Side-by-side · Research reference

AHK-CuvsPT-141

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-MechanisticHUMAN-REVIEWED14/43 cited

BFDA-ApprovedHUMAN-REVIEWED13/41 cited

AHK-Cu

Tripeptide-Copper Complex · Cosmetic

10⁻¹² – 10⁻⁹ MActive range (in vitro)Pyo 2007

Dermal papilla cellsPrimary targetPyo 2007

TopicalRoute

Topical · Scalp / Skin

PT-141

MC4R Agonist · FDA-Approved (HSDD)

1.75 mgPer doseVYLEESI (bremelanotide injecti 2019

Pre-sexTimingVYLEESI (bremelanotide injecti 2019

~2.7 hrHalf-lifeVYLEESI (bremelanotide injecti 2019

SQ · Abdomen / thigh · ≥45 min before sex

01Mechanism of Action

Parameter

AHK-Cu

PT-141

Primary target

Dermal papilla cells (DPCs) — specialized fibroblasts in hair follicle morphogenesisPyo 2007

Melanocortin-4 receptor (MC4R) in hypothalamusSimerly 2023 VYLEESI (bremelanotide injecti 2019

Pathway

AHK-Cu → DPC proliferation → VEGF elevation, TGF-β1 suppression → Angiogenesis, follicle elongationPyo 2007

MC4R agonism in paraventricular nucleus → autonomic + neuroendocrine sexual arousal pathwaysSimerly 2023

Downstream effect

Stimulates hair follicle elongation ex vivo, reduces dermal papilla cell apoptosis, elevates Bcl-2/Bax ratio, reduces cleaved caspase-3 and PARPPyo 2007

Increased sexual desire and arousal; central rather than peripheral mechanismClayton 2015

Feedback intact?

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Origin

Synthetic tripeptide with Cu²⁺ chelation — alanine substitution variant of GHK-Cu

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

AHK-Cu

PT-141

Effective concentration (in vitro)

10⁻¹² – 10⁻⁹ MPyo 2007

Stimulated human hair follicle elongation ex vivo and DPC proliferation in vitro.

—

Topical formulation

0.001–0.01% (estimated cosmetic range)

No standardized human protocol published — extrapolated from in vitro data.

—

Frequency

Once or twice daily (topical application)

PRN, max 8 doses / month

Route

Topical — scalp or dermal application

—

Evidence basis

Ex vivo hair follicle / in vitro DPC studiesPyo 2007

FDA-approved (HSDD pre-menopausal women)VYLEESI (bremelanotide injecti 2019 Clayton 2015

Duration

Not established — cosmetic protocols typically 8–12 weeks

PRN; reassess if no benefit after 8 doses

Standard dose

—

1.75 mg SQVYLEESI (bremelanotide injecti 2019

Single dose ≥45 min before anticipated sexual activity. Max 1 dose / 24 hr.

Lower / starter dose

—

1 mg (off-label)

Reconstitution

—

Pre-filled commercial pen (Vyleesi). Research vial: bacteriostatic water.

Timing

—

≥45 min before sexual activity

Half-life

—

~2.7 hrVYLEESI (bremelanotide injecti 2019

04Side Effects & Safety

Parameter

AHK-Cu

PT-141

Local irritation

Mild erythema, pruritus at application site (copper peptide class effect)

—

Copper sensitivity

Rare hypersensitivity reaction in copper-sensitive individuals

—

Systemic absorption

Minimal via topical route — systemic copper toxicity unlikely at cosmetic doses

—

Data limitations

No published human safety trials — cosmetic use presumed safe per class precedent (GHK-Cu)

—

Nausea

—

Common (~40%); often transientVYLEESI (bremelanotide injecti 2019

Flushing

—

Common, transient

Injection site reaction

—

Erythema, mild 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

Cardiovascular disease

—

Use caution; transient BP rise

Absolute Contraindications

AHK-Cu

·Known copper allergy or Wilson's disease

PT-141

·Uncontrolled hypertension
·Known cardiovascular disease (caution)
·Pregnancy

Relative Contraindications

AHK-Cu

·Broken or inflamed skin (increased absorption risk)
·Concurrent use of other copper-containing formulations

PT-141

·Pre-existing hyperpigmentation disorders
·MC4R-pathway-dependent psychiatric conditions

05Administration Protocol

Parameter

AHK-Cu

PT-141

1. Topical application

Apply to clean, dry scalp or target dermal area. Typical cosmetic formulations: 0.001–0.01% AHK-Cu in serum or cream base.

Vyleesi: pre-filled auto-injector. Research vial: 2 mL bacteriostatic water per 10 mg → 5 mg/mL.

2. Frequency

Once or twice daily. Evening application preferred for overnight contact time.

SQ — abdomen or thigh.

3. Scalp preparation

For hair growth: apply directly to scalp, massage gently. No need to rinse. Allow absorption for minimum 2–4 hours.

≥45 min before sexual activity for peak effect. Effect persists ~6–8 h.

4. Storage

Room temperature, protected from light. Copper complexes may degrade in UV exposure.

Vyleesi: room temp ≤30 °C. Research vial: refrigerate after reconstitution.

5. Duration

Minimum 8–12 weeks to assess efficacy in hair growth applications, per typical cosmetic peptide protocols.

Auto-injector (Vyleesi) or 29–31G, 4–8 mm insulin syringe.

06Stack Synergy

AHK-Cu

+ GHK-Cu

Moderate

View GHK-Cu →

Both tripeptide-copper complexes share overlapping angiogenic and wound-healing mechanisms (VEGF elevation, TGF-β modulation, fibroblast proliferation). AHK-Cu's alanine substitution may offer distinct receptor affinity or pharmacokinetics. Co-formulation could provide complementary dermal signaling, though no direct synergy studies exist. Often used interchangeably or in alternating protocols.

AHK-Cu: 0.001–0.01% topical · AM
GHK-Cu: 0.001–0.01% topical · PM
Frequency: Daily alternation or combined formulation
Primary benefit: Comprehensive dermal regeneration, angiogenesis, hair follicle support

PT-141

— no documented stacks