MK-677 vs Tamoxifen
Well Studied vs FDA Approved
avoid Mechanism-based · 64% Both MK-677 and Tamoxifen 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 Tamoxifen
Weight 624.77 Da 371.51 Da
Half-life ~24 hours ~5-7 days
Type Non-peptide ghrelin receptor agonist Triphenylethylene-derived selective estrogen receptor modulator
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)
Tamoxifen
01 Blocks estrogen receptor signaling in breast tissue, preventing and treating gynecomastia
02 Stimulates LH and FSH production by antagonizing hypothalamic estrogen receptors
03 Restores endogenous testosterone production during post-cycle therapy
04 Partial estrogen agonist activity in bone preserves bone mineral density
05 Extremely long half-life allows for flexible dosing schedules
06 Decades of clinical use with a well-characterized safety and efficacy profile
07 Oral administration with no injections or reconstitution required
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.
Tamoxifen
Hot flashes and night sweats
Nausea or gastrointestinal discomfort
Mood swings, irritability, or emotional lability
Fatigue during initial weeks of use
Headache
Contraindications
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
History of deep vein thrombosis, pulmonary embolism, or other thromboembolic events
Known hypersensitivity to tamoxifen citrate or any excipients
Concurrent warfarin or coumarin-type anticoagulant therapy (increased bleeding risk)
Pregnancy or planned pregnancy (category D -- known teratogenic risk)
Pre-existing endometrial hyperplasia or uterine cancer
Severe hepatic impairment
Research Evidence
MK-677 Tamoxifen
Status Well Studied FDA Approved
References 7 studies 5 studies
Latest July 2024 —
FDA Approved No Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.