Research Peptide Fundamentals
Compare these peptides
Five compounds, five different evidence profiles. Here is the honest side-by-side.
The short version
These five compounds are discussed together because they appear in the same communities and research conversations — but they are meaningfully different in what they are, how much human evidence exists, and what regulators have said about them. The table below captures the key dimensions. The key takeaway: only PT-141 (bremelanotide) has completed the drug-approval process for a specific indication. Retatrutide is in Phase 3 trials. BPC-157 and ipamorelin have no approved use. NAD+ is a supplement in an entirely different regulatory category.
Side-by-side comparison
| Compound | Class | Primarily studied for | Human evidence maturity | Regulatory status | WADA |
|---|---|---|---|---|---|
| Retatrutide [1][4] | Investigational GIP/GLP-1/glucagon triple agonist | Obesity, type 2 diabetes, MASLD (liver fat) | Multiple Phase 2 RCTs; Phase 3 ongoing (TRIUMPH) | INVESTIGATIONAL — not approved anywhere | Not specifically prohibited; athletes check current WADA list |
| BPC-157 [8][9] | Synthetic pentadecapeptide (cytoprotective) | Tissue repair (tendons, gut, bone) in animal models; gastric protection | Mostly preclinical; 2–3 small human pilot reports; no large RCTs | Not approved; not eligible for 503A compounding (FDA) | Prohibited at all times (S0, non-approved substances) |
| Ipamorelin [15][16] | GHS-R1a agonist (growth hormone secretagogue) | GH release, postoperative ileus (Phase 2 — failed endpoint) | 1 Phase 2 RCT (failed); 1 human PK/PD study | Not approved; removed from 503A compounding list (2024) | Prohibited at all times (S2, growth hormone secretagogues) |
| PT-141 [20][22] | Melanocortin MC4R/MC3R agonist (cyclic heptapeptide) | Hypoactive sexual desire disorder (HSDD) in premenopausal women | Phase 3 RCTs (2019); 52-week extension; fMRI mechanistic study | FDA-APPROVED (HSDD in premenopausal women only); all else off-label | Non-approved in non-indicated contexts (S0); consult current WADA guidance |
| NAD+ [23][26] | Endogenous redox coenzyme / dietary supplement | Aging, energy metabolism, insulin sensitivity, DNA repair | Dose-response RCTs for NAD+ elevation; limited hard clinical-endpoint trials | Dietary supplement (US); compounded injectable subject to FDA oversight | Not prohibited |
Reading the comparison honestly
A few points to hold alongside the table:
Evidence maturity is not the same as efficacy. PT-141 has the most mature human evidence, but its approved effect — improved sexual desire in women with HSDD — was modest in absolute magnitude in the RECONNECT trials [20]. More evidence does not mean stronger effects.
Retatrutide's Phase 2 numbers are striking, but Phase 3 is where drugs live or die. The −24% weight loss at 48 weeks in a Phase 2 population [4] is the most dramatic number on this desk. It also has the largest human evidence base of the non-approved compounds — but the TRIUMPH Phase 3 program is what will determine whether it reaches patients.
BPC-157 has the largest animal-study database but the thinnest human evidence. The mismatch between the rich preclinical literature and the tiny number of human participants studied is the central issue with BPC-157 [9]. That gap makes it a poor basis for conclusions about human efficacy or safety.
Ipamorelin's Phase 2 failure matters. The null result in the postoperative ileus trial [15] is frequently omitted from wellness promotion. It does not mean ipamorelin is inert — but it means the drug-development path failed at the first human efficacy test.
NAD+ is in a different regulatory category than the others. It is not a drug, not an investigational compound, and not prohibited in sport. The supplement framing, however, also means less rigorous manufacturing oversight and more variable product quality.