Clenbuterol vs MK-677
Well Studied vs Well Studied
monitor Mechanism-based · 51% Both Clenbuterol and MK-677 can raise blood pressure. Monitor BP regularly and consider adding cardiovascular support (cardarine, telmisartan, or similar).
Molecular Data
Clenbuterol MK-677
Weight 277.19 Da 624.77 Da
Half-life ~36 hours ~24 hours
Type Sympathomimetic amine (C12H18Cl2N2O) Non-peptide ghrelin receptor agonist
Key Benefits
Clenbuterol
01 Increased basal metabolic rate and thermogenesis for accelerated fat loss
02 Preferential mobilization of stored body fat through enhanced lipolysis
03 Anti-catabolic effects that help preserve lean muscle mass during caloric restriction
04 Bronchodilation and improved respiratory capacity during intense exercise
05 Appetite suppression in many users, supporting adherence to caloric deficit
06 Oral administration with no injections required
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)
Side Effects
Clenbuterol
Tremors and shaking (especially hands) - most pronounced in the first 3-5 days
Tachycardia (elevated heart rate, typically 10-20 bpm above baseline)
Insomnia and sleep disturbance, particularly with afternoon or evening dosing
Muscle cramps (calves, forearms, back) due to taurine depletion
Increased sweating and elevated body temperature
Headaches, particularly during dose ramp-up
Nervousness, anxiety, and restlessness
Increased blood pressure
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.
Contraindications
Pre-existing cardiovascular disease, cardiomyopathy, or arrhythmia
Uncontrolled hypertension
Hyperthyroidism or thyrotoxicosis
Hypokalemia or electrolyte imbalances
Known hypersensitivity to clenbuterol or sympathomimetic amines
Concurrent use of other stimulants (ephedrine, amphetamines) or MAO inhibitors
Pregnancy or breastfeeding
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Research Evidence
Clenbuterol MK-677
Status Well Studied Well Studied
References 5 studies 7 studies
Latest 2021 July 2024
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.