CJC-1295 Half-Life: How Long It Stays Active
Hormonal, Growth Hormone & Body Composition Research
CJC-1295 with DAC has a published human half-life of 5.8 to 8.1 days after subcutaneous injection in healthy adults (Teichman et al., J Clin Endocrinol Metab, 2006), while CJC-1295 without DAC, also called modified GRF (1-29), lacks the albumin-binding group and belongs to the minutes-scale family of its parent hormone, whose human half-life is 6.8 minutes. The difference comes down to one chemical add-on, the drug affinity complex (DAC), that lets the peptide ride on albumin in the blood. Vistara Labs supplies the no-DAC form, blended with ipamorelin, as the CJC-1295 + Ipamorelin (No DAC) vial and the ready-mixed CJC-1295 + Ipamorelin Nasal Spray.
Findings
- In two randomised, placebo-controlled trials in healthy adults aged 21 to 61, CJC-1295 with DAC had an estimated half-life of 5.8 to 8.1 days (Teichman et al., 2006).
- A single injection raised mean growth hormone 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days; with repeated doses IGF-1 stayed above baseline for up to 28 days.
- One week after a single injection, growth hormone pulses were preserved, trough levels were 7.5-fold higher and IGF-1 was up 45% (Ionescu and Frohman, 2006).
- The DAC group bonds the peptide to albumin; in rats CJC-1295 was still present in plasma beyond 72 hours (Jetté et al., 2005).
- Without DAC, the parent hormone GHRH lasted 6.8 minutes in human blood and GRF (1-29) about 10 minutes in rats (Frohman et al., 1986; Rafferty et al., 1985).
View product →What does half-life mean?
Elimination half-life is the time it takes for a compound’s concentration in the blood to fall by half. After one half-life half remains, after two a quarter, after four about one-sixteenth. For CJC-1295 the term covers two very different molecules sold under one name, so the first question for any figure is which form it describes. The background to that split is in CJC-1295 With or Without DAC: Why It Matters.
Two forms of CJC-1295
Both forms start from GRF (1-29), the first 29 amino acids of human growth hormone-releasing hormone (GHRH), the hypothalamic signal that tells the pituitary to release growth hormone. The developers described CJC-1295 as a tetrasubstituted GRF (1-29): four amino acids are swapped, including a D-alanine at position 2, and a lysine carrying a reactive maleimide group is added at the end (Jetté et al., Endocrinology, 2005). That reactive group is the DAC.
- With DAC (the compound named CJC-1295 in the clinical papers): the maleimide group forms a bond with a free thiol on albumin, the most abundant protein in blood, after injection.
- Without DAC (modified GRF 1-29): the same four substitutions, without the albumin-binding lysine. It is the form in our CJC-1295 + Ipamorelin products.
Why the DAC form lasts about a week
Albumin is a large, long-lived blood protein, and fixing a peptide to it is an established way to extend plasma half-life (Jetté et al., 2005). In the original rat studies, an albumin-bound CJC-1295 band appeared on blood analysis within 15 minutes of injection and remained beyond 24 hours, and the peptide was still measurable in plasma beyond 72 hours (Jetté et al., 2005). In humans, the two Teichman trials put the half-life at 5.8 to 8.1 days, with growth hormone raised for at least 6 days and IGF-1 for 9 to 11 days after a single injection; no serious adverse reactions were reported (Teichman et al., 2006).
A follow-up study sampled growth hormone every 20 minutes overnight in healthy men aged 20 to 40, before and one week after a single injection. Pulse frequency and size were unchanged, but trough levels rose 7.5-fold, mean growth hormone rose 46% and IGF-1 rose 45%, showing that steady background stimulation raised output while the pituitary kept its own rhythm (Ionescu and Frohman, J Clin Endocrinol Metab, 2006).
Why the no-DAC form is measured in minutes
Natural GHRH is destroyed quickly by dipeptidyl peptidase-4 (DPP-4), a plasma enzyme that removes its first two amino acids and leaves a product with less than one-thousandth of the activity. After intravenous injection in healthy people, intact GHRH had a half-life of 6.8 minutes (Frohman et al., J Clin Invest, 1986). In anaesthetised rats, GRF (1-29) given intravenously had an elimination half-life of 10.4 minutes (Rafferty et al., J Endocrinol, 1985).
A D-amino acid at position 1 or 2 blocks that DPP-4 cut (Frohman et al., J Clin Invest, 1989), which is why the substitutions in modified GRF (1-29) make it sturdier than the natural sequence. Without albumin binding, though, it is still small enough to be cleared by the kidneys and by other plasma enzymes. We could not find a peer-reviewed human half-life for modified GRF (1-29) on its own, so this page does not quote one; the published reference points for its family are the minute-scale figures above.
How does CJC-1295 compare with related compounds?
| Compound | Published half-life | Species and route |
|---|---|---|
| CJC-1295 with DAC | 5.8 to 8.1 days | Humans (SC) |
| Natural GHRH | 6.8 min | Humans (IV) |
| GRF (1-29) | 10.4 min | Rats (IV) |
| Tesamorelin | 8 to 38 min | Humans (SC, FDA labels) |
| Ipamorelin | About 2 h | Humans (IV infusion) |
Tesamorelin, another GHRH analogue, is protected at its starting end but does not bind albumin, and the labels give half-lives of 8 to 38 minutes; see Tesamorelin Half-Life. Ipamorelin, the partner peptide in our blend, acts on a different receptor and lasts about 2 hours in humans (Gobburu et al., Pharm Res, 1999); see Ipamorelin Half-Life and CJC-1295 vs Ipamorelin.
What does this mean for study design?
- DAC studies run over weeks. With a week-long half-life, the Teichman trials ran for 28 and 49 days, and outcomes were tracked as days of raised growth hormone and IGF-1.
- No-DAC studies run over minutes and hours. A short-lived GHRH signal produces a discrete growth hormone response, so sampling clusters in the hours after administration.
- Pulsatility needs frequent sampling. Overnight draws every 20 minutes separated pulse size from trough levels in the Ionescu study.
- Name the form. Because both molecules circulate under the name CJC-1295, methods sections that state with or without DAC are the only way to compare results.
Human results for the blend are covered in CJC-1295 + Ipamorelin: The Research.
Half-life in the body vs how long a vial or spray keeps
Half-life describes clearance after a peptide enters a living system. How long a vial or spray stays usable is a separate question of chemical stability, which depends on temperature, light, moisture and whether the lyophilised (freeze-dried) powder has been mixed. Those timelines are covered in How Long Does CJC-1295 + Ipamorelin Last? Storage Guide. Vials are reconstituted with bacteriostatic water (see the CJC-1295 + Ipamorelin reconstitution guide); the nasal spray arrives ready-mixed in a sealed metered pump. Every product is third-party tested, with certificates on the lab reports page, and orders ship from within Canada by Canada Post Xpresspost.
CJC-1295 + Ipamorelin is supplied for laboratory research use only. The human figures above come from clinical research using the DAC form of CJC-1295.
Frequently asked questions
What is the half-life of CJC-1295?
CJC-1295 with DAC had an estimated half-life of 5.8 to 8.1 days in healthy adults in two placebo-controlled trials (Teichman et al., 2006). CJC-1295 without DAC lacks albumin binding and belongs to the minutes-scale family of natural GHRH, which lasted 6.8 minutes in human blood.
What is the difference between CJC-1295 with and without DAC?
Both are modified GRF (1-29) with four amino acid substitutions. The DAC version adds a lysine with a reactive group that bonds to albumin in the blood, which extends its half-life to about a week. The no-DAC version, modified GRF (1-29), has no albumin binding.
What did research show about CJC-1295 with DAC and growth hormone?
A single injection raised mean growth hormone 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days. A follow-up study found growth hormone pulses preserved, with trough levels 7.5-fold higher one week after injection.
Which form of CJC-1295 does Vistara Labs supply?
Vistara Labs supplies the no-DAC form, blended with ipamorelin, as the CJC-1295 + Ipamorelin (No DAC) vial and the ready-mixed CJC-1295 + Ipamorelin Nasal Spray.
Is CJC-1295’s half-life the same as how long a vial lasts?
No. Half-life describes clearance from the body. How long a vial or nasal spray keeps depends on storage and whether the powder has been mixed, which is covered in the CJC-1295 + Ipamorelin storage guide.
Product details from vistaralabs.ca, October 2026. Sources: Teichman SL et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006. PMID 16352683. Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006. PMID 17018654. Jetté L et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005. PMID 15817669. Frohman LA et al. Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive product cleaved at the NH2 terminus. J Clin Invest. 1986. PMID 3093533. Frohman LA et al. Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma. J Clin Invest. 1989. PMID 2565342. Rafferty B et al. Growth hormone-releasing factor analogue (hGRF1-29NH2): immunoreactive-GRF plasma levels after intravenous and subcutaneous administration. J Endocrinol. 1985. PMID 2866222. Gobburu JV et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999. PMID 10496658. EGRIFTA (tesamorelin) prescribing information, US FDA, 2010. FDA label.
More on this: Buy CJC-1295 + Ipamorelin in Canada.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
References
The published human CJC-1295 trial used the long-acting DAC analogue, not the no-DAC form. Ipamorelin has its own human pharmacokinetic study. No trial of the two combined was identified.
- Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adultsRandomised placebo-controlled trial in healthy adults — of the LONG-ACTING (DAC) CJC-1295 analogue, not the no-DAC form.
- Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteersHuman pharmacokinetic/pharmacodynamic study; five escalating infusion levels, eight healthy male subjects per level.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
