Side-by-side · Research reference
PT-141vsSS-31
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 3Reviewed9/43 cited
PT-141
MC4R Agonist · FDA-Approved (HSDD)
SQ · Abdomen / thigh · ≥45 min before sex
SS-31
Cardiolipin-binding · Mitochondrial protective
SQ · Abdomen · Once daily
01Mechanism of Action
Parameter
PT-141
SS-31
Primary target
Melanocortin-4 receptor (MC4R) in hypothalamusSimerly 2023VYLEESI (bremelanotide injecti 2019
Cardiolipin in inner mitochondrial membraneSzeto 2014
Pathway
MC4R agonism in paraventricular nucleus → autonomic + neuroendocrine sexual arousal pathwaysSimerly 2023
Cardiolipin binding → cristae stabilisation → ETC integrity → reduced ROS + preserved ATP synthesisSzeto 2014Szilagyi 2009
Downstream effect
Increased sexual desire and arousal; central rather than peripheral mechanismClayton 2015
Mitochondrial bioenergetic preservation; cardio-, neuro-, and reno-protective effects in animal + clinical studiesSzeto 2014
Feedback intact?
—
—
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
Synthetic tetrapeptide D-Arg-Dmt-Lys-Phe-NH₂; cell-permeable, mitochondrial-selectiveSzeto 2014
Antibody development
—
—
02Dosage Protocols
Parameter
PT-141
SS-31
Standard dose
1.75 mg SQVYLEESI (bremelanotide injecti 2019
Single dose ≥45 min before anticipated sexual activity. Max 1 dose / 24 hr.
40 mg / day SQ (clinical trials)Szeto 2014
Anecdotal community range 5-10 mg/day. Phase 3 trials use 40 mg.
Frequency
PRN, max 8 doses / month
Once daily
Lower / starter dose
1 mg (off-label)
5 mg / day (anecdotal)
Evidence basis
FDA-approved (HSDD pre-menopausal women)VYLEESI (bremelanotide injecti 2019Clayton 2015
Multiple Phase 3 trials (Barth, AMD, ischemia-reperfusion)Szeto 2014Szilagyi 2009
Duration
PRN; reassess if no benefit after 8 doses
Indefinite for mitochondrial disease; cycled for healthspan use
Reconstitution
Pre-filled commercial pen (Vyleesi). Research vial: bacteriostatic water.
Bacteriostatic water
Timing
≥45 min before sexual activity
Morning fasted preferred; pre-workout for exercise-induced mitochondrial stress
04Side Effects & Safety
Parameter
PT-141
SS-31
Flushing
Common, transient
—
Injection site reaction
Erythema, mild pain
Erythema, mild pruritus
Headache
Common
Reported in some Phase 3 trials
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 — insufficient data
Cardiovascular disease
Use caution; transient BP rise
—
GI symptoms
—
Nausea (uncommon)
Cardiovascular
—
Cardio-protective in studies; no signal of harm
Absolute Contraindications
PT-141
- ·Uncontrolled hypertension
- ·Known cardiovascular disease (caution)
- ·Pregnancy
SS-31
- ·Pregnancy / breastfeeding
- ·Hypersensitivity to peptide
Relative Contraindications
PT-141
- ·Pre-existing hyperpigmentation disorders
- ·MC4R-pathway-dependent psychiatric conditions
SS-31
- ·None established
05Administration Protocol
Parameter
PT-141
SS-31
1. Reconstitution
Vyleesi: pre-filled auto-injector. Research vial: 2 mL bacteriostatic water per 10 mg → 5 mg/mL.
Add bacteriostatic water per label. Light-protected handling.
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.
Morning fasted; pre-workout for exercise-augmented mitochondrial stress.
4. Storage
Vyleesi: room temp ≤30 °C. Research vial: refrigerate after reconstitution.
Lyophilised: refrigerate, 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
SS-31
+ MOTS-c
ModerateSS-31 and MOTS-c address mitochondrial decline through complementary axes. SS-31 protects existing mitochondrial structure (cardiolipin binding, cristae stabilisation). MOTS-c upregulates AMPK/PGC-1α, triggering biogenesis of new mitochondria. Together they pair preservation with renewal — anecdotally favoured in healthspan and post-cardio-event recovery protocols.
- SS-31
- 5–10 mg SQ · daily morning
- MOTS-c
- 5 mg SQ · 2× per week pre-workout
- Primary benefit
- Mitochondrial preservation + biogenesis