CJC-1295 vs. Mod-GRF (1-29): What's the Difference?

The difference in one sentence

CJC-1295 carries a so-called DAC group (Drug Affinity Complex) that binds to albumin in the blood and keeps the substance active for days. Mod-GRF (1-29) is the same active backbone without that group – and therefore acts for only about half an hour. Strictly speaking, Mod-GRF (1-29) is the backbone from which CJC-1295 is created by attaching the DAC group.

What they share

Both belong to the class of GHRH analogs. They mimic the body's own growth hormone-releasing hormone (GHRH) and bind to its receptor in the pituitary, where they prompt the release of growth hormone (GH). GH in turn raises levels of the growth factor IGF-1.

• Both are based on GHRH and act indirectly – they do not supply growth hormone but stimulate its release.
• Both are stabilised against rapid enzymatic degradation by DPP-IV.
• Neither is an approved medicine.

The DAC modification: days instead of minutes

DAC stands for Drug Affinity Complex. Specifically, a maleimidopropionic acid group binds covalently to circulating serum albumin – the most abundant protein in blood. As a result, the substance is no longer broken down within minutes but stays in circulation for several days. For CJC-1295 (with DAC), half-lives of roughly six to eight days are described.

Mod-GRF (1-29) lacks this albumin-binding group. Its half-life is therefore only about 30 minutes. This single structural difference accounts for the entire divergent effect profile of the two variants.

Pulse vs. baseline: the practical difference

In the body, growth hormone is normally released in short bursts (pulses), mainly at night. Through its short duration of action, Mod-GRF (1-29) produces an equally short, pulse-like GH rise that more closely resembles this natural pattern. CJC-1295 with DAC, by contrast, keeps GH and IGF-1 levels elevated for days – a sustained raised baseline rather than individual pulses.

This difference – pulsatile versus sustained – is the actual reason the two variants are distinguished in discussions. Which profile carries which consequences, however, has not been conclusively established scientifically.

Evidence and legal status

CJC-1295 has been studied in early clinical trials (Phase I/II) in healthy adults, showing dose-dependent increases in GH and IGF-1 over several days after a single dose. Therapeutic development was not carried through to approval, however – completed Phase III studies are absent. Mod-GRF (1-29) emerged as the backbone prior to DAC conjugation; independent controlled human studies of it are practically absent, and the evidence is preclinical.

Both substances are not approved as medicines in Germany, Austria, Switzerland, the EU or the USA. They are traded exclusively as "research" material; obtaining them for use in humans is legally problematic. As GHRH analogs, they are also relevant in the anti-doping context. Peptica sells nothing and names no sources – the country-specific status is available on the respective peptide pages.