Side-by-side · Research reference

CJC-1295 (no DAC)vsMK-677

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 1Reviewed15/51 cited

BPhase 2Reviewed13/45 cited

CJC-1295 (no DAC)

Short-acting GHRH · No DAC variant

100 mcgPer doseTeichman 2006

~30 minHalf-lifeIonescu 2006

Phase 1Evidence levelTeichman 2006 Sigalos 2018

SQ · Pre-sleep · 1–2×/day

MK-677

Oral GHS · Ibutamoren

10–25 mgDaily dose (oral)Nass 2008

Phase 2Evidence levelMurphy 1998 Nass 2008

~24 hrHalf-lifeNass 2008

Oral capsule · 1×/day

01Mechanism of Action

Parameter

CJC-1295 (no DAC)

MK-677

Primary target

Pituitary GHRH receptorTeichman 2006

Ghrelin receptor (GHS-R1a)Murphy 1998

Pathway

GHRH-R → Gαs → cAMP → PKA → GH vesicle exocytosisTeichman 2006

GHS-R1a → Gαq → Ca²⁺ → sustained GH pulses across 24 hrNass 2008

Downstream effect

Pulsatile GH release matching physiological pattern; subsequent IGF-1 elevationIonescu 2006

Sustained GH + IGF-1 elevation; appetite stimulation; lean mass preservationNass 2008

Feedback intact?

Yes — short pulse preserves somatostatin negative feedbackIonescu 2006

Pulsatile pattern preserved despite long half-lifeMurphy 1998

Origin

Modified human GRF 1-29 with four substitutions (D-Ala²/Gln⁸/Ala¹⁵/Leu²⁷) for protease resistanceTeichman 2006

Non-peptide spiroindane-piperidine small molecule designed at MerckMurphy 1998

Antibody development

Not reported in short-term studies

—

02Dosage Protocols

Parameter

CJC-1295 (no DAC)

MK-677

Standard dose

100 mcg per injectionTeichman 2006

Often paired with ipamorelin in same syringe.

10–25 mg / day oralNass 2008

25 mg used in Nass 2008 elderly trial; 10–15 mg common community dose.

Frequency

1–2× daily (pre-sleep ± morning)

Once daily, oral

Lower / starter dose

50 mcg per dose

5 mg / day

Evidence basis

Phase 1 (CJC-1295 with DAC); analog dataTeichman 2006 Ionescu 2006

No-DAC variant is less studied directly; PK extrapolated from native GHRH.

Phase 2 trials (Nass 2008, Murphy 1998)Nass 2008 Murphy 1998

Duration

8–12 weeks on / 4 off (anecdotal)

8–16 weeks per cycle (off-cycle to reset receptor sensitivity)

Reconstitution

Bacteriostatic water

Oral, no reconstitution

Timing

Pre-sleep + fasted preferred

Pre-sleep preferred for natural GH pulse alignment

Half-life

~30 minIonescu 2006

Short pulse vs CJC-1295-DAC (~8 days). Choose no-DAC for pulsatile, DAC for sustained.

~24 hrNass 2008

Once-daily dosing covers 24 hours.

04Side Effects & Safety

Parameter

CJC-1295 (no DAC)

MK-677

Injection site reaction

Erythema, mild pruritus

—

Flushing / headache

Common transient effect

—

Cortisol elevation

Minimal at standard doses

—

Prolactin elevation

Minimal

—

Glucose intolerance

Possible at high cumulative doses

—

IGF-1 elevation

Dose-dependent; monitor with chronic use

+50–100% sustainedNass 2008

Cancer risk

Contraindicated in active malignancy (GH/IGF-1 axis)

Pregnancy / OB

Avoid

Increased appetite

—

Strong appetite increase via ghrelin agonism

Water retention

—

Mild edema, paresthesias

Glucose tolerance

—

↑ HbA1c +0.3–0.5% in 2-yr elderly trialNass 2008

Cardiovascular

—

No clear adverse signal in trials; congestive heart failure caution

Drowsiness

—

Common, especially during initial weeks

Absolute Contraindications

CJC-1295 (no DAC)

·Active malignancy or cancer history
·Pregnancy / breastfeeding
·Disrupted hypothalamic-pituitary axis

MK-677

·Active malignancy
·Pregnancy / breastfeeding
·Disrupted hypothalamic-pituitary axis
·Congestive heart failure (caution)

Relative Contraindications

CJC-1295 (no DAC)

·Untreated diabetes
·Severe insulin resistance

MK-677

·Untreated diabetes
·Pre-diabetes
·Severe insulin resistance

05Administration Protocol

Parameter

CJC-1295 (no DAC)

MK-677

1. Reconstitution

Add 2 mL bacteriostatic water to 2 mg vial → 1 mg/mL = 100 mcg per 0.1 mL. Roll gently.

Capsule or oral solution. No injection.

2. Injection site

Subcutaneous, abdomen or thigh. Rotate sites.

Oral. Take with or without food.

3. Timing

Pre-sleep preferred. Often combined with ipamorelin in the same syringe.

Pre-sleep preferred — aligns with natural GH pulse.

4. Storage

Lyophilised: room temp, protected from light. Reconstituted: refrigerate 2–8 °C, use within 30 days.

Capsule: room temp ≤25 °C, dry place.

5. Needle

29–31G, 4–8 mm insulin syringe.

Monitor HbA1c every 8–12 weeks during chronic use.

06Stack Synergy

CJC-1295 (no DAC)

+ Ipamorelin

Strong

View Ipamorelin →

CJC-1295 (no DAC) and ipamorelin are the canonical "GHRH + GHRP" dual-axis stack at physiological timing. Both peak within 30 min and clear within 2 hours, producing a sharp, high-amplitude GH pulse closely resembling natural physiology. Preferred over the CJC-1295-DAC + ipamorelin stack when pulsatility (vs sustained elevation) is the goal.

CJC-1295 (no DAC): 100 mcg SQ · pre-sleep
Ipamorelin: 200–300 mcg SQ · same injection
Primary benefit: Pulsatile GH stimulation, recovery, body composition

Teichman 2006 Raun 1998

MK-677

— no documented stacks