RESEARCH REVIEW / GHRH-ANALOG PHARMACOKINETICS
CJC-1295 is a long-acting GHRH analog — here is what the human pharmacokinetics actually show.
A state-by-state read of the published record: what the human data confirm, where the DAC and no-DAC stories diverge, and where the forum claims outrun the evidence — every figure logged to its study.
The one-line state of CJC-1295
CJC-1295 is a synthetic analog of growth-hormone-releasing hormone (GHRH), built on the first 29 residues of human GH-releasing factor — hGRF(1-29) — with four amino-acid substitutions that block enzymatic breakdown. In its DAC form it binds covalently to serum albumin, which stretches its plasma half-life to an estimated 5.8-8.1 days [1]. That is the entire compound in a sentence, and almost every confusion about it traces back to two variants being treated as one.
The DAC variant is long-acting. A single subcutaneous dose raised mean plasma growth hormone 2- to 10-fold for six days or more and kept IGF-1 above baseline for nine to eleven days; after multiple doses, IGF-1 stayed elevated for up to 28 days [1]. The no-DAC form — sold as "Modified GRF 1-29" — keeps the four substitutions but drops the albumin handle, so it clears in minutes to hours [9][8]. Same backbone, two completely different clocks. This site reads the record one state at a time: what is confirmed, what is preclinical-only, what is a regulatory note, and what is simply a gap.
The sections below link out to what the human research shows, the pharmacokinetics and half-life lens, and the DAC vs no-DAC (Modified GRF 1-29) disambiguation. Every quantitative claim resolves to the full reference list.
What is CJC-1295?
CJC-1295 is a long-acting GHRH analog — a peptide that acts upstream on the pituitary rather than a hormone you replace directly. It binds the GHRH receptor on anterior-pituitary somatotrophs and triggers the cell's own machinery to synthesize and release growth hormone, which then raises hepatic IGF-1 [3].
What is CJC-1295?
A synthetic analog of growth-hormone-releasing hormone built on hGRF(1-29) with four protease-resistant substitutions. The DAC variant is covalently bound to serum albumin for a multi-day half-life; the no-DAC form ("Modified GRF 1-29") is short-acting. The four substitutions — D-Ala at position 2, Gln at 8, Ala at 15, Leu at 27 — stabilize the helix and resist the enzymes that shred native GHRH [7][8].
What does CJC-1295 do?
It is a long-acting GHRH analog: it binds the GHRH receptor on pituitary somatotrophs and stimulates pulsatile growth-hormone release, which raises hepatic IGF-1. In healthy men a single dose raised mean GH approximately 46% and IGF-1 approximately 45% one week later, while the natural pulse pattern of GH secretion was preserved [3].
CJC-1295 as a synthetic GHRH-analog peptide
CJC-1295 is a peptide, not a steroid. Structurally it is a tetrasubstituted hGRF(1-29) — a short chain of amino acids that mimics the body's own growth-hormone-releasing signal — with a molecular weight near 3,367.9 Da before albumin conjugation [2]. It does not touch the androgen axis; its only documented mechanism is GHRH-receptor activation on the pituitary.
That distinction matters for reading the literature. Because CJC-1295 works by amplifying the body's own GH pulses rather than supplying growth hormone directly, the published studies track GH and IGF-1 as their readouts [1][3]. The four protease-resistant substitutions are what separate it from native GHRH(1-29), which dipeptidylpeptidase-IV degrades within minutes [8]. In the DAC variant, an added maleimidopropionyl-lysine handle bonds to a free thiol on circulating albumin, and that single chemistry is the difference between a drug that lasts minutes and one that lasts days [2].
How the evidence actually stacks up
The confirmed state is narrow and real. In rats, the albumin conjugate produced roughly 4-fold higher GH exposure over two hours than the unconjugated peptide and remained detectable in plasma beyond 72 hours [2]. In healthy adults, the human PK is well characterized for single and multiple doses [1][3]. In GHRH-knockout mice, once-daily dosing fully normalized growth [4]. None of that is in dispute.
The gap state is just as real, and this site keeps it in plain view. There is no long-term human safety trial. The original long-acting DAC program (ConjuChem) ran a Phase 2 study in HIV-associated visceral obesity and was discontinued; the program did not advance [1]. Most dosing "protocols" circulating online are not derived from controlled human trials. And the regulatory state is unambiguous: CJC-1295 is not approved for human use by any major regulator, and at the 2024 FDA Pharmacy Compounding Advisory Committee it was reviewed and not recommended for the 503A compounding bulks list, with immunogenicity among the cited concerns. For how strong the evidence is, the doses used in the studies, the answer to is CJC-1295 FDA approved?, and the side effects and safety questions, follow the links.