Side-by-side · Research reference

IpamorelinvsMK-677

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

APhase 1Reviewed21/57 cited

BPhase 2Reviewed13/45 cited

Ipamorelin

Selective GHRP · Ghrelin Mimetic

200–300 mcgPer doseRaun 1998

Phase 1Evidence levelRaun 1998 Sigalos 2018

~2 hrHalf-lifeRaun 1998

SQ · Multiple sites · 1–3×/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

Ipamorelin

MK-677

Primary target

Ghrelin receptor (GHS-R1a) on anterior pituitaryRaun 1998

Ghrelin receptor (GHS-R1a)Murphy 1998

Pathway

GHS-R1a binding → Gαq/11 → ↑intracellular Ca²⁺ → GH vesicle exocytosisRaun 1998 Bowers 1991

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

Downstream effect

GH pulse amplification, IGF-1 elevation, recovery and lipolytic effectsBowers 2002

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

Feedback intact?

Yes — pulsatile pattern preserved; somatostatin feedback activeBowers 2002

Pulsatile pattern preserved despite long half-lifeMurphy 1998

Origin

Pentapeptide H-Aib-His-D-2-Nal-D-Phe-Lys-NH₂; rationally designed for ghrelin-receptor selectivityRaun 1998

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

Antibody development

Not reported in short-term studies

—

02Dosage Protocols

Parameter

Ipamorelin

MK-677

Standard dose

200–300 mcg per injectionRaun 1998

Anecdotal community range; clinical doses 1–3 mg IV in trials.

10–25 mg / day oralNass 2008

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

Frequency

1–3× per day

Once daily pre-sleep is most common; twice or thrice for advanced users.

Once daily, oral

Lower / starter dose

100 mcg per dose

5 mg / day

Evidence basis

Phase 1 + clinical practiceRaun 1998 Sigalos 2018

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

Duration

8–12 weeks on / 4 weeks off (anecdotal)

GHS-R desensitisation reported with continuous dosing.

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

Reconstitution

Bacteriostatic water; typical 2 mL per 5 mg vial

Oral, no reconstitution

Timing

Pre-sleep + fasted preferred; 30 min away from food

Pre-sleep preferred for natural GH pulse alignment

Half-life

~2 hoursRaun 1998

Longer than GHRP-6 (15 min); shorter than CJC-1295-DAC (~8 days).

~24 hrNass 2008

Once-daily dosing covers 24 hours.

04Side Effects & Safety

Parameter

Ipamorelin

MK-677

Cortisol elevation

Negligible vs other GHRPsRaun 1998

—

Prolactin elevation

NegligibleRaun 1998

—

Hunger

Mild appetite increase via ghrelin-receptor crosstalk

—

Injection site reaction

Mild irritation possible

—

GH excess (overdose)

Joint pain, edema, insulin resistance

—

IGF-1 elevation

Dose-dependent; monitor with chronic high-dose use

+50–100% sustainedNass 2008

Cancer risk

Theoretical via GH/IGF-1 axis; contraindicated in active malignancy

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

Ipamorelin

·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

Ipamorelin

·Untreated diabetes
·Severe insulin resistance
·Concurrent corticosteroid use (theoretical desensitisation)

MK-677

·Untreated diabetes
·Pre-diabetes
·Severe insulin resistance

05Administration Protocol

Parameter

Ipamorelin

MK-677

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL. Roll gently. Solution should be clear.

Capsule or oral solution. No injection.

2. Injection site

Subcutaneous, abdomen or thigh. Rotate sites. Pinch fat for shallow SQ delivery.

Oral. Take with or without food.

3. Timing

Pre-sleep optimal — aligns with natural GH pulse. Some protocols add a morning fasted dose.

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

Ipamorelin

+ Tesamorelin

Strong

View Tesamorelin →

Ipamorelin (GHRP) + tesamorelin (GHRH analogue) is the textbook dual-axis GH stack. They activate two distinct pituitary receptors — the ghrelin receptor and the GHRH receptor — producing a synergistic GH pulse larger than either alone. Ipamorelin's selectivity (no cortisol/prolactin spike) makes it the ideal GHRP partner for long-term protocols.

Ipamorelin: 200–300 mcg SQ · pre-sleep
Tesamorelin: 2 mg SQ · same injection · pre-sleep
Primary benefit: Maximal GH pulsatility, fat loss, recovery, sleep depth

Raun 1998 Bowers 2002

+ CJC-1295 (no DAC)

Strong

View CJC-1295 (no DAC) →

CJC-1295 (no DAC) is a short-acting GHRH analogue. Combined with ipamorelin (GHRP), the pulse is amplified across both receptor systems with timing similar to native physiology. Without the DAC modification, the stack maintains sharp peaks rather than the sustained elevation seen with CJC-1295-DAC + ipamorelin.

Ipamorelin: 200–300 mcg SQ · pre-sleep
CJC-1295 (no DAC): 100 mcg SQ · same injection
Primary benefit: Pulsatile GH stimulation matching physiological pattern

Teichman 2006 Ionescu 2006

MK-677

— no documented stacks