Cosmetic peptide research questions — skin, hair, and pigmentation research the community is running

Kicking off this discussion thread for ongoing community input on cosmetic peptide research questions. This category covers a wider range of compounds and applications than most other categories — copper peptides for skin, melanocortin agonists for pigmentation, hair-loss-targeted peptides, and the topical versus injected route question that affects every protocol design choice. Plenty of room for productive Q&A. Reply with your own questions or respond to anyone else's.

Specific questions or experiences worth sharing.

GHK-Cu protocol experiences (topical). If a research protocol used topical GHK-Cu for skin endpoints, what concentration was the formulation, what application frequency was used, and over what timeframe? What endpoints were tracked — skin elasticity, fine lines, pigmentation, redness, wound healing? Did the protocol use a vendor formulation or a custom-mixed serum from raw GHK-Cu? Specific concentration and protocol detail is more useful than general "GHK-Cu helped my skin" framing.

GHK-Cu protocol experiences (injected). If a protocol used injected GHK-Cu rather than topical, what was the rationale for choosing injection? Was the goal systemic effects, scalp/hair-specific effects with localized injection, or wound healing applications? What dosing pattern was used and what was observed?

Melanotan I versus melanotan II selectivity experiences. The receptor selectivity difference between melanotan I (more selective for MC1R) and melanotan II (non-selective across MC1R/MC3R/MC4R/MC5R) drives a real difference in side effect profiles. If a research protocol compared the two (sequentially or in different research arms), what differences were observed? Pigmentation effects, appetite changes, sexual function effects, sebaceous activity changes? Most of the published research is on melanotan I; community-level experience with melanotan II adds to the picture.

PTD-DBM and hair loss research. The published research base on PTD-DBM is younger than on conventional hair loss treatments. If a research protocol used PTD-DBM (alone or in combination with finasteride or minoxidil), what dosing pattern was used, over what timeframe, and what endpoints were tracked? Photographic documentation, hair count measurements, density measurements, subjective assessment? The community has the chance to add to a thinner literature base in this specific area.

Topical formulation considerations. If a research protocol custom-formulated topical GHK-Cu (or another topical peptide), what carrier was used? What pH? Was preservative added or was the formulation made fresh? What stability was observed? Custom topical formulation is one of the more accessible community-research areas because the materials are widely available.

PT-141 protocol experiences. PT-141 has different research applications than the other compounds in this category — sexual function research rather than appearance research. If a protocol used PT-141, what dosing pattern was used (intranasal versus injection), what timing relative to intended effect, what side effect profile was observed?

A note on framing.
This category attracts a wider range of researchers than some other categories — appearance-focused, hair-loss-focused, sexual-function-focused, and wound-healing-focused researchers all share these compounds. Please specify what research context you are operating in when describing protocols. Protocol design choices that make sense in a wound-healing research context may not transfer to a cosmetic appearance research context, and vice versa.

If you have questions but do not want to post them publicly, DMs are open. The thread is the right place for shareable Q&A but private messages work for protocol-specific or vendor-specific questions.