MK-677 vs Phenylpiracetam
Well Studied vs Moderate Research
monitor Mechanism-based · 51% Both MK-677 and Phenylpiracetam can raise blood pressure. Monitor BP regularly and consider adding cardiovascular support (cardarine, telmisartan, or similar).
Molecular Data
MK-677 Phenylpiracetam
Weight 624.77 Da 218.25 Da
Half-life ~24 hours ~3-5 hours
Type Non-peptide ghrelin receptor agonist Racetam derivative (C12H14N2O2)
Key Benefits
MK-677
01 97% increase in 24-hour growth hormone secretion
02 40-72% elevation in IGF-1 levels
03 Enhanced sleep quality with improved REM patterns
04 Preferential lean tissue gains of 1.1-2.7kg over 8-12 months
05 15% basal metabolic rate increase within 2 weeks
06 Oral administration (no injections required)
Phenylpiracetam
01 Potent cognitive enhancement including improved memory, focus, and information processing speed
02 Psychostimulant properties that increase motivation, mental energy, and alertness without the jitteriness of classical stimulants
03 Physical performance enhancement through improved stamina, reduced perception of effort, and increased exercise tolerance
04 Enhanced cold tolerance -- a unique property among nootropics, originally developed for extreme-environment performance
05 Anxiolytic effects at standard doses, reducing stress reactivity without sedation
06 Anticonvulsant activity demonstrated in preclinical models
Side Effects
MK-677
Appetite stimulation (>50% of users)
Water retention (30-40%)
Lethargy (20-30%)
Fasting glucose elevation (5-15mg/dL)
Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.
Phenylpiracetam
Insomnia, particularly if taken in the afternoon or evening -- the stimulant effects can persist for several hours after dosing
Irritability and overstimulation, especially at higher doses or when combined with other stimulants
Headache, most commonly caused by increased acetylcholine demand without adequate choline supplementation
Rapid tolerance development -- the most significant practical limitation, requiring intermittent dosing schedules to maintain efficacy
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Known hypersensitivity to phenylpiracetam or other racetams
Severe hypertension or cardiovascular disease (due to stimulant properties)
Pregnancy and breastfeeding (insufficient safety data)
Severe hepatic or renal impairment
Competitive athletes subject to WADA testing (phenylpiracetam is a prohibited substance under Section S6: Stimulants)
Research Evidence
MK-677 Phenylpiracetam
Status Well Studied Moderate Research
References 7 studies 5 studies
Latest July 2024 —
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.