MK-677 vs Primobolan
Well Studied vs Well Studied
avoid Mechanism-based · 64% Both MK-677 and Primobolan carry hepatotoxic risk. Combining hepatotoxic compounds significantly increases liver damage potential. If unavoidable, include liver support (TUDCA/NAC) and monitor ALT/AST frequently.
Molecular Data
MK-677 Primobolan
Weight 624.77 Da 302.45 Da (base)
Half-life ~24 hours ~10 days (enanthate)
Type Non-peptide ghrelin receptor agonist DHT-derivative steroid (C20H30O2)
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)
Primobolan
01 Lean muscle mass preservation during caloric deficits with minimal water retention
02 Does not aromatize to estrogen, eliminating estrogen-related side effects
03 One of the mildest androgenic profiles among anabolic steroids, with reduced risk of acne, aggression, and prostate issues
04 Injectable form is non-hepatotoxic, allowing extended cycle durations
05 Strong anti-catabolic properties through glucocorticoid receptor modulation
06 Immune-enhancing effects at moderate therapeutic doses
07 Quality, keepable muscle gains without the bloated appearance common with aromatizing steroids
08 Compatible with long cycle lengths (16-20 weeks) due to mild overall impact on health markers
Dosing Protocols
MK-677
Start 12.5mg daily, increase to 25mg based on tolerance / Once daily, preferably at bedtime on empty stomach
Primobolan
400-800 mg/week (injectable) or 50-100 mg/day (oral) / 1-2x per week (enanthate) or daily (oral acetate)
Lean Mass Preservation - Cutting 400-600 mg/week 2x per week (split dose)
Lean Bulking 600-800 mg/week 2x per week (split dose)
Female Protocol 50-100 mg/week 1x per week
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.
Primobolan
Suppression of natural testosterone production (dose-dependent, less suppressive than many other anabolic steroids but still significant)
Hair thinning or accelerated male pattern baldness (DHT derivative -- this is the most commonly reported side effect in susceptible individuals)
Adverse lipid changes, particularly HDL suppression (moderate compared to other anabolic steroids)
Mild acne or oily skin (less pronounced than testosterone or other androgens)
Injection site discomfort from larger oil volumes required at performance doses
Gradual decline in natural testosterone production requiring post-cycle therapy
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Prostate cancer (active or history of hormone-sensitive prostate cancer)
Breast cancer in males or females
Pregnancy or potential for pregnancy (teratogenic risk -- fetal virilization)
Severe hepatic impairment (particularly relevant for oral acetate form)
Known hypersensitivity to metenolone or formulation components
Hypercalcemia
Polycythemia (hematocrit above 54% at baseline)
Uncontrolled cardiovascular disease or severe dyslipidemia
Research Evidence
MK-677 Primobolan
Status Well Studied Well Studied
References 7 studies 4 studies
Latest July 2024 January 2017
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.