MK-677 (Ibutamoren) vs PT-141 (Bremelanotide)
Side-by-side comparison of key properties, dosing, and research.
Growth Hormone Peptides
MK-677 (Ibutamoren)Sexual Health & Libido
PT-141 (Bremelanotide)- Summary
- MK-677 (Ibutamoren) is an orally active, non-peptide ghrelin receptor agonist that increases growth hormone and IGF-1 levels. Unlike injectable GHRPs, it can be taken orally and has a 24-hour half-life, making it convenient for sustained GH optimization.
- PT-141 (Bremelanotide) is a cyclic peptide melanocortin receptor agonist that enhances sexual desire and arousal through central nervous system mechanisms. It is FDA-approved as Vyleesi for premenopausal women with hypoactive sexual desire disorder (HSDD).
- Half-Life
- 24 hours
- 2–3 hours
- Admin Route
- Oral
- SubQ
- Research
- —
- —
- Typical Dose
- 10–25 mg
- 0.5–1.75 mg
- Frequency
- Once daily
- As needed (not daily)
- Key Benefits
- Increases lean muscle mass
- Enhances bone density
- Improves sleep quality and REM sleep
- Accelerates recovery from training
- Increases appetite
- May improve skin elasticity and appearance
- Supports fat loss while maintaining muscle
- Oral administration — no injections required
- 24-hour half-life allows once-daily dosing
- Enhances sexual desire and libido in both men and women
- Improves arousal through central nervous system activation
- Effective for psychological erectile dysfunction
- Works for female sexual arousal disorder
- May improve sexual satisfaction and intensity
- Fast-acting — effects within 45–60 minutes
- FDA-approved for HSDD in premenopausal women
- Side Effects
- Increased appetite (significant in some users)
- Water retention and puffiness
- Elevated blood glucose / insulin resistance (monitor in diabetics)
- Lethargy initially
- +2 more
- Nausea (most common — 40% of users in clinical trials)
- Facial flushing and warmth
- Transient blood pressure changes (typically increase then normalize)
- Headache
- +2 more
- Stacks With
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