CJC-1295, Sermorelin, Tesamorelin — comparing the GHRH family

Hypothalamic GHRH binds the GHRH receptor on anterior pituitary somatotropes and triggers pulsatile growth-hormone release. Endogenous pulses are short, episodic, and superimposed on a tonic somatostatin (GHIH) suppression — the somatotrope axis is regulated by the ratio of these two opposing inputs, not by either alone.

Any synthetic GHRH analog is, in principle, a tool for asking what happens when you reinforce the 'go' signal without altering the 'stop' signal. The three analogs below represent three different strategies for doing that.

Sermorelin is GHRH(1-29)-NH₂ — the smallest fragment of native GHRH that retains full agonist activity at the GHRH receptor. Identified in the early 1980s, it was the first analog brought into clinical study and was briefly approved (as Geref) for paediatric growth-hormone deficiency before being withdrawn for commercial reasons.

Half-life in plasma is short — typically reported under 10 minutes — which mirrors endogenous GHRH and preserves pulsatile downstream GH release in animal-model work. For a researcher trying to probe somatotrope dynamics without flattening the pulse, Sermorelin's short kinetics are an asset.

Tesamorelin is human GHRH(1-44) with a trans-3-hexenoic-acid (Hex) group attached at the N-terminus. The modification slows degradation by dipeptidyl peptidase-IV and extends plasma half-life to roughly 30 minutes. It is approved (Egrifta / Egrifta SV) for reducing excess visceral adipose tissue in HIV-associated lipodystrophy — the only FDA-approved GHRH analog at the time of writing.

In research contexts, Tesamorelin is the most-studied GHRH analog for visceral fat and metabolic endpoints. Its longer plasma residence relative to Sermorelin lets it sustain GH release for longer per dose, which matters in models where IGF-1 dynamics are the endpoint.

CJC-1295 is GHRH(1-29) with four amino-acid substitutions (D-Ala²-Gln⁸-Ala¹⁵-Leu²⁷) that stabilise the peptide against enzymatic degradation. There are two forms in the research literature: 'CJC-1295' (without DAC) and 'CJC-1295 with DAC' (DAC = Drug Affinity Complex, a maleimidopropionic-acid moiety that covalently couples to a cysteine residue on serum albumin).

The DAC variant has a reported half-life of several days because once it's bound to albumin it circulates with the carrier protein. Without DAC, CJC-1295 has a half-life closer to 30 minutes — comparable to Tesamorelin.

Practically: 'CJC-1295' without further specification is ambiguous in the literature. When designing an experiment, confirm whether the source material is the DAC or non-DAC variant — the pharmacokinetics are completely different.

Need a short, physiologic GHRH pulse for a single experimental window? Sermorelin.

Studying visceral-fat or sustained-IGF-1 endpoints with a per-dose schedule? Tesamorelin.

Need multi-day exposure with a single injection (long-duration metabolic studies, sleep-architecture work)? CJC-1295-DAC.

All three are typically reconstituted in bacteriostatic water and stored at 2–8°C in solution.