Sermorelin

In simple words

Sermorelin is the starting piece of a natural hormone that "wakes up" the pituitary gland and makes it release its own growth hormone. It is studied in older adults for preserving muscle mass and immunity.

What this molecule is

29 aa, the N-terminal fragment of GHRH(1-44): Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH₂. ~3358 Da.

Why it is studied

FDA-approved (Geref®). The most physiological GHRH analog. 6-month RCT in older adults (PMID: 9141536): ↑IGF-1, ↑lean body mass, ↑NK cells. Preserves somatostatin control: a physiological rhythm without supraphysiological peaks.

How it works

GHRHR → adenylate cyclase → ↑cAMP → ↑GH gene transcription → pulsatile release. Somatostatin control is preserved → physiological rhythm. Sermorelin "awakens" the pituitary rather than replacing GH.

Doses used in studies

Studies used 100-300 mcg SC at bedtime (synchronized with the nighttime GH peak) for a course of 3-6 months. In children, 30 mcg/kg/day was used; in practice, 15-30 mcg/kg/day.

Combined with in studies

• Ipamorelin — GHRH + GHRP = maximum effect
• GHRP-2
• Mod-GRF — less physiological, but more stable

Level of evidence

Level A Human clinical trials. There are randomized controlled trials (RCTs), or the compound has been approved by a regulatory agency. The most reliable level. FDA-approved. Human RCTs.

Important to know

⚠️ Geref® was withdrawn from the market (2008) for commercial reasons. Available through compounding in the US. Less effective with pronounced pituitary atrophy (few somatotrophs). T½ only 7 min: unstable vs Mod-GRF.

Studies in PubMed

1. Endocrine and metabolic effects of long-term administration of [Nle27]growth hormone-releasing hormone-(1-29)-NH2 in age-advanced men and women. (J Clin Endocrinol Metab, 1997)
2. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. (BioDrugs, 1999)
3. Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum Insulin-Like Growth Factor-1 Levels. (Am J Mens Health, 2017)
4. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. (Transl Androl Urol, 2020)
5. A potentially effective drug for patients with recurrent glioma: sermorelin. (Ann Transl Med, 2021)