Side-by-side · Research reference

AHK-CuvsRetatrutide

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

BPhase 2HUMAN-REVIEWED10/41 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

Retatrutide

Triple-receptor agonist · Phase 3

1–12 mgWeekly doseJastreboff 2023

24.2%Body-weight ↓Jastreboff 2023

~6 daysHalf-life (est)

SQ · Abdomen · Once weekly

01Mechanism of Action

Parameter

AHK-Cu

Retatrutide

Primary target

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

GLP-1R + GIPR + Glucagon receptor (triple agonism)Jastreboff 2023

Pathway

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

Triple-receptor activation → ↑insulin (GLP-1+GIP), ↓gastric emptying, ↑lipid handling, ↑energy expenditure (glucagon component)Jastreboff 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

Maximal weight loss across class. Glucagon component drives lipolysis and energy expenditure beyond GLP-1+GIP aloneJastreboff 2023

Feedback intact?

—

Origin

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

Synthetic peptide engineered for balanced affinity at three incretin / glucagon receptorsJastreboff 2023

Antibody development

—

02Dosage Protocols

Parameter

AHK-Cu

Retatrutide

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)

Once weekly

Route

Topical — scalp or dermal application

—

Evidence basis

Ex vivo hair follicle / in vitro DPC studiesPyo 2007

Phase 2 trial; Phase 3 ongoingJastreboff 2023

Duration

Not established — cosmetic protocols typically 8–12 weeks

Indefinite for chronic indication (presumed)

Standard dose

—

12 mg / week (max efficacy)Jastreboff 2023

Phase 2 trial dose. Phase 3 dosing TBD.

Titration schedule

—

2 mg → 4 mg → 8 mg → 12 mg over 16 weeks

Reconstitution

—

Investigational; not commercially available

Timing

—

Any time of day

Half-life

—

~6 days (estimated from class)

04Side Effects & Safety

Parameter

AHK-Cu

Retatrutide

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)

—

GI symptoms

—

Nausea, vomiting, diarrhea (very common, dose-dependent)Jastreboff 2023

Heart rate

—

↑ resting HR (3–7 bpm at 12 mg)Jastreboff 2023

Glucose handling

—

Glycemic improvement; rare hyperglycemia from glucagon component

Pancreatitis risk

—

Class warning

Thyroid C-cell tumours

—

Class warning (presumed)

Pregnancy / OB

—

Avoid (insufficient data)

Absolute Contraindications

AHK-Cu

·Known copper allergy or Wilson's disease

Retatrutide

·MTC personal or family history (presumed class effect)
·Pregnancy / breastfeeding

Relative Contraindications

AHK-Cu

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

Retatrutide

·Severe gastroparesis
·History of pancreatitis
·Severe cardiovascular disease (HR signal)

05Administration Protocol

Parameter

AHK-Cu

Retatrutide

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.

Investigational peptide. Research vials reconstituted with bacteriostatic water per label.

2. Frequency

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

SQ — abdomen, thigh, or upper arm. Rotate weekly.

3. Scalp preparation

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

Once weekly, same day.

4. Storage

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

Refrigerate 2–8 °C. Light-protected.

5. Duration

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

27–31G, 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

Retatrutide

— no documented stacks