Ingredient or product comparison
GHK-Cu Cosmetic Research Log Track Document: Study Design Comparison
Single-subject pilot (pre/post) Demographics, formulation, application protocol, outcomes 12 weeks Photographic assessment + TEWL Weekly photos, biweekly TEWL Weakest design. Useful only for tolerance screening and protocol refinement before multi-subject tria
This source-based comparison does not add ratings or recommend a winner.
- Single-subject pilot (pre/post)
- Demographics, formulation, application protocol, outcomes
- 12 weeks
- Photographic assessment + TEWL
- Weekly photos, biweekly TEWL
- Weakest design. Useful only for tolerance screening and protocol refinement before multi-subject trials
- Split-face comparative (vehicle vs peptide)
- All 6 sections + randomization log
- 8 weeks minimum
- Blinded visual scoring by independent assessors
- Weekly assessment, monthly instrumental
- Gold standard for topical cosmetic peptides. Eliminates inter-subject variability, requires strict blinding to prevent bias
- Parallel-group RCT (peptide vs placebo)
- All 6 sections + randomization code + blinding verification
- 16 weeks
- Dermal thickness via ultrasound + collagen density biomarkers
- Baseline, week 8, week 16
- Highest evidentiary value but requires >30 subjects per arm for statistical power. Logistically intensive
- Dose-response study (3 concentrations)
- All 6 sections + dose escalation protocol
- Adverse event incidence + efficacy at each dose tier
- Weekly for first 4 weeks, biweekly thereafter
- Essential for defining optimal concentration range. Most peptide studies skip this and use arbitrary doses