Sermorelin: the GHRH fragment that was an approved drug

What sermorelin is

Natural growth hormone-releasing hormone (GHRH) has 44 amino acids. Sermorelin corresponds to its first 29, with an amidated end: GHRH(1-29)NH2. It is the shortest synthetic peptide that retains the full biological activity of GHRH, and it specifically stimulates GH secretion from the anterior pituitary¹. Its chemical profile and sequence are on the sermorelin page.

Unlike recombinant GH, sermorelin does not supply the hormone from outside: it acts on the GHRH receptor and lets the pituitary release its own GH, which in turn raises IGF-1¹⁴. That difference in mechanism is at the center of almost all the interest it draws from researchers.

An approved drug that left the market

Sermorelin held two U.S. approvals under the GEREF brand. The 0.05 mg presentation (NDA 19-863), approved on December 28, 1990, was indicated for evaluating the pituitary's ability to secrete GH. The 0.5 and 1.0 mg presentation (NDA 20-443), approved on September 26, 1997, was indicated for treating idiopathic GH deficiency in children with growth failure².

In 2008 the holder notified the FDA that both presentations were being discontinued, and the agency withdrew the approvals effective June 18, 2009. In 2013, after reviewing its files and the postmarketing adverse-event literature, the FDA determined that both products "were not withdrawn from sale for reasons of safety or effectiveness". That determination allows generic versions to be approved if they meet all other requirements². The document does not detail the commercial reason for the discontinuation.

The pediatric trials

The pivotal study is the GEREF International Study Group trial published in 1996: 110 prepubertal children with GH deficiency, previously untreated, received subcutaneous GHRH(1-29) once daily at bedtime for up to one year, in a multicenter open-label study without a control group; 86 were included in the efficacy analysis. Mean growth velocity went from 4.1 cm/year to 8.0 cm/year at 6 months and 7.2 cm/year at 12 months; 74% had a good response at 6 months. Bone age advanced in proportion to height age (ratio 1.04, not significantly different from 1), there was no change in fasting glucose and no excessive IGF-1 generation, and treatment was well tolerated³.

A 1999 review summarized the profile: intravenous sermorelin was a rapid and relatively specific diagnostic test, with fewer false positives than other provocative tests; the most frequent adverse effects were transient facial flushing and injection-site pain. The same review noted that the recommended dose had not been compared directly with somatropin; with other schedules (continuous infusion or three daily doses), growth-velocity gains were smaller than with daily somatropin, and the effect on final adult height had not been determined¹.

Older adults: what the studies showed

At the U.S. National Institute on Aging, 10 men aged about 68 received GHRH(1-29) twice daily for 14 days. At the high dose, 24-hour GH and IGF-1 rose until they no longer differed from those of 9 young men, with no change in fasting glucose, blood pressure or laboratory tests⁴.

With a single nightly injection for 6 weeks, in 11 men aged 64 to 76, nocturnal GH rose but IGF-1 did not change; 2 of 6 strength measures improved, with no change in DEXA body composition. The authors concluded that "single nightly doses of GHRH are less effective than multiple daily doses"⁵. In 19 men and women aged 55 to 71, in a single-blind trial with a 4-week placebo lead-in, 16 weeks of an analog, [Nle27]GHRH(1-29)NH2, raised GH and IGF-1, and lean mass and insulin sensitivity increased in men only; IGF-1 returned toward baseline by 16 weeks⁶. In 89 healthy adults aged about 68, 6 months of daily GHRH were associated with better performance on several cognitive tests versus placebo⁷.

The pulsatility argument

The reason sermorelin stays in the conversation is physiological. According to the National Institute on Aging investigators, in GH-deficient children and young adults GHRH raises GH and IGF-1 "while preserving physiological GH release"⁴. In treated children there was no excessive IGF-1 generation³. The response remains subject to the axis's own regulation, something exogenous GH lacks.

The contrast with recombinant GH in healthy older adults is instructive. A systematic review of 18 study populations found −2.1 kg of fat and +2.1 kg of lean mass, with no weight change, but more edema, arthralgias, carpal tunnel syndrome and gynecomastia, and somewhat more diabetes and impaired fasting glucose; it concluded that "GH cannot be recommended as an antiaging therapy"¹⁰. In a 26-week trial in 131 adults aged 65 to 88, diabetes or glucose intolerance occurred in 18 GH-treated men versus 7 not receiving GH¹¹. These data are for exogenous GH; no trial has directly compared its safety with that of sermorelin in adults.

Short half-life: advantage and limit

GHRH(1-29)NH2 is cleared in minutes: in an intravenous infusion in 10 healthy men, its disappearance half-time was 4.3 minutes⁸. Even so, after an intravenous injection GH stayed elevated for about 3 hours⁹. That profile produces brief GH pulses, consistent with physiology, but it explains why a single nightly dose had limited effects on IGF-1⁵.

Industry answered with more stable analogs. Tesamorelin, a GHRH analog with a current U.S. approval for excess abdominal fat in HIV with lipodystrophy¹³, has phase 3 trials reviewed in Tesamorelin: the GHRH analog that did get through the FDA. Long-acting secretagogues and ghrelin agonists are reviewed in CJC-1295, ipamorelin and MK-677: the GH and IGF-1 debate.

Where the evidence ends

• The approved efficacy evidence is pediatric. The registered indications were diagnosis of somatotroph function and idiopathic GH deficiency in children²; the effect on final adult height had not been determined¹.
• The older-adult studies are small and short. They enrolled 10 to 89 participants, for 2 weeks to 6 months, with intermediate measures such as GH, IGF-1 or cognitive tests, not hard clinical outcomes⁴⁵⁶⁷.
• Not all used the same molecule. One of the most cited adult studies used an analog, [Nle27]GHRH(1-29)NH2, not sermorelin itself, and the abstract of the cognitive trial does not specify the GHRH form used⁶⁷.
• Results vary with schedule and sex. A single nightly dose did not raise IGF-1⁵, and changes in lean mass and insulin sensitivity appeared only in men⁶.
• Today's product is not the original GEREF. A 2026 review points to uncertainty about the composition and dose of GH-axis peptides in unregulated supply chains¹².