WIKIPEPTIDE

Peptide class

GHRH Analogues

Synthetic analogues of growth hormone-releasing hormone (GHRH) that bind the GHRH receptor on pituitary somatotrophs, amplifying pulsatile growth hormone secretion through the physiological hypothalamic-pituitary axis.

Class Members

Compound Mechanism Primary Use Profile
CJC-1295 (with DAC) Long-acting GHRH analogue; DAC modification extends half-life to ~6–8 days via albumin binding GH axis support, body composition, anti-aging research View page
Sermorelin Short-acting GHRH 1–29 fragment; half-life ~10–20 min GH deficiency research, physiological GH axis stimulation Coming soon
Tesamorelin GHRH analogue with trans-3-hexenoic acid modification; FDA-approved for HIV lipodystrophy Visceral adiposity reduction, metabolic research View page

How This Class Works

GHRH is a 44-amino acid hypothalamic peptide that binds the GHRH receptor (GHRHR) on pituitary somatotrophs — the specialized cells responsible for GH synthesis and secretion. Receptor activation triggers adenylyl cyclase → cAMP → PKA signalling, which increases GH gene transcription and promotes GH vesicle exocytosis. GHRH analogues mimic this signal with greater potency and longer duration than endogenous GHRH.

Endogenous GHRH has a half-life of only 1–2 minutes due to rapid proteolytic degradation. GHRH analogues have been engineered to resist enzymatic degradation. Sermorelin uses only the first 29 amino acids (the receptor-active region) with some resistance modifications. CJC-1295 adds the Drug Affinity Complex (DAC) technology — a lysine-reactive group that covalently binds circulating albumin, extending half-life from ~30 minutes to 6–8 days. Tesamorelin adds a trans-3-hexenoic acid moiety to the N-terminus.

Unlike GHRPs, GHRH analogues are subject to somatostatin (somatotropin-inhibiting hormone) gating. When somatostatin tone is high — typically during the first half of sleep — GHRH analogue efficacy is reduced. This is why Sermorelin protocols commonly specify injection at bedtime to align with the natural low-somatostatin window around sleep onset. This interaction does not affect GHRPs (which are insensitive to somatostatin via their distinct receptor mechanism), which is the pharmacological basis for combining both classes.

Research Context

GHRH was characterized and synthesized in the early 1980s by the groups of Guillemin and Schally (Nobel Prize in Physiology or Medicine, 1977, for related work). Sermorelin was approved by the FDA for childhood GH deficiency in the 1990s but withdrawn from commercial availability in 2002. Tesamorelin (Egrifta) is approved for HIV-associated lipodystrophy and has published Phase 3 data.

Research has investigated GHRH analogues for their potential role in age-related GH decline, body composition, recovery, and metabolic health. The hypothesis that declining GH pulsatility with age may be partially addressable by GHRH axis stimulation (rather than direct GH replacement) has motivated research into these compounds as a more physiological approach.

Individual Compound Notes

CJC-1295 (with DAC)

The long half-life (~6–8 days) enables once- or twice-weekly dosing, making it the most convenient GHRH analogue for research protocols. The DAC modification works by covalently binding to serum albumin at lysine sites. Commonly combined with Ipamorelin in the CJC-IPA research stack.

Sermorelin

A short-acting analogue comprising the first 29 amino acids of endogenous GHRH — the minimal sequence required for full GHRHR activation. Requires frequent dosing (once or twice daily) but mimics the physiological GHRH signal closely, making it useful for research requiring near-endogenous GH axis stimulation.

Tesamorelin

The only GHRH analogue to achieve FDA approval (for a specific indication); Phase 3 trial data documented significant visceral fat reduction in HIV patients on antiretroviral therapy with lipodystrophy. Has been investigated in other populations for its metabolic profile.

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