elevation might impair glucose tolerance. The clinical relevance of this concern in practice is not well established.