Sermorelin Peptide

## What it is Sermorelin is a synthetic 29-amino-acid peptide identical to the active N-terminal fragment of endogenous human growth-hormone-releasing hormone (GHRH 1-29). The full-length endogenous GHRH is 44 amino acids; the 1-29 fragment retains essentially all GHRH-receptor activity, which made it an attractive synthetic target. Sermorelin received FDA approval in 1997 under the brand name Geref (Serono/EMD Serono) for diagnostic provocation and treatment of pediatric idiopathic growth-hormone deficiency. Geref was voluntarily discontinued from the US market by Serono in 2008. The discontinuation was a commercial decision rather than a safety or efficacy withdrawal: recombinant human growth hormone (rhGH) had captured the pediatric GHD market and the diagnostic role for sermorelin had been displaced by alternative provocation tests. The peptide retains its 1997 approval status on FDA records. Since the discontinuation, sermorelin has been compounded by 503A and 503B pharmacies for off-label adult anti-aging and body-composition use, predominantly through anti-aging clinics and specialty hormone-optimization practices. This is a meaningful regulatory distinction from the rest of the GHRP/GHRH peptides on this site: sermorelin is not a research-only compound but a discontinued FDA-approved drug actively prescribed via compounding. WADA places sermorelin on the Prohibited List under S2. ## Mechanism of action Sermorelin binds the GHRH receptor on pituitary somatotrophs, stimulating endogenous GH synthesis and pulsatile release. Because it acts on the pituitary rather than supplying exogenous GH, the negative feedback architecture of the GH-IGF-1 axis remains intact, theoretically reducing the risk of pituitary atrophy associated with chronic exogenous rhGH administration. The pulsatile release pattern produced by sermorelin more closely mimics physiologic GH secretion than continuous rhGH dosing. Plasma half-life is short, on the order of 10 to 20 minutes after subcutaneous injection. The brief pharmacokinetic profile produces a discrete GH pulse rather than sustained elevation. This is the structural reason sermorelin produces a more physiologic GH release than CJC-1295 with DAC, which produces sustained supraphysiologic GH; sermorelin's clearance allows the somatotroph to recover between pulses. Sermorelin and CJC-1295 no-DAC (Mod GRF 1-29) are pharmacologically very similar. Mod GRF 1-29 is sermorelin with four amino-acid substitutions designed to resist DPP-4 cleavage and slightly extend the activity window. In practice the two compounds produce comparable acute GH responses; the choice between them is largely about regulatory framing (sermorelin compounded under prescription vs Mod GRF 1-29 sold as research peptide) and clinical setting. ## Evidence base The pediatric GHD evidence base supporting the 1997 FDA approval is the most rigorous human dataset for any GHRH-class peptide. Multiple controlled trials in children with idiopathic short stature (totaling several hundred participants) demonstrated dose-dependent GH and IGF-1 elevation and modest but consistent gains in growth velocity over 6 to 12 months of daily dosing. Thorner 1996 and Pasqualini 1998 are representative. Adult use evidence is thinner. Khorram 1997 and Vittone 1997 conducted small RCT-grade trials in older healthy adults (n typically 20 to 50 per arm) reporting sustained IGF-1 elevation, modest improvements in lean mass, and reductions in fat mass over 16 weeks of daily dosing. The effect sizes are real but smaller than rhGH at equivalent IGF-1 elevation, which is partially attributable to the negative-feedback preservation that limits supraphysiologic IGF-1. No modern phase 3 RCT in adults has been completed. The post-discontinuation compounded use is supported by extrapolation from the original adult trials, the pediatric efficacy database, and the well-characterized pharmacology of GHRH receptor activation. The honest framing is that sermorelin has the strongest historical clinical foundation in the GHRP/GHRH class but lacks the contemporary RCT evidence in adult anti-aging populations that the marketing sometimes implies. ## Dosage and administration The historical Geref label for pediatric GHD was 0.03 mg/kg daily subcutaneously, typically dosed in the evening. Adult compounded protocols vary by clinic; common patterns are 200 to 500 mcg daily subcutaneously pre-bed, with some clinics dosing 200 to 300 mcg twice daily. Anti-aging clinic protocols frequently combine sermorelin with ipamorelin in the same syringe at pre-bed dose, on the rationale of synergistic GHRH and ghrelin pathway activation. A typical 5 mg compounded vial reconstituted with 2 mL bacteriostatic water gives 2.5 mg/mL. A 300 mcg dose draws 12 units on a U100 insulin syringe. Compounded vials may be supplied lyophilized or as a sterile aqueous solution depending on the pharmacy. Pre-bed dosing aligns with the largest endogenous GH pulse window during early slow-wave sleep, which is the standard rationale for the timing. Fasted dosing with a 30 to 60 minute window before food preserves the GH pulse; circulating glucose and free fatty acids suppress GH release. ## Side effects and safety The Geref-era safety database is the most substantial in the GHRP/GHRH class outside ipamorelin. Reported adverse effects in pediatric trials were mild and predominantly local (injection-site pain, irritation, occasional flushing). Adult trials reported similar profiles with rare reports of headache and vivid dreams. The peptide is generally considered well-tolerated within the modern compounded protocols. Long-term safety in chronic adult anti-aging use (years of daily dosing) is not formally characterized in completed trials. Theoretical concerns mirror the rest of the GH-axis class: insulin resistance with sustained GH/IGF-1 elevation (track fasting glucose and HbA1c), theoretical malignancy concern via IGF-1 axis activation, and pituitary downregulation with continuous use. Contraindications include pregnancy, active malignancy, history of pituitary tumor, diabetic retinopathy (theoretical worsening), and severe hypothyroidism (untreated hypothyroidism blunts GH response). Athletes face WADA sanctions; detection methods are validated. ## Practical notes Lyophilized sermorelin is stable refrigerated for the labeled shelf life. Once reconstituted with bacteriostatic water, refrigerate and use within 30 days. The Geref label specified refrigerated storage of the dry product as well, slightly stricter than research-peptide handling. For adults pursuing anti-aging or body-composition effects, the practical comparison is sermorelin vs CJC-1295 no-DAC: pharmacologically very similar, regulatory framing different (compounded prescription vs research peptide). Sermorelin has the stronger historical clinical foundation; CJC-1295 no-DAC has a slightly extended activity window from the four-amino-acid substitutions. Both are commonly paired with ipamorelin for synergistic GH release. Measurable IGF-1 elevation typically appears within 2 to 4 weeks of consistent daily dosing. Subjective sleep deepening from pre-bed dosing usually appears within the first week. Body-composition changes, if any, accumulate over 12 to 16 weeks with concurrent training and nutrition. Baseline IGF-1 and recheck at 8 weeks; absence of IGF-1 movement suggests under-dosed product or a non-responder phenotype.