Where the experiments reached
Skin, blood, muscle and brain are different destinations. Comparing the findings means retaining those locations.
Results by location
A single podium seems absurd for compounds being studied for such different problems. The studies asked about different problems and reached different parts of the body. For this comparison, the useful unit is the experimental destination.
| Substance | Location and finding | Human question still open |
|---|---|---|
| GHK-Cu | Copper passed into and through removed human skin. | How does a particular topical formulation change living skin? |
| NAD+ precursors | Oral NMN improved muscle insulin sensitivity in prediabetic women after menopause. | Which tissue changes lead to lasting clinical benefits? |
| BPC-157 | Animal and cell experiments found vascular responses. | Does it improve injury repair with acceptable risk in people? |
| PT-141 | Human trials improved desire and distress scores in premenopausal women with HSDD. | How does the modest average benefit balance against adverse effects for an eligible individual? |
Different observation periods
The BPC-157 elimination half-life under 30 minutes came from rats and dogs. The 48-hour skin experiment followed copper in removed human tissue. The 52-week bremelanotide extension followed women who knew they were receiving active treatment. Each duration concerns a different thing: chemical disappearance, material movement or clinical follow-up.
Transferring any of those intervals to another question would trouble me. A short chemical half-life can coexist with a longer biological response. Long follow-up can reveal tolerability while leaving a placebo comparison unavailable. The time attached to a result has a job of its own.
Clinical status
Bremelanotide has an approved indication with explicit population limits and cardiovascular warnings. BPC-157 is unapproved and prohibited in competitive sport. GHK-Cu has a cosmetic history and no approved systemic drug use. Compounded NAD+ injectables are not FDA-approved.
The human NAD+ review and the BPC-157 review describe very different gaps, while the topical GHK review puts formulation and skin passage close to the centre of its account. The greater volume of bremelanotide research supports a narrower, more specific clinical claim. I regard that precision as an achievement.
For the full source titles, there is a reading list. The compound essays follow the experiments in greater detail.