GHRH Analogs Explained: CJC-1295 vs Tesamorelin

GHRH is a 44-amino-acid hypothalamic hormone cleaved by DPP-IV within minutes. Tesamorelin keeps the full sequence and caps the N-terminus with trans-3-hexenoic acid; CJC-1295 keeps only residues 1–29 and makes four stabilising substitutions (optionally adding an albumin-binding DAC group). Tesamorelin has the larger clinical literature; CJC-1295's two 2006 J Clin Endocrinol Metab papers are its defining references.

What GHRH does

Growth-hormone-releasing hormone is released by the hypothalamus and acts on the pituitary to trigger growth-hormone secretion, which in turn drives IGF-1 production in the liver. Native GHRH(1-44) is cleaved between residues 2 and 3 by the enzyme DPP-IV, giving it a half-life of minutes. The first 29 residues carry the receptor activity, which is why many analogs are 1-29 fragments.

Two engineering strategies

Tesamorelin takes the full 44-residue sequence and adds a trans-3-hexenoic acid group to the N-terminus, blocking the DPP-IV cleavage site. Otherwise it is native human GHRH. Because a pharmaceutical formulation was developed for a specific HIV-related indication, it has an extensive clinical literature: visceral adipose tissue and liver enzymes [1], fat quality [2], muscle composition [3], hepatic fibrosis proteomics [4], and use with integrase inhibitors [5].

CJC-1295 takes only residues 1–29 and makes four amino-acid substitutions (at positions 2, 8, 15 and 27) that protect against DPP-IV and other proteases. The original compound also carried a drug-affinity complex (DAC) — a reactive group that binds covalently to serum albumin, extending residence in circulation to days; the variant without it is often called Mod GRF 1-29. The defining references are two 2006 papers: one characterising prolonged GH and IGF-1 stimulation [6], the other reporting that GH secretion stayed pulsatile under continuous stimulation [7].

Research comparison

• Sequence length: 44 · 29
• Stability strategy: N-terminal cap · residue substitutions (+ optional DAC)
• Literature depth: extensive clinical · two pivotal clinical-pharmacology studies
• Studied endpoints: visceral fat, liver markers, muscle composition · GH/IGF-1 secretion profile and pulsatility
• Molecular weight: 5135.9 · 3367.9 g/mol
• Format: tesamorelin 10 mg vial, $99 · CJC-1295 5 mg vial, $50

Which do laboratories choose?

A lab reproducing or extending the clinical literature reaches for tesamorelin because the published work uses it. A lab studying GH-axis pharmacology with a long-acting, albumin-bound stimulus reaches for CJC-1295 with DAC; one wanting a shorter, more pulsatile stimulus reaches for the non-DAC form. The COA states which form a CJC-1295 lot is.

Clinical and laboratory findings described here concern the drug class and pharmaceutical studies, not the research-grade material sold by APX Labs, which is not a drug and is for research use only.

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