Side-by-side · Research reference
GHRP-2vsPT-141
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
APhase 2Reviewed15/42 cited
BFDA-ApprovedReviewed13/41 cited
GHRP-2
Hexapeptide GHRP · Phase 2 (clinical diagnostic)
SQ · Multiple sites · 1–3×/day
PT-141
MC4R Agonist · FDA-Approved (HSDD)
SQ · Abdomen / thigh · ≥45 min before sex
01Mechanism of Action
Parameter
GHRP-2
PT-141
Primary target
Ghrelin receptor (GHS-R1a) on anterior pituitaryBowers 1990
Melanocortin-4 receptor (MC4R) in hypothalamusSimerly 2023VYLEESI (bremelanotide injecti 2019
Pathway
GHS-R1a → Gαq → Ca²⁺ → GH vesicle exocytosisBowers 2002
MC4R agonism in paraventricular nucleus → autonomic + neuroendocrine sexual arousal pathwaysSimerly 2023
Downstream effect
Strong GH pulse + IGF-1 elevation; appetite increase via ghrelin agonismBowers 2002
Increased sexual desire and arousal; central rather than peripheral mechanismClayton 2015
Feedback intact?
Yes, with somatostatin feedback active
—
Origin
Synthetic hexapeptide; developed by Bowers/Tulane group in the 1980sBowers 1990
Cyclic 7-AA peptide derived from α-MSH (agonist Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-OH cyclic)VYLEESI (bremelanotide injecti 2019
Antibody development
—
—
02Dosage Protocols
Parameter
GHRP-2
PT-141
Standard dose
100–300 mcg per injectionBowers 1990
1.75 mg SQVYLEESI (bremelanotide injecti 2019
Single dose ≥45 min before anticipated sexual activity. Max 1 dose / 24 hr.
Frequency
1–3× per day
PRN, max 8 doses / month
Lower / starter dose
50 mcg per dose
1 mg (off-label)
Evidence basis
Phase 2 + clinical diagnostic useBowers 1990
FDA-approved (HSDD pre-menopausal women)VYLEESI (bremelanotide injecti 2019Clayton 2015
Duration
8–12 weeks on / 4 off (anecdotal)
PRN; reassess if no benefit after 8 doses
Reconstitution
Bacteriostatic water
Pre-filled commercial pen (Vyleesi). Research vial: bacteriostatic water.
Timing
Pre-sleep + fasted preferred
≥45 min before sexual activity
04Side Effects & Safety
Parameter
GHRP-2
PT-141
Prolactin elevation
Mild but measurable
—
Hunger
Strong appetite increase
—
Injection site reaction
Mild erythema
Erythema, mild pain
IGF-1 elevation
Strong; monitor with chronic high-dose use
—
Cancer risk
Contraindicated in active malignancy
—
Pregnancy / OB
Avoid
Contraindicated
Flushing
—
Common, transient
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
Cardiovascular disease
—
Use caution; transient BP rise
Absolute Contraindications
GHRP-2
- ·Active malignancy
- ·Pregnancy / breastfeeding
PT-141
- ·Uncontrolled hypertension
- ·Known cardiovascular disease (caution)
- ·Pregnancy
Relative Contraindications
GHRP-2
- ·Untreated diabetes
PT-141
- ·Pre-existing hyperpigmentation disorders
- ·MC4R-pathway-dependent psychiatric conditions
05Administration Protocol
Parameter
GHRP-2
PT-141
1. Reconstitution
Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.
Vyleesi: pre-filled auto-injector. Research vial: 2 mL bacteriostatic water per 10 mg → 5 mg/mL.
2. Injection site
SQ — abdomen or thigh. Rotate sites.
SQ — abdomen or thigh.
3. Timing
Pre-sleep + fasted preferred.
≥45 min before sexual activity for peak effect. Effect persists ~6–8 h.
4. Storage
Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.
Vyleesi: room temp ≤30 °C. Research vial: refrigerate after reconstitution.
5. Needle
29–31G, 4–8 mm insulin syringe.
Auto-injector (Vyleesi) or 29–31G, 4–8 mm insulin syringe.
06Stack Synergy
GHRP-2
+ CJC-1295 (no DAC)
StrongGHRP-2 + CJC-1295-no-DAC is a higher-amplitude alternative to the ipamorelin + CJC-1295 stack. GHRP-2 produces a stronger pulse but with cortisol + prolactin signal — choose when maximum GH amplitude is the goal and the side-effect tolerance is acceptable.
- GHRP-2
- 100–200 mcg SQ · pre-sleep
- CJC-1295 (no DAC)
- 100 mcg SQ · same injection
- Primary benefit
- High-amplitude GH pulse, body composition
PT-141
— no documented stacks