The answer so far
DAC is an added chemical group designed to make the original CJC-1295 stay in the blood longer. “No DAC” and “modified GRF” are used for related material without it. The familiar human half-life estimate comes from the long-acting DAC preparation; it cannot simply be applied to another product.1234
On this page
What do the names mean?
The original long-acting CJC-1295 was designed with an added chemical group called a drug affinity complex, or DAC. A related form without that group is often sold as “CJC-1295 no DAC” or “modified GRF (1–29)”. FDA documents describe separate substances and note inconsistent naming. Treat these terms as a starting question about identity, not proof of the contents of a particular vial.245
Why add a DAC?
The added group was designed to bind albumin, a protein naturally present in blood, and help the peptide remain in circulation longer. Early developer-affiliated experiments studied cell preparations and rats. The idea is about exposure over time, not a claim that longer exposure is automatically better, safer or more useful for muscle or sleep.21
What does the famous half-life number apply to?
In two small 2006 placebo-controlled studies in healthy adults, researchers tested the long-acting DAC preparation and measured blood concentrations, growth hormone and IGF-1, another growth-related signal. Their estimated CJC-1295 half-life was about 5.8–8.1 days. Half-life describes how quickly a measured concentration falls; it is not the time until all effects stop. That estimate belongs to the studied preparation and people, not automatically to a no-DAC product or an online vial. The developer supported the research.14
- DACAn added group designed to bind albumin and extend circulation.
- No DAC / modified GRFA related substance without that group; seller naming can vary.
- 2006: half-lifeSmall healthy-adult studies measured the long-acting DAC preparation.
- 2006: hormone pulsesTwelve men: pulses persisted and between-pulse levels rose; no direct no-DAC comparison.
What about “GH bleed” and normal hormone pulses?
Growth hormone is naturally released in bursts, or pulses. Some online discussions use “GH bleed” to suggest the long-acting form eliminates those pulses. A separate small 2006 study measured overnight blood samples in 12 healthy men before and one week after long-acting CJC-1295. It reported that pulses persisted, while average levels between pulses rose. This was not a direct comparison with no-DAC material and did not establish better sleep, body composition or long-term safety.34
Does no DAC mean the same thing as ipamorelin?
No. The name no DAC refers to a CJC-related substance without the added affinity group. Ipamorelin is a different peptide acting through another receptor involved in growth-hormone release. People discuss using them together because the signals differ; that rationale does not establish the benefits or safety of the combination. Compare CJC-1295 with ipamorelin and what their separate human studies measured.56
Can a seller label or certificate settle what is in a vial?
A name, a claimed purity percentage or a certificate alone does not establish the identity, strength, sterility or stability of the finished product. A certificate may describe only one sample or ingredient and particular tests. The FDA noted inconsistent names and gaps in characterisation for forms considered in its 2024 review. Ask a qualified pharmacist about an actual prescribed or compounded product; a research label does not turn a vial into an approved medicine. Understand product quality and storage claims.45
Which one is better or safer?
The studies described here do not establish that one form is better for strength, fat loss, recovery or sleep, or provide a reliable head-to-head long-term safety comparison. Limited evidence is not proof that either form is harmless or harmful in a particular person. For what was actually reported in the short human studies and the regulator’s concerns, return to the CJC-1295 overview; for the broader claims, explore growth-hormone peptides, muscle, fat and sleep.14
Sources, kept close.
Selected supporting sources; this is not a complete literature review.
- Prolonged stimulation of growth hormone and insulin-like growth factor I secretion by CJC-1295 in healthy adultsJournal of Clinical Endocrinology & Metabolism / PubMed · Two randomised double-blind placebo-controlled human hormone studies; 2006
- Human growth hormone-releasing factor–albumin bioconjugates: identification of CJC-1295Endocrinology / PubMed · 2005 developer-affiliated preclinical cell and rat study
- Pulsatile secretion of growth hormone persists during continuous stimulation by CJC-1295Journal of Clinical Endocrinology & Metabolism / PubMed · 2006 small human hormone study
- Pharmacy Compounding Advisory Committee: CJC-1295 substances and evidenceU.S. Food and Drug Administration · 2024 US regulator advisory slides
- Pharmacy Compounding Advisory Committee: CJC-1295U.S. Food and Drug Administration · Regulator briefing document
- Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patientsInternational Journal of Colorectal Disease / PubMed · Randomised double-blind placebo-controlled phase 2 trial; 2014