Sermorelin

Sermorelin made growth-hormone-deficient children grow faster, and it did so less well than growth hormone itself. In a randomised trial of 60 children whose deficiency started in the hypothalamus, height velocity after six months was 9.2 and 9.3 cm per year on two doses of sermorelin against 14.6 cm per year on growth hormone. That is a real effect, measured against an active comparator in a named population, and the comparison favours the other drug.

FDA approved it twice under the brand Geref: in 1990 as a test of whether the pituitary can secrete growth hormone, and in 1997 as a treatment for idiopathic growth hormone deficiency in children with growth failure. EMD Serono stopped marketing both products and asked FDA to withdraw the approvals, which FDA did effective 18 June 2009. In 2013 FDA determined that neither product had left the market for reasons of safety or effectiveness.

The use it is sold for today was never part of that programme. When eleven healthy men aged 64 to 76 injected it nightly for six weeks, overnight growth hormone went up while IGF-1, body weight, and DEXA muscle and fat did not move.

Sermorelin is a synthetic peptide matching the first 29 amino acids of human growth hormone-releasing hormone (GHRH), the hypothalamic signal that tells the pituitary to release growth hormone. A 1999 drug review describes it as the shortest synthetic peptide carrying the full biological activity of GHRH, and in 11 young adult volunteers the 1-29 fragment and the full-length 1-40 form produced identical growth hormone responses.

The peptide itself is gone within minutes. Infused intravenously at a constant rate in 10 healthy men, its disappearance half-time was 4.3 minutes. The growth hormone it releases lingers far longer: in 30 healthy men, levels stayed raised for about three hours after a single intravenous dose.

Its only approved form was Geref, made by EMD Serono. No approved sermorelin product exists today. It does not appear on FDA's Category 1 or Category 2 lists of bulk substances for compounding, and that absence says nothing either way about safety or legality.

It Asks the Pituitary, It Does Not Replace It

Sermorelin acts as an agonist at the GHRH receptor and stimulates growth hormone secretion from the anterior pituitary. Nothing in the vial is growth hormone. Every effect depends on a pituitary that can still answer the call, which is why its randomised paediatric trials enrolled children whose deficiency began in the hypothalamus, above a gland that could still respond.

Taller Pulses, Unchanged Rhythm

The cleanest human demonstration is a randomised peptide-clamp study. In healthy adult volunteers, 24 hours of continuous GHRH(1-29) under the skin raised the median growth hormone peak from 21.1 to 62.0 mU/L while the timing of pulses stayed the same. In 16 healthy older men and women, a single intravenous dose enlarged secretory pulses about fourfold, and deconvolution showed the rise came from more secretion, not slower clearance of growth hormone.

Where the Signal Stops

A bigger growth hormone pulse is the first step of a chain, and the human data show the chain breaking early. In that older-adult crossover, peak growth hormone reached 7.6 mcg/L against 1.2 on placebo, and IGF-1 did not change consistently. In children on six months of treatment, IGF-1 rose at first and then fell back to pretreatment values. In healthy older men injecting nightly for six weeks, growth hormone peak amplitude rose and IGF-1, IGFBP-3 and growth hormone binding protein stayed where they were.

The overreach with sermorelin borrows legitimacy from its real history and spends it on uses that history never covered.

Calling it FDA approved. It was, from 1990 and 1997, for a pituitary function test and for growth failure in children with idiopathic growth hormone deficiency. The company told FDA the products were no longer marketed and asked for withdrawal, and approval of both applications ended effective 18 June 2009. Sublingual and oral forms were never approved at any point.

Reading the 2013 determination as a safety endorsement. FDA reviewed its files, independently evaluated postmarketing adverse-event literature, and concluded the Geref products were not withdrawn for reasons of safety or effectiveness. The purpose of that finding is narrow: it lets FDA approve a generic application referring to Geref if every other requirement is met. It is a statement about why sales stopped, not a new approval and not a verdict on adult use.

Treating a growth hormone rise as the result. The rise is well documented. In healthy older adults it did not carry through to IGF-1 after one dose or after six weeks, and the six-week study found no change in body composition.

Borrowing evidence from other molecules. Tesamorelin, sold as EGRIFTA, is a separate GHRH analogue that went through its own FDA review for excess abdominal fat in HIV-infected patients with lipodystrophy. FDA's reviewers judged that Geref safety findings could not be extrapolated to it, and its trial results do not belong to sermorelin either. The same applies to IGF-1 rises measured on sermorelin combined with GHRP-2 and GHRP-6.

The safety record comes from paediatric trials and diagnostic use of a pharmaceutical product, and it is mostly mild.

According to FDA's 2010 review, the most common treatment-related adverse event in the Geref Pediatric trials was self-limited injection-site pain, redness or swelling, in about 16 percent of patients. Facial flushing, headache, dizziness, somnolence, hyperactivity, dysphagia and urticaria each occurred in under 1 percent. After single diagnostic doses, flushing, pallor, headache, nausea, vomiting, a metallic taste and chest tightness were reported rarely. None of the trial abstracts read here reports a discontinuation rate for adverse events.

Antibodies were the norm. In the 60-child randomised trial, all 20 children on the high dose and 19 of 20 on the low dose developed anti-GHRH antibodies, which had almost disappeared nine months after stopping. Titres did not correlate with growth, and FDA's review notes the antibodies were not associated with generalised allergic reactions.

The response also faded. Over a year of treatment in short children, overnight growth hormone and the growth hormone response to GHRH testing both fell, while fasting glucose and insulin rose. Growth then slowed below baseline for three months after stopping. A 2018 review of growth hormone secretagogues noted that no safety data on malignancy or mortality were available for the class.

All of this was measured on Geref under trial supervision. No approved manufacturer exists now, so none of it describes what is in a vial sold today.

Sermorelin deserves a more respectful reading than most compounds in its category and a more skeptical one than its marketing gets. Both follow from the same trials.

What the evidence supports: it reliably releases growth hormone from a working pituitary, it accelerated growth in children with hypothalamic growth hormone deficiency, and it served as a reasonably specific diagnostic test whose normal result could still miss a quarter of deficient children. Against growth hormone, it lost on growth velocity in one randomised trial and on bone-age-adjusted height in the other.

What the evidence does not support: a change in body composition, sleep or ageing in healthy adults. The six-week study in older men found no change in body composition, and IGF-1, the hormone most downstream claims depend on, did not move. Two of six strength measures improved in that uncontrolled study, which is a lead rather than a result.

The useful position is to know what Geref was, know that the approval covered children and a pituitary test, and know that a growth hormone rise in an adult is where the documented effect ends.

Not an approved medicine today. Both Geref approvals were withdrawn effective 18 June 2009 after the company stopped marketing them, and no approved sermorelin product has existed since.

Not shown to change body composition in healthy adults. Six weeks of nightly injections in men aged 64 to 76 left DEXA muscle and fat, weight and IGF-1 unchanged.

Not a match for growth hormone where it was approved. In 60 deficient children randomised head to head, growth hormone produced 14.6 cm per year against 9.2 and 9.3 on sermorelin.

Not tesamorelin. Tesamorelin is a different GHRH analogue with its own approval for HIV-associated abdominal fat, and its results do not transfer.

Not permitted in tested sport. WADA prohibits it at all times under S2.2.4, where it is named among the GHRH analogues.

Sermorelin sits at Controlled human trials because the randomised trials exist, and I am not going to talk it down to make a point. It was a real medicine with a real trial programme, it accelerated growth in the children it was approved for, and FDA has said in writing that it did not leave the market over safety.

What I will not do is let that history stand in for evidence it does not contain. Every controlled trial asked a paediatric or diagnostic question. When healthy older men took it for six weeks and had their bodies measured, growth hormone rose and their body composition did not change. Both of those facts are true, and the second one is the one most people never hear.

So my confidence here is high and narrow. I am confident it releases growth hormone, confident it helped deficient children grow and helped less than growth hormone did, and confident that no controlled study has shown it changing an adult body. I will not publish doses, and I will not treat a compounded vial as the Geref that was studied.