Drug affinity complex (DAC)

A drug affinity complex DAC is a chemical add-on that attaches a peptide to albumin, the abundant protein circulating in blood, so the peptide stays in circulation far longer. In CJC-1295, DAC stretches a measured human half-life from the usual peptide timescale to 5.8–8.1 days.

What does DAC mean in a peptide?

DAC means drug affinity complex: a peptide, a short linker, and a reactive chemical group designed to attach to albumin after injection. Think of the peptide as a small boat and albumin as a cargo ship. The DAC is the coupling that lets the small boat travel with the ship instead of being cleared on its own.

For CJC-1295, the reactive end is a maleimide group. The group forms a covalent bond—a durable chemical bond—with the free sulfur-containing site on cysteine 34 of serum albumin. In the human CJC-1295 study, at least 90% of the compound bound to albumin this way. The peptide remains able to activate its growth-hormone-releasing hormone (GHRH) receptor while attached; albumin is a carrier, not an off switch.

That mechanism is specific. A drug affinity complex DAC does not mean “anything that makes a drug last longer,” and it is not the same as ordinary drug affinity, which describes how strongly a drug binds its target.

How does albumin binding make CJC-1295 last days?

Albumin binding makes CJC-1295 harder for enzymes to cut apart and slower for the kidneys to remove. The result is a longer half-life—the time required for the amount circulating in blood to fall by half. The human number belongs to the DAC form: 5.8–8.1 days after subcutaneous injection.

The contrast is large. Native GHRH has a reported half-life of about seven minutes. The albumin-bound CJC-1295 concentration remained measurable for roughly 10–14 days in the human trial, while growth hormone and insulin-like growth factor 1 (IGF-1) stayed elevated for days. Those findings show that the chemical handle changes exposure, not that the compound has been proved to build muscle or improve recovery.

The albumin mechanism began with preclinical evidence. Researchers found CJC-1295 on the serum-albumin band in rat blood within 15 minutes, and the signal remained beyond 24 hours. A later randomized study in healthy adults supplied the human half-life figure. Mechanism and human pharmacokinetics are separate evidence rungs; here, both point the same way.

CJC-1295 with DAC vs without: are they the same?

CJC-1295 with DAC and CJC-1295 without DAC are not interchangeable names for one finished compound. The DAC form carries the albumin-binding chemical handle. The product called CJC-1295 no DAC usually refers to Modified GRF 1-29, the short-acting tetrasubstituted GHRH fragment without that handle.

This naming mess matters because many pages quote a neat “days versus 30 minutes” comparison as settled human pharmacokinetics. The days side is supported: CJC-1295 with DAC has a measured 5.8–8.1-day half-life in healthy adults. The no-DAC side is much thinner. No peer-reviewed human study has established an exact half-life for Modified GRF 1-29, and its profile therefore reports the honest scale—minutes—without pretending a precise number was measured.

FDA’s review is even blunter: CJC-1295 DAC and the forms without DAC are distinct active moieties, and the pharmacological profile of the DAC form cannot simply be carried over to the no-DAC form. FDA also noted that a direct comparison would be needed to prove how much of the stability difference comes from DAC rather than the four stabilizing amino-acid substitutions in the shared peptide core.

What is the DAC:GRF meaning?

DAC:GRF means drug affinity complex–growth hormone-releasing factor, an older research name for the albumin-binding form of CJC-1295. GRF and GHRH refer to the same natural signal: growth hormone-releasing factor, now more commonly called growth hormone-releasing hormone. The colon joins the delivery chemistry to the active peptide; it does not name a peptide stack.

This is also the clean answer to “what does DAC mean peptide?” DAC describes the albumin-binding extension technology. GRF describes the hormone fragment doing the receptor work. In CJC-1295, one part keeps the compound circulating and the other tells the pituitary to release more of the body’s own growth hormone.

What does the evidence actually prove?

The evidence proves albumin binding in preclinical work and prolonged exposure plus sustained hormone changes in healthy adults; it does not prove bodybuilding, fat-loss, recovery, or anti-aging outcomes. The distinction is easy to lose because a long half-life sounds like a long list of benefits. Chemistry can establish duration without establishing a useful clinical result.

• Mechanism evidence: the 2005 Jetté study showed albumin bioconjugation and extended circulation in rats. That is preclinical evidence, not a human outcome trial.
• Human pharmacokinetics: the 2006 Teichman randomized trials measured the DAC form’s 5.8–8.1-day half-life and sustained GH and IGF-1 increases in healthy adults.
• No-DAC gap: direct human pharmacokinetic data for Modified GRF 1-29 are absent. “Short-acting” is supported by the compound’s design and related biology; a precise human half-life is not.

The last point is the useful one most commercial explainers skip. A tidy number is not automatically a measured number.

Does DAC make CJC-1295 FDA-approved?

DAC does not make CJC-1295 an FDA-approved drug. FDA’s review covers five distinct CJC-1295 forms, including DAC and non-DAC versions, and states that none is a component of an FDA-approved drug. The agency also concluded that the evidence weighed against adding those forms to the 503A compounding bulks list.

As of April 2026, FDA’s current compounding-risk page lists CJC-1295 among withdrawn nominations that may present significant safety risks, citing limited clinical data, immune-reaction and impurity concerns, increased heart rate, and a systemic vasodilatory reaction. That regulatory reality does not erase the albumin mechanism or the human hormone findings. It keeps a chemistry fact, an early human pharmacology result, and an approved medicine from being blurred into one claim.