Anastrozole vs MK-677
FDA Approved vs Well Studied
avoid Mechanism-based · 64% Both Anastrozole and MK-677 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
Anastrozole MK-677
Weight 293.37 Da 624.77 Da
Half-life ~40-50 hours ~24 hours
Type Nonsteroidal aromatase inhibitor (triazole derivative) Non-peptide ghrelin receptor agonist
Key Benefits
Anastrozole
01 Potent reduction of circulating estradiol levels (70-80% at standard dose)
02 Prevents gynecomastia during testosterone or anabolic steroid cycles
03 Reduces estrogen-driven water retention and bloating
04 Helps control estrogen-related blood pressure elevation
05 Oral dosing with long half-life allows flexible scheduling (EOD or E3D)
06 Reversible inhibition allows estrogen recovery after discontinuation
07 Well-characterized pharmacokinetics with decades of clinical data
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
Anastrozole
Joint pain, stiffness, or dryness (from reduced estrogen-mediated joint lubrication)
Hot flashes or flushing
Fatigue and general malaise
Mood changes (flat affect, irritability, or low mood)
Decreased libido (when estrogen is suppressed too aggressively)
Headache
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
Known hypersensitivity to anastrozole or any excipients
Premenopausal women (not indicated and potentially harmful to reproductive function)
Pregnancy or breastfeeding (teratogenic risk)
Severe hepatic impairment
Pre-existing severe osteoporosis or high fracture risk
Concurrent use with tamoxifen or estrogen-containing therapies
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Research Evidence
Anastrozole MK-677
Status FDA Approved Well Studied
References 5 studies 7 studies
Latest — July 2024
FDA Approved Yes No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.