Side-by-side · Research reference
MK-677vsSemax
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
APhase 2Reviewed13/45 cited
BHuman-MechanisticDraft12/39 cited
MK-677
Oral GHS · Ibutamoren
Oral capsule · 1×/day
Semax
Cognitive enhancer · Russian Pharma
Intranasal · 2–3×/day during cognitive demand
01Mechanism of Action
Parameter
MK-677
Semax
Primary target
Ghrelin receptor (GHS-R1a)Murphy 1998
BDNF / NGF expression + monoamine modulationKaplan 2017
Pathway
GHS-R1a → Gαq → Ca²⁺ → sustained GH pulses across 24 hrNass 2008
↑ BDNF + NGF synthesis + 5-HT modulation → neuroplasticity + anxiolysis + cognitive enhancementKaplan 2017
Downstream effect
Sustained GH + IGF-1 elevation; appetite stimulation; lean mass preservationNass 2008
Improved memory + attention; reduced anxiety; neuroprotection in ischemiaKaplan 2017
Origin
Non-peptide spiroindane-piperidine small molecule designed at MerckMurphy 1998
Synthetic 7-AA peptide derived from ACTH(4-7) with C-terminal Pro-Gly-Pro stabilising tailKaplan 2017
Antibody development
—
—
02Dosage Protocols
Parameter
MK-677
Semax
Standard dose
10–25 mg / day oralNass 2008
25 mg used in Nass 2008 elderly trial; 10–15 mg common community dose.
200–600 mcg / dose intranasalKaplan 2017
Frequency
Once daily, oral
2–3× per day during cognitive demand
Lower / starter dose
5 mg / day
100 mcg / dose
Evidence basis
Phase 2 trials (Nass 2008, Murphy 1998)Nass 2008Murphy 1998
Human-mechanistic + Russian clinicalKaplan 2017
Duration
8–16 weeks per cycle (off-cycle to reset receptor sensitivity)
10–14 day cycles, repeated PRN
Reconstitution
Oral, no reconstitution
Pre-formulated nasal spray (commercial); research vial: bacteriostatic water
Timing
Pre-sleep preferred for natural GH pulse alignment
Morning + early afternoon
04Side Effects & Safety
Parameter
MK-677
Semax
Increased appetite
Strong appetite increase via ghrelin agonism
—
Water retention
Mild edema, paresthesias
—
Cancer risk
Contraindicated in active malignancy (GH/IGF-1 axis)
—
Cardiovascular
No clear adverse signal in trials; congestive heart failure caution
—
Drowsiness
Common, especially during initial weeks
—
Pregnancy / OB
Avoid
Avoid
Nasal irritation
—
Mild burning or congestion (transient)
Sleep disruption
—
Late-day dosing may interfere with sleep
Headache
—
Uncommon, transient
Long-term safety
—
Limited Western RCT data
Absolute Contraindications
MK-677
- ·Active malignancy
- ·Pregnancy / breastfeeding
- ·Disrupted hypothalamic-pituitary axis
- ·Congestive heart failure (caution)
Semax
- ·Pregnancy / breastfeeding
Relative Contraindications
MK-677
- ·Untreated diabetes
- ·Pre-diabetes
- ·Severe insulin resistance
Semax
- ·Active psychiatric instability
- ·Concurrent strong stimulants
05Administration Protocol
Parameter
MK-677
Semax
1. Form
Capsule or oral solution. No injection.
Pre-formulated nasal spray (commercial) or research vial reconstituted with bacteriostatic water.
2. Site
Oral. Take with or without food.
Intranasal — 2–3 sprays per nostril per dose. Tilt head slightly back.
3. Timing
Pre-sleep preferred — aligns with natural GH pulse.
Morning + early afternoon. Avoid evening (sleep disruption).
4. Storage
Capsule: room temp ≤25 °C, dry place.
Refrigerate after reconstitution; light-protected.
5. Caveat
Monitor HbA1c every 8–12 weeks during chronic use.
Cycle on/off to avoid neurochemical adaptation.
06Stack Synergy
MK-677
— no documented stacks
Semax
+ Selank
ModerateSemax (cognitive enhancer, BDNF/NGF) and Selank (anxiolytic + immune) form the canonical Russian "neuro stack" — both intranasal peptide bioregulators with complementary axes. Semax for cognitive demand; Selank for stress mitigation.
- Semax
- 200–600 mcg intranasal · morning + afternoon
- Selank
- 150–300 mcg intranasal · midday + early evening
- Primary benefit
- Cognitive enhancement + stress mitigation