Side-by-side · Research reference
PT-141vsSermorelin
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AFDA-ApprovedReviewed13/41 cited
BPhase 3Reviewed14/43 cited
PT-141
MC4R Agonist · FDA-Approved (HSDD)
SQ · Abdomen / thigh · ≥45 min before sex
Sermorelin
GHRH 1-29 fragment · Short-acting
SQ · Pre-sleep · 1×/day
01Mechanism of Action
Parameter
PT-141
Sermorelin
Primary target
Melanocortin-4 receptor (MC4R) in hypothalamusSimerly 2023VYLEESI (bremelanotide injecti 2019
Pituitary GHRH receptorWalker 1994
Pathway
MC4R agonism in paraventricular nucleus → autonomic + neuroendocrine sexual arousal pathwaysSimerly 2023
GHRH-R → Gαs → cAMP → PKA → GH vesicle exocytosisWalker 1994
Downstream effect
Increased sexual desire and arousal; central rather than peripheral mechanismClayton 2015
Pulsatile GH release; subsequent IGF-1 elevationMolteno 2013
Feedback intact?
—
Yes — short pulse preserves feedback
Origin
Cyclic 7-AA peptide derived from α-MSH (agonist Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-OH cyclic)VYLEESI (bremelanotide injecti 2019
Unmodified active 29-AA fragment of human GHRH (1-44)Walker 1994
Antibody development
—
—
02Dosage Protocols
Parameter
PT-141
Sermorelin
Standard dose
1.75 mg SQVYLEESI (bremelanotide injecti 2019
Single dose ≥45 min before anticipated sexual activity. Max 1 dose / 24 hr.
100–500 mcg per injectionMolteno 2013
Frequency
PRN, max 8 doses / month
Once daily, pre-sleep
Lower / starter dose
1 mg (off-label)
100 mcg per dose
Evidence basis
FDA-approved (HSDD pre-menopausal women)VYLEESI (bremelanotide injecti 2019Clayton 2015
Phase 3 (Geref pediatric); clinical practiceWalker 1994Molteno 2013
Duration
PRN; reassess if no benefit after 8 doses
8–12 weeks per cycle
Reconstitution
Pre-filled commercial pen (Vyleesi). Research vial: bacteriostatic water.
Bacteriostatic water
Timing
≥45 min before sexual activity
Pre-sleep, fasted preferred
Half-life
~12 min (plasma)Molteno 2013
Shorter than tesamorelin (~26 min) — simpler GHRH analogue.
04Side Effects & Safety
Parameter
PT-141
Sermorelin
Flushing
Common, transient
—
Injection site reaction
Erythema, mild pain
Mild erythema, transient pain
Headache
Common
—
Hyperpigmentation (focal)
Rare focal skin darkening; reversible after discontinuationVYLEESI (bremelanotide injecti 2019
—
Hypertension (transient)
Mean ↑6 mmHg systolic peaking ~4 h post-dose; resolves within 12 hVYLEESI (bremelanotide injecti 2019
—
Pregnancy / OB
Contraindicated
Avoid
Cardiovascular disease
Use caution; transient BP rise
—
Flushing / headache
—
Common transient effect
IGF-1 elevation
—
Modest at standard doses
Cancer risk
—
Contraindicated in active malignancy (GH/IGF-1 axis)
Glucose handling
—
Generally neutral
Absolute Contraindications
PT-141
- ·Uncontrolled hypertension
- ·Known cardiovascular disease (caution)
- ·Pregnancy
Sermorelin
- ·Active malignancy
- ·Pregnancy / breastfeeding
- ·Disrupted hypothalamic-pituitary axis
Relative Contraindications
PT-141
- ·Pre-existing hyperpigmentation disorders
- ·MC4R-pathway-dependent psychiatric conditions
Sermorelin
- ·Untreated diabetes
05Administration Protocol
Parameter
PT-141
Sermorelin
1. Reconstitution
Vyleesi: pre-filled auto-injector. Research vial: 2 mL bacteriostatic water per 10 mg → 5 mg/mL.
Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL = 250 mcg per 0.1 mL.
2. Injection site
SQ — abdomen or thigh.
SQ — abdomen or thigh. Rotate sites.
3. Timing
≥45 min before sexual activity for peak effect. Effect persists ~6–8 h.
Pre-sleep, fasted.
4. Storage
Vyleesi: room temp ≤30 °C. Research vial: refrigerate after reconstitution.
Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.
5. Needle
Auto-injector (Vyleesi) or 29–31G, 4–8 mm insulin syringe.
29–31G, 4–8 mm insulin syringe.
06Stack Synergy
PT-141
— no documented stacks
Sermorelin
+ Ipamorelin
StrongSermorelin (GHRH analogue) and ipamorelin (selective GHRP) form the prototypical GHRH+GHRP dual-axis stack at the lowest cost. Both peak within 30 min and produce a sharp physiological GH pulse without cortisol/prolactin elevation.
- Sermorelin
- 200–300 mcg SQ · pre-sleep
- Ipamorelin
- 200–300 mcg SQ · same injection
- Primary benefit
- Pulsatile GH stimulation, recovery, body composition