Side-by-side · Research reference
MK-677vsMOTS-c
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
APhase 2Reviewed13/45 cited
BAnimal-StrongReviewed16/68 cited
MK-677
Oral GHS · Ibutamoren
Oral capsule · 1×/day
MOTS-c
Mitokine · Mitochondria-Encoded
SQ · Variable · 2–3×/week
01Mechanism of Action
Parameter
MK-677
MOTS-c
Primary target
Ghrelin receptor (GHS-R1a)Murphy 1998
Mitochondrial 12S rRNA sORF → folate-AICAR-AMPK axisLee 2015
Pathway
GHS-R1a → Gαq → Ca²⁺ → sustained GH pulses across 24 hrNass 2008
Downstream effect
Sustained GH + IGF-1 elevation; appetite stimulation; lean mass preservationNass 2008
Enhanced fatty acid oxidation, GLUT4-mediated glucose uptake, mitochondrial bioenergetics, anti-inflammationLee 2015
Feedback intact?
Pulsatile pattern preserved despite long half-lifeMurphy 1998
Stress-responsive, AMPK-dependent nuclear translocationKim 2018
Origin
Non-peptide spiroindane-piperidine small molecule designed at MerckMurphy 1998
Endogenous 16-AA mitokine; mtDNA-encoded; declines with age; upregulated by exerciseReynolds 2021
Antibody development
—
—
02Dosage Protocols
Parameter
MK-677
MOTS-c
Standard dose
10–25 mg / day oralNass 2008
25 mg used in Nass 2008 elderly trial; 10–15 mg common community dose.
5–10 mg / weekLee 2015
Experimental, extrapolated from animal data. No human RCT-derived dose.
Frequency
Once daily, oral
2–3× per week
Short half-life may necessitate more frequent dosing for saturation.
Lower / starter dose
5 mg / day
2.5–5 mg / week
Recommended due to limited human data.
Evidence basis
Phase 2 trials (Nass 2008, Murphy 1998)Nass 2008Murphy 1998
Animal + anecdotalLee 2015Reynolds 2021A first-in-human phase 1 study 2021
Phase 1a/1b CB4211 analog trial completed 2021; no native MOTS-c RCT published.
Duration
8–16 weeks per cycle (off-cycle to reset receptor sensitivity)
4–12 weeks (experimental)
Optimal cycle length unknown.
Reconstitution
Oral, no reconstitution
Bacteriostatic water, 1–2 mL
10 mg/mL at 1 mL.
Timing
Pre-sleep preferred for natural GH pulse alignment
Pre-workout or fasted state preferred
Activity-context amplifies AMPK response.
Half-life
~24 hrNass 2008
Once-daily dosing covers 24 hours.
Minutes to hours (estimated)
Systemically unstable; native MOTS-c PK in humans not fully characterised.
03Metabolic / Fat Loss Evidence
Parameter
MK-677
MOTS-c
Primary fat target
—
Diet-induced / metabolic obesity; systemic fat utilization
Quantified reduction
—
Significant HFD fat gain ↓Lee 2015
Murine models, dose-dependent (5 & 15 mg/kg).
IGF-1 impact
—
No direct IGF-1 pathway; AMPK-mediated
Effect on lean mass
—
High dose significantly ↑ lean mass in mice
Triglycerides
—
AMPK-driven FA oxidation suggests TG benefit (not directly measured)
Effect reversibility
—
Unknown — no long-term follow-up data
Key publication
—
Lee Cell Metab 2015 · Reynolds Nat Commun 2021 · Kim Cell Metab 2018Lee 2015Reynolds 2021Kim 2018
04Side Effects & Safety
Parameter
MK-677
MOTS-c
Increased appetite
Strong appetite increase via ghrelin agonism
—
Water retention
Mild edema, paresthesias
—
Cancer risk
Contraindicated in active malignancy (GH/IGF-1 axis)
Contradictory data — some models suggest pro-proliferative effects
Cardiovascular
No clear adverse signal in trials; congestive heart failure caution
Heart palpitations (anecdotal); cardiac hypertrophy reversed in diabetic rats
Drowsiness
Common, especially during initial weeks
—
Pregnancy / OB
Avoid
Avoid — insufficient safety data
Injection site reaction
—
Mild irritation (reported)
Fluid retention / Edema
—
Not reported
CNS / Neurological
—
Insomnia, headache (anecdotal reports)
GI symptoms
—
Nausea, stomach discomfort (reported)
Antibody formation
—
No data (no long-term human trials)
Evidence quality
—
Phase 1 analog (CB4211); preclinical; anecdotal humanA first-in-human phase 1 study 2021
Absolute Contraindications
MK-677
- ·Active malignancy
- ·Pregnancy / breastfeeding
- ·Disrupted hypothalamic-pituitary axis
- ·Congestive heart failure (caution)
MOTS-c
- ·Pregnancy / breastfeeding (insufficient data)
Relative Contraindications
MK-677
- ·Untreated diabetes
- ·Pre-diabetes
- ·Severe insulin resistance
MOTS-c
- ·Active cancer or cancer predisposition
- ·AMPK pathway deficiency (efficacy nullified)
- ·Use with cancer-promoting medications (theoretical)
05Administration Protocol
Parameter
MK-677
MOTS-c
1. Form
Capsule or oral solution. No injection.
Add 1–2 mL bacteriostatic water. At 10 mg/vial, 1 mL gives 10 mg/mL concentration. Roll gently to dissolve.
2. Site
Oral. Take with or without food.
Subcutaneous — abdomen, thigh, or deltoid. Rotate sites to avoid lipohypertrophy. Pinch fat layer.
3. Timing
Pre-sleep preferred — aligns with natural GH pulse.
Pre-workout or fasted state preferred — metabolic context amplifies AMPK response. 2–3× per week.
4. Storage
Capsule: room temp ≤25 °C, dry place.
Lyophilised: room temp, protected from light. Reconstituted: refrigerate, use within 21–30 days. Short systemic stability.
5. Caveat
Monitor HbA1c every 8–12 weeks during chronic use.
27–31G insulin syringe. Short needle (4–6 mm) for SQ delivery. Clean technique mandatory.
06Stack Synergy
MK-677
— no documented stacks
MOTS-c
+ Ipamorelin
ModerateMOTS-c activates AMPK/PGC-1α for mitochondrial efficiency and fatty acid oxidation; ipamorelin stimulates GH for anabolic recovery and sleep depth. Pathways are complementary — MOTS-c handles metabolic flexibility and glucose handling while ipamorelin drives recovery and body recomposition through GH. Theoretical synergy is high; clinical data is lacking.
- MOTS-c
- 5 mg SQ · pre-workout (2–3×/wk)
- Ipamorelin
- 200–300 mcg SQ · pre-sleep (daily)
- Primary benefit
- Metabolic flexibility + GH recovery + ROS reduction