CJC-1295 no DAC

The body does not release growth hormone evenly but in bursts. This pulsatility is at the heart of research with CJC-1295 without DAC, which the literature mostly calls Mod-GRF (1-29) or Modified GRF.

The molecule is a shortened analogue of natural GHRH, altered at individual amino acids. The changes make it more resistant to enzymatic breakdown. What it lacks is the maleimide group of the DAC variant, which attaches covalently to albumin. Without that anchor, the half-life stays at roughly 30 minutes.

How it acts in the model:

• binding to GHRH receptors in the anterior pituitary
• acute, amount-dependent release of growth hormone
• a rapid decline afterwards, with the natural feedback left intact

The comparison with its relatives explains the classification. Sermorelin (GHRH 1-29) is quickly cut apart in plasma by the enzyme DPP-IV; in Mod-GRF the altered position 2 guards against exactly that cut, so the effective duration rises without losing the pulse character. CJC-1295 with DAC, in turn, keeps the GHRH stimulus constant for days. Mod-GRF sits in between: more stable than sermorelin, yet short enough to trigger a single pulse. In preclinical studies this pulse-like mode is regarded as the more physiologically relevant one.

In experimental series Mod-GRF is frequently combined with ipamorelin, a secretagogue acting on a different receptor, to examine how the two signals interact on GH pulses. Whenever you read the two names side by side, it is almost always about exactly that question.

As a GHRH analogue the peptide prompts the body's own release rather than supplying growth hormone. The feedback of the axis is thereby preserved, and the short half-life limits every effect in time. Long-term human data are missing; the assessment rests on short studies and anecdotal reports.

• Injection site: redness, a feeling of pressure or a brief irritation after subcutaneous administration, the most frequent observation.
• Typical of growth hormone: water retention that passes, plus numb or tingling hands resembling carpal tunnel syndrome, usually amount-dependent and reversible.
• Glucose metabolism: a raised GH level can lift fasting blood sugar and temporarily lower sensitivity to insulin in studies.
• Tiredness or grogginess shortly after administration, in line with the GH peak.

This summary is no substitute for medical advice.

• Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma - native GHRH is cleaved in plasma mainly by DPP-IV between positions 2 and 3; a D-amino acid at position 1 or 2 prevents this, the rationale behind Mod-GRF.
• Incorporation of D-Ala2 in growth hormone-releasing hormone-(1-29)-NH2 increases the half-life and decreases metabolic clearance in normal men - in ten healthy men the D-Ala2 substitution extended the half-life from 4.3 to 6.7 minutes and lowered clearance.
• Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog - even under continuous stimulation by the DAC variant, pulse-like GH release persisted in healthy men; mainly trough values and IGF-1 were raised.