# GHK-Cu Dosage in Research: Topical, Injectable, and Intranasal Protocols > GHK-Cu dosage parameters from the research literature — topical concentrations, rodent injectable doses, intranasal protocols, and the formulation considerations that affect delivery. ## Research-Context Dosing: What the Literature Reports GHK-Cu is a research peptide — it has no FDA-approved therapeutic indication for injectable or systemic use. The dosing information below describes what was administered in published research protocols, organized by study type and model. This is not a dosing guide; it is a summary of what has been studied. Understanding [GHK-Cu dosage parameters](/dosage) requires distinguishing topical use (where controlled human trial data exist) from injectable use (where the literature is entirely preclinical). ## GHK-Cu Dosage Parameters in Research Literature **Topical (cosmetic and clinical formulations)** Concentrations between 0.1% and 5% GHK-Cu have been used in cosmetic serum and cream formulations studied in placebo-controlled trials. The 12-week photoaging trial [4] and the 8-week nano-lipid carrier study [6] used topical formulations without specifying concentration in the published abstracts; the 6-month hair growth RCT used a complex formulation at 100 mg/mL and 50 mg/mL [12]. A 2025 review characterized topical delivery challenges directly: GHK-Cu's clogP of -2.24 restricts passive stratum corneum penetration. Palmitoylated GHK-Cu (Pal-GHK) achieves 4.61% penetration vs. native GHK-Cu at much lower rates [24]. Liposomal encapsulation, ionic liquid microemulsions, and microneedle pretreatment are under active investigation as enhancement strategies [8, 13, 24]. An ex vivo human skin diffusion study established a permeability coefficient of 2.43±0.51×10⁻⁴ cm/h for GHK-Cu through dermatomed skin, with 97±6.6 μg/cm² retained as a dermal depot over 48 hours [20]. This indicates that topically applied GHK-Cu does penetrate to the dermis and form a local reservoir — supporting the mechanism by which topical formulations reach dermal fibroblasts. **Injectable (rodent preclinical)** Published rodent injectable doses vary by model: - Emphysema (COPD mouse model): 0.2, 2, and 20 μg/g/day intraperitoneal on alternate days [10] - Pulmonary fibrosis (bleomycin model): 2.6, 26, and 260 μg/mL/day intraperitoneal from day 4–21 [11] - Silicosis model: 2 and 20 mg/kg intraperitoneal [18] **Intranasal (rodent cognitive models)** - Aging mice (20 months old): 15 mg/kg/day intranasal for 8 weeks [14] - 5xFAD Alzheimer's model: 15 mg/kg three times weekly for 3 months [15] **In vitro effective range** Collagen and glycosaminoglycan synthesis stimulation in human fibroblast cultures: 10⁻¹² to 10⁻⁹ M (with maximum activity at 10⁻⁹ M) [1]. Keratinocyte proliferation studies used 1–10 nM concentrations [5]. ## GHK-Cu Pharmacokinetics and Half-Life No rigorous human pharmacokinetic study has been published for GHK-Cu. Half-life, peak plasma concentration (Cmax), area under the curve, bioavailability, or tissue distribution after subcutaneous or intranasal administration in humans are not available in the published literature. What is known: - GHK-Cu is a small tripeptide (340.4 Da). Small peptides are subject to peptidase degradation in plasma. - Subcutaneous or intranasal administration would bypass first-pass hepatic metabolism. - Topical application creates a dermal depot: 97 μg/cm² retained over 48 hours in an ex vivo diffusion study [20], suggesting prolonged local availability at the application site. - Plasma GHK levels in healthy adults are endogenous and measurable (approximately 200 ng/mL at age 20, 80 ng/mL by age 60 [3]); exogenous GHK-Cu administration would add to this baseline. Pickart estimated a human therapeutic systemic dose in the range of 100–200 mg based on rodent effective-dose extrapolation, but this estimate has not been validated in published human trials. For researchers investigating GHK-Cu, the pharmacokinetic gap is one of the most significant open questions in the literature. ## Administration Routes in GHK-Cu Research Published research has used the following administration routes: 1. **Topical (serums, creams, nano-lipid carriers, liposomes, ionic liquid microemulsions, wound dressings)** — the most studied route; multiple human controlled trials confirm skin delivery and efficacy endpoints [4, 6, 8, 13, 20, 24] 2. **Intraperitoneal injection** — standard rodent route; used in COPD, fibrosis, silicosis, and acute lung injury models [10, 11, 18] 3. **Intranasal** — used specifically in aging and Alzheimer's mouse models to target central nervous system effects without peripheral injection [14, 15] 4. **Wound dressing matrix** — collagen dressings loaded with GHK-Cu applied directly to wound surfaces in diabetic and ischemic rodent models [7] Intraperitoneal injection is a rodent-specific administration route that does not correspond to common human parenteral routes (subcutaneous, intramuscular, intravenous). Translating rodent IP doses to human dosing requires species-scale adjustment and pharmacokinetic studies that have not been published for GHK-Cu. For injectable preparations used in some functional medicine or research contexts: these are not FDA-approved therapeutic formulations, and no published clinical trial data characterize their efficacy, dosing, or safety in humans. ## Formulation and Stability Considerations GHK-Cu stability is pH-sensitive. The copper-peptide complex is more stable at physiological pH (7.4) than at acidic pH. Common cosmetic acidic actives — AHAs (glycolic acid, lactic acid), BHAs (salicylic acid), and high-concentration vitamin C serums — can destabilize GHK-Cu or compete for copper binding [24]. Separate application timing (e.g., morning vs. evening) is the standard recommendation in topical formulation protocols when GHK-Cu is used alongside acidic actives. Advanced delivery systems under investigation: - **Liposomal encapsulation:** improves stability and skin penetration; studied in wound healing models [8] - **Nano-lipid carriers (NLC):** 8-week human trial achieved 31.6% wrinkle reduction [6] - **Ionic liquid microemulsions:** 2% GHK-Cu CaT-ME formulation drove follicles into anagen in 6 days in mice (vs. 9 days for topical minoxidil) [13] - **Palmitoylation (Pal-GHK-Cu):** increases lipophilicity; 4.61% stratum corneum penetration vs. much lower rates for native GHK-Cu [24] - **Cell-penetrating peptide (CPP) conjugates:** early-stage delivery enhancement strategy identified in 2025 review [24] - **Microneedle pretreatment:** bypasses stratum corneum barrier; identified in 2025 review as an evidence-based enhancement approach [24] The formulation question is currently one of the most active areas of GHK-Cu applied research. --- Wound healing, collagen, and tissue remodeling: plain-language summaries of the GHK-Cu research record, cited study by study, written by no clinic and sold by no one.