CJC-1295 vs MK-677
Research Comparison

Research Overview

CJC-1295 vs MK-677 compares two ways of making the pituitary release growth hormone (GH) through different receptors. CJC-1295 is a substituted analog of growth hormone-releasing hormone (GHRH) residues 1 to 29, and albumin conjugates of its DAC form activated the GHRH (GRF) receptor in rats (Jetté et al., 2005). MK-677 (ibutamoren) is an orally active non-peptide that acted like the GH-releasing peptide GHRP-6, not GHRH, in rat pituitary cells (Patchett et al., 1995) and binds the human ghrelin receptor (Liu et al., 2021).

The human CJC-1295 studies cited here used the form with a drug affinity complex (DAC), and a 2026 review found no peer-reviewed human studies of the No DAC form (Dominikowski et al., 2026). Disguised Alpha supplies CJC-1295 No DAC (lyophilized, 10MG vial), a 5MG/5MG No DAC and ipamorelin blend and MK-677 (10MG capsules, 60 per bottle), and lists CJC-1295 with DAC (5MG vial), for laboratory research use only. Nothing on this page is guidance for use in people.

Structure and Class

CJC-1295 No DAC is Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2: GHRH(1-29) amide with D-Ala2, Gln8, Ala15 and Leu27 (PubChem CID 56841945; 3367.9 g/mol on its product page). The named compound adds a C-terminal lysine carrying a 3-maleimidopropionamide group, placed to bond the free thiol on cysteine 34 of serum albumin (Jetté et al., 2005); its product page lists 3647.06 g/mol (PubChem CID 91971820 computes 3647.2).

MK-677 is a spiroindoline sulfonamide (Jacks et al., 1996): a methanesulfonyl spiro(indoline-3,4'-piperidine) joined to O-benzyl-D-serine and 2-aminoisobutyric acid. Its product page lists C27H36N4O5S, 528.7 g/mol, the ibutamoren free base (PubChem CID 178024); the hip fracture trial named the mesylate salt (Adunsky et al., 2011), 624.8 g/mol (CID 6450830).

Side by Side

Research Context: CJC-1295

In the founding study, albumin conjugates of three maleimido GHRH(1-29) derivatives were more stable against dipeptidylpeptidase-IV in vitro and released GH from cultured rat pituitary cells. Given subcutaneously to rats, CJC-1295 gave four times the two-hour GH area under the curve of GHRH(1-29) and persisted in plasma beyond 72 hours (Jetté et al., 2005). Models: rat cells and rats.

In two randomized, placebo-controlled trials with ascending amounts in healthy adults aged 21 to 61, one subcutaneous exposure raised mean GH two to tenfold for six days or more and IGF-I 1.5 to threefold for 9 to 11 days, depending on the amount; the estimated half-life was 5.8 to 8.1 days, and no serious adverse reactions were reported (Teichman et al., 2006).

In healthy men aged 20 to 40 sampled overnight before and a week after one exposure, GH pulse frequency and magnitude were unaltered while trough GH rose 7.5 fold (Ionescu and Frohman, 2006). Both used the DAC form; both abstracts report no hormones besides GH and IGF-I.

For No DAC, a 2026 review found no peer-reviewed human studies and no reported human half-life, traced claims about it mainly to the 1-29 fragment sermorelin, placed it in evidence tier D against tier B for the DAC form, and states that neither form is approved by the FDA or the EMA (Dominikowski et al., 2026).

The DAC figures above do not apply to it. An FDA page lists CJC-1295 among bulk substances previously in category 2 whose nominations were withdrawn, citing possible immunogenicity, serious adverse events including increased heart rate and systemic vasodilatory reaction, and limited clinical data.

Research Context: MK-677

Merck's L-163,191 (MK-0677) released GH from rat pituitary cells with an EC50 of 1.3 nM and, given orally to dogs, left aldosterone, LH, thyroxine and prolactin without significant change, with only modest cortisol increases (Patchett et al., 1995). In beagles, one oral exposure kept GH elevated up to 360 minutes, a duration the authors contrasted with GHRP-6 (Jacks et al., 1996). Models: rat cells and dogs.

As research history: in a placebo-controlled trial in 32 healthy adults aged 64 to 81, two weeks at the highest of three daily oral amounts raised mean 24-hour GH 97% by enhancing existing pulsatile secretion (pulse height and interpulse nadir up, pulse number unchanged); IGF-I reached the young-adult range, fasting glucose rose by four weeks, cortisol did not change, and prolactin rose 23% but stayed within the normal range (Chapman et al., 1996).

A two-year randomized trial in 65 healthy adults aged 60 to 81 raised GH and IGF-I to young-adult levels, with fasting glucose and cortisol up, insulin sensitivity down, and increased appetite, transient mild leg swelling and muscle pain the most frequent side effects (Nass et al., 2008).

A phase IIb trial in 123 older adults after hip fracture was terminated early due to a safety signal of congestive heart failure in a limited number of participants (Adunsky et al., 2011), and the FDA page places ibutamoren mesylate in category 2 under 503A and 503B, citing the potential for congestive heart failure in certain patients. In rats, the GH response to oral MK-677 was abolished at six weeks and hypothalamic somatostatin expression was markedly increased; the authors called this desensitization (Lee et al., 2018).

Choosing Between Them for a Research Question

Start with the receptor: GHRH receptor signaling has precedent with CJC-1295, and albumin conjugation with its DAC form; ghrelin receptor binding by a non-peptide and oral exposure in animal models, with MK-677. In rat pituitary cells, GRF raised cyclic AMP threefold while GHRP-6 did not, and a GRF antagonist did not block GHRP-6 (Cheng et al., 1989); that split would need confirming for CJC-1295 and MK-677.

Then match sampling to each form's time course. Repeated exposure also differed by model, with evidence of a cumulative effect for the DAC form in healthy adults (Teichman et al., 2006), a lost GH response to MK-677 at six weeks in rats (Lee et al., 2018) and young-adult GH and IGF-I levels in a two-year trial in older adults (Nass et al., 2008). Because the MK-677 papers also report cortisol, prolactin and glucose, a head-to-head design in one species would need that panel for both.

Handling and Storage

All three CJC-1295 product pages list -20°C for the lyophilized powder as shipped and 2 to 8°C after reconstitution, protected from light, with freeze/thaw cycles avoided. Let a sealed vial reach room temperature before opening, add diluent down the wall, swirl gently and aliquot. Keep thiol reagents, albumin and serum out of DAC stock solutions unless conjugation is the experiment, since its maleimide reacts with free thiols.

MK-677 capsules ship sealed, and the product page lists 15 to 25°C in the original container, away from moisture and direct light. Keep each lot's certificate from the COA portal and use measured content where it is reported: the No DAC lot CND02 certificate reports 10.23 mg against a 10 mg label. The MK-677 page lists the free base formula, so check the certificate for the form before molar calculations.

Questions Researchers Ask

CJC-1295 vs MK-677: what is the difference?

CJC-1295 is a GHRH analog peptide of 29 residues, 30 with DAC (Jetté et al., 2005); MK-677 is an orally active non-peptide that acted like GHRP-6, not GHRH, in rat pituitary cells (Patchett et al., 1995) and binds the ghrelin receptor (Liu et al., 2021).

MK-677 vs CJC-1295: which has more human research?

MK-677, on a PubMed count. On 12 October 2026, a search for MK-677, MK-0677 or ibutamoren limited to the publication types Clinical Trial or Randomized Controlled Trial returned 20 records, and the same search for CJC-1295 returned 2, both with the DAC form (Teichman et al., 2006; Ionescu and Frohman, 2006); none covers No DAC.

Have CJC-1295 and MK-677 been studied together?

No experimental study turned up: a PubMed search on 12 October 2026 for CJC-1295 with MK-677 or ibutamoren returned two records, both 2026 reviews. The pairing rationale rests on other compounds: GRF and GHRP-6 at maximal concentrations were synergistic on GH release in rat pituitary cells (Cheng et al., 1989); that is not evidence for this pair.

Are CJC-1295 and MK-677 approved or prohibited in sport?

Neither is an FDA-approved drug: a 2026 review states that neither CJC-1295 form is approved by the FDA or the EMA (Dominikowski et al., 2026), and Drugs@FDA lists no ibutamoren product. The 2026 WADA Prohibited List names CJC-1295 and ibutamoren (MK-677) under S2.2.4, in class S2, which is prohibited at all times.