Here's the trap that catches almost everyone: "CJC-1295" refers to two different molecules, and they behave nothing alike. The difference is a single small add-on called DAC. Get this straight first and everything else about CJC-1295 falls into place.
In plain terms: it's the same peptide with or without a tiny anchor — and that anchor changes whether it lasts minutes or days.
What DAC does
DAC — Drug Affinity Complex — is a small chemical group that grabs onto albumin, one of the most abundant, long-lasting proteins in your blood. A peptide hitched to albumin is shielded from the enzymes that would otherwise chew it up quickly, so it circulates far longer.
| No-DAC (mod GRF 1-29) | With DAC | |
|---|---|---|
| Albumin anchor | No | Yes |
| Reported half-life | Minutes | Days (~6–8) |
| Presence in the body | Brief pulse | Sustained, multi-day |
| Base peptide | GHRH(1-29) analog | Same GHRH(1-29) analog |
What the studies actually found
The DAC form is unusually well-measured for a research peptide — it has genuine human pharmacokinetic data:
| Study | Model | Key result | Year |
|---|---|---|---|
| GHRH(1-29) baseline3 | Human (sermorelin, the un-anchored fragment) | The plain GHRH(1-29) sequence is short-acting — cleared in minutes | 1999 |
| Teichman et al.1 | Human (CJC-1295 DAC) | A single injection kept growth hormone up 6+ days and IGF-1 up 9–11 days; measured half-life 5.8–8.1 days | 2006 |
| Ionescu & Frohman2 | Human (CJC-1295 DAC) | Even under constant DAC stimulation, growth hormone kept its natural pulses; trough levels rose ~7.5× | 2006 |
In plain terms: strip off the anchor and you have sermorelin-like behavior — a quick pulse gone in minutes. Add the anchor and one injection works for the better part of a week. That's the entire DAC story, and it's backed by real human measurements.
Why this changes the schedule
A minutes-long half-life (no-DAC) means the compound arrives as a brief pulse, so no-DAC research protocols reflect that short window. The DAC form's multi-day half-life produces a sustained presence instead1. Same base peptide, completely different level curve — which is exactly what a half-life governs.
"Mod GRF 1-29"
The no-DAC version is usually called mod GRF 1-29 — modified GRF, the 1–29 amino-acid GHRH fragment. It's the short-acting counterpart to DAC CJC-1295, and closely related to plain sermorelin.
The practical bottom line
When any source cites a "CJC-1295 half-life," the DAC-versus-no-DAC distinction decides whether they mean minutes or days — always pin that down first, because a figure without the form attached is meaningless. Both remain research compounds, not approved medicines. More context in what is CJC-1295 and CJC-1295 vs ipamorelin.