Endocrine and metabolic effects of long-term administration of [Nle27]growth hormone-releasing hormone-(1-29)-NH2 in age-advanced men and women
Khorram O, Laughlin GA, Yen SS
Journal of Clinical Endocrinology & Metabolism (1997) · n=19
Nineteen healthy adults aged 55–71 received nightly subcutaneous [Nle27]GHRH(1-29)-NH2 at 10 µg/kg or placebo for five months. Nocturnal GH and IGF-1 rose, lean-body-mass effects appeared in men, skin thickness rose in women — the load-bearing controlled adult sermorelin-analog trial whose modest scale defines the evidence ceiling for adult GHRH-axis modulation.
This is the Khorram, Laughlin, and Yen paper from the Department of Reproductive Medicine at UC San Diego, published in the Journal of Clinical Endocrinology and Metabolism in 1997 and standing today as the load-bearing controlled adult-human trial of a sermorelin-class GHRH analog in non-deficient older adults. The peptide tested was [Nle27]GHRH(1-29)-NH2 — a norleucine-27-substituted variant of the same 1-29 N-terminal GHRH fragment that is the basis of sermorelin itself — at 10 µg/kg nightly subcutaneous administration. The Nle27 substitution stabilises the peptide against methionine oxidation but the receptor pharmacology and the GH-releasing activity profile are equivalent to the parent fragment; the paper is universally cited in the sermorelin literature as the controlled adult-aging data point for the class.
The design was a randomised, placebo-controlled five-month crossover protocol in 19 healthy older adults (n=10 women, n=9 men) aged 55–71. Subjects received either the GHRH analog or placebo nightly by subcutaneous injection, with crossover after the active treatment window. Endpoints spanned the GH/IGF-1 biomarker axis (integrated 12-hour nocturnal GH levels, IGF-1, IGFBP-3), body-composition measures, insulin sensitivity, lipid panel, skin thickness, and quality-of-life instruments. The headline endocrine finding is the unambiguous biomarker response: 12-hour integrated nocturnal GH levels rose significantly versus placebo, IGF-1 and IGFBP-3 elevated within approximately two weeks of initiating the active treatment, and the GH/IGF-1 axis behaved as the GHRH-receptor mechanism would predict. The clinical-translation findings were partial and sex-asymmetric: men showed gains in lean body mass, improvements in insulin sensitivity by HOMA-style metrics, and self-reported improvements on general well-being and libido instruments; women showed increased skin thickness but did not demonstrate the same body-composition or insulin-sensitivity signal that the male sub-cohort showed. Adverse events were limited to transient hyperlipidaemia that resolved by the end of the five-month window; no serious adverse events were reported.
This paper is the controlled-trial backbone behind the contemporary off-label use of sermorelin in adult body-composition and longevity-adjacent protocols, and the Vittone et al. 1997 study published the same year is the parallel six-week shorter-duration trial in men. The honest evidence base for adult GHRH-axis modulation in healthy non-deficient older adults is essentially these two 1997 papers, plus the Walker 2006 editorial that re-frames the pharmacological argument, plus the subsequent open-label and observational practitioner literature; large RCTs in the indication that drives most current compounding-pharmacy prescribing have not been conducted.
The trial is small (n=19, with n=9 men) — a fit-for-purpose sample for biomarker-endpoint pharmacodynamic characterisation but underpowered for clinical-outcome inference. The five-month duration is the longest published controlled adult dosing of a sermorelin-class analog but is short relative to the chronic practitioner-protocol dosing the molecule is now used for. The crossover design is appropriate for pharmacodynamic and biomarker endpoints but is less well suited to body-composition and functional outcomes that drift on multi-month timescales. The protocol is single-blind rather than double-blind, which is a methodological limitation the paper acknowledges. The sex-asymmetric body-composition finding is consistent with the broader GH-axis literature (men generally show larger lean-mass responses to GH-axis stimulation than women) but should not be over-interpreted from a sub-cohort of n=9. The peptide tested ([Nle27]GHRH(1-29)-NH2) is a norleucine-substituted variant of the parent sermorelin sequence — it is the closest controlled-trial proxy in the literature but it is not bioidentical to clinical sermorelin (YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2) and the substitution-equivalence assumption is universally made in the practitioner literature without independent comparative pharmacology in the controlled setting. The trial population was healthy non-deficient older adults; the generalisability of the biomarker response to younger biohacker-use populations, to peri- and post-menopausal women, and to the polypharmacy contexts of typical compounding-pharmacy patients is not characterised here. The /peptides/sermorelin page treats this paper as the controlled adult-evidence backbone and the Khorram/Vittone pair as defining the modest scale on which the off-label adult use case rests.
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