# CJC-1295 Ipamorelin and Mod GRF (1-29), the No-DAC Form > CJC-1295 Ipamorelin and Mod GRF (1-29): the no-DAC, short-acting GHRH fragment that pairs with ipamorelin for a matched-pulse synergy. Half-life, mechanism, and how it differs from DAC, cited. The short, pulsatile GHRH fragment — the version that time-matches ipamorelin's pulse, and the version closest to the studied synergy. ## The short version In a **CJC-1295 Ipamorelin** stack, Mod GRF (1-29) is one of two ways to supply the CJC-1295 half — the short, no-DAC way. "No-DAC" means it skips the chemical hook that the long-acting version uses to grab a blood protein. Without that hook, an enzyme clears it in about half an hour, so it works like a single quick burst rather than a days-long background. That brevity is the point: it lines up in time with ipamorelin's short pulse, which is closer to the kind of paired-pulse signal the human synergy studies actually measured. This page covers what Mod GRF (1-29) is, how it differs from the DAC form, and why the no-DAC route is the better mechanistic match for the stack — no dosing, just the difference. ## What Mod GRF (1-29) is Mod GRF (1-29) is the common name for CJC-1295 *without* DAC: a 29-amino-acid modified fragment of GHRH that retains the receptor-activating business end but carries no albumin-binding group. It binds the same GHRH receptor on pituitary somatotrophs as the DAC form, signalling through Gs → cAMP to drive GH release [5] — the chemistry of the *signal* is identical; only the *duration* differs. The "modified" part refers to amino-acid substitutions engineered to resist DPP-IV (the serum enzyme that rapidly cleaves native GHRH). Those substitutions extend it modestly versus raw GHRH(1-29), but without the DAC there is nothing to anchor it in circulation, so it stays short. ## Half-life and the pulsatile signal Mod GRF (1-29) acts on the order of minutes to ~30 minutes — DPP-IV cleavage clears it quickly, and no formal standalone human pharmacokinetic study has been published; research protocols model it at roughly 100–200 µg per injection as a short pulsatile GHRH signal. Contrast the DAC form, which binds albumin via Cys34 and produces a ~6–8 day half-life with GH and IGF-1 elevated for days [5][1]. Why short can be a feature: native GH is released in pulses — typically 5–9 bursts a day, coordinated by GHRH, ghrelin, and somatostatin. Mod GRF (1-29) mimics a single GHRH-driven pulse rather than flattening the rhythm into a sustained background. The trade-off is that its action is brief and must be re-supplied to repeat, where the DAC form persists from one dose. ## Why no-DAC suits the stack The synergy evidence behind pairing a GHRH analogue with ipamorelin was built on *matched short pulses*. In normal men, submaximal GHRP doses combined with GHRH stimulated GH release synergistically through independent mechanisms [3] — a co-timed-pulse experiment. At the receptor level, co-activating the ghrelin and GHRH receptors produced roughly twice the cAMP of GHRH alone [4]. Mod GRF (1-29) reproduces the GHRH side of that as a short pulse that can be co-timed with ipamorelin's short pulse [2] — the configuration closest to what the synergy literature studied. The DAC form, by contrast, supplies a multi-day GHRH background under the ipamorelin pulse [1], which is a different and less-characterized exposure. Neither is a validated protocol — the fixed combination has never been trial-tested — but mechanistically the no-DAC form is the cleaner match to the studied synergy. ## No-DAC vs DAC, restated For the record, the two CJC-1295 forms: - **Mod GRF (1-29) / no-DAC** — ~3367.9 Da; no albumin binding; ~30-minute half-life; short pulsatile action; time-matches ipamorelin. CAS 446262-90-4. - **CJC-1295 with DAC** — ~3647.3 Da; albumin-bound via Cys34; ~6–8 day half-life; multi-day GH/IGF-1 elevation [1][5]. CAS 863288-34-0. Neither is FDA-approved; neither the fragment nor the [cjc 1295 dac](/cjc-1295-dac) form, nor either paired with ipamorelin, has been validated in a controlled human trial of the fixed blend. This page documents the no-DAC pharmacology — not a dose, not a recommendation. --- Two receptors logged on one onyx panel — the supra-additive GH crest read off single-peptide data and the general synergy work, the fixed blend's missing trial left as an empty cell; no clinic behind the console and nothing here dosed, stacked, or sold.