SARMs
Evidence: moderate_human
MK-677 (ibutamoren) is an orally active, non-peptide growth hormone secretagogue that mimics ghrelin by binding the ghrelin receptor (GHSR1a) in the hypothalamus and pituitary. This triggers pulsatile growth hormone release via the same physiological mechanism as endogenous ghrelin, preserving the natural episodic GH secretion pattern. MK-677 increases GH, IGF-1, and IGFBP-3 levels to those observed in young adults without affecting cortisol levels. It also stimulates appetite through ghrelin receptor activation in the hypothalamus. Unlike exogenous GH injection, MK-677 maintains the pulsatile GH pattern and stimulates all five GH isoforms.
Standard: Research indicates 10-25 mg daily orally. Clinical trials used 25 mg/day. 10-15 mg may provide GH elevation with fewer side effects.
Maintenance: Research indicates 10-25 mg daily, taken before bed (coincides with nocturnal GH pulse and reduces hunger side effect during waking hours).
Administration: oral
Timing: Take 30-60 minutes before bedtime. This timing leverages the natural nocturnal GH pulse, maximizes sleep quality benefits, and minimizes daytime appetite increase. Half-life ~24 hours ensures once-daily dosing is sufficient.
Duration: Can be used continuously for months to years — no cycling required as it works through physiological GH release mechanisms. Clinical trials ran for up to 2 years. Reassess IGF-1 and metabolic markers every 3-6 months.
MK-677 is technically a growth hormone secretagogue (GHS), not a SARM, but is commercially grouped with SARMs. Its major advantage over exogenous GH is oral dosing, preserved pulsatile GH release, and no HPG axis suppression. The 2-year Nass et al. (2008) trial in healthy elderly showed sustained GH and IGF-1 elevation with increased fat-free mass (+1.1 kg vs. -0.5 kg placebo). The primary concern is metabolic: fasting glucose increased and insulin sensitivity decreased. CRITICAL: Monitor glucose/insulin closely, especially in individuals with pre-diabetes, metabolic syndrome, or family history of diabetes. Required bloodwork: IGF-1 (target upper-normal for age), fasting glucose, fasting insulin, HbA1c (every 3 months), CMP, lipid panel. No liver monitoring specifically required (not hepatotoxic), but standard metabolic panels are essential. Medical supervision required.
Not FDA-approved. Research chemical — source from vendors with third-party HPLC COA. Oral liquid or capsule form. Stable at room temperature. Note: MK-677 is technically not a SARM (does not bind the androgen receptor) but is commonly categorized alongside SARMs in the market.
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