The ten compounds you'll encounter most, each broken down the way a researcher reads them — mechanism, what it's studied for, evidence tier, and half-life. Descriptive only; no amounts, no protocols.

1 · Semaglutide

GLP-1 analog · metabolic

Mechanism

GLP-1 receptor agonist — slows gastric emptying, signals central appetite centers, regulates insulin and glucagon.

Studied for

Type-2 diabetes and weight management, in large randomized human trials.

Evidence

Strong human — among the most-studied peptides in medicine.

Half-life

~7 days (studied on a weekly cadence); subcutaneous, with an oral form too.

2 · Tirzepatide

Dual GIP/GLP-1 agonist · metabolic

Mechanism

Activates both incretin receptors (GIP + GLP-1) at once — a broader metabolic signal than single agonists.

Studied for

Diabetes and weight; trials showed larger effects than GLP-1-only compounds.

Evidence

Strong human — large published RCT program.

Half-life

~5 days (weekly cadence); subcutaneous.

3 · BPC-157

Regenerative · tissue repair

Mechanism

A synthetic gastric-derived sequence; proposed pro-angiogenic and growth-factor signaling that supports tissue repair.

Studied for

Tendon, ligament, muscle and gut healing — extensively in rodent models.

Evidence

Preclinical — huge reputation, abundant animal data, essentially no controlled human trials.

Half-life

Short in circulation; studied by injection (and orally for gut research).

4 · TB-500 (Thymosin β-4)

Regenerative · tissue repair

Mechanism

An actin-binding thymosin fragment that promotes cell migration and angiogenesis.

Studied for

Wound, muscle and cardiac repair — in animal models.

Evidence

Preclinical — often paired with BPC-157 in the literature.

Half-life

Relatively long for a peptide (days); subcutaneous.

5 · CJC-1295

GHRH analog · GH axis

Mechanism

GHRH-receptor agonist — signals the pituitary to release the body's own GH. The DAC version binds albumin for extended action.

Studied for

GH/IGF-1 elevation and body composition; usually studied alongside a GHRP.

Evidence

Limited human — early pharmacology studies.

Half-life

With DAC ~6–8 days; the no-DAC form is minutes. Subcutaneous.

6 · Ipamorelin

GHRP secretagogue · GH axis

Mechanism

A selective ghrelin-receptor (GHS-R) agonist that triggers a GH pulse with minimal effect on cortisol or prolactin.

Studied for

GH release; the classic partner to a GHRH analog (one signals, one amplifies).

Evidence

Limited human; valued in research for its selectivity.

Half-life

~2 hours; subcutaneous.

7 · GHK-Cu

Copper peptide · skin

Mechanism

A copper tripeptide that delivers copper and stimulates collagen and glycosaminoglycan synthesis; antioxidant and wound-healing signals.

Studied for

Skin regeneration, wound healing and hair — largely topical/dermal.

Evidence

Moderate — one of the more solid non-GLP-1 literatures.

Half-life

Local/topical action; also studied injectable in research.

8 · PT-141 (Bremelanotide)

Melanocortin · sexual function

Mechanism

A melanocortin (MC4R/MC3R) agonist acting on central arousal pathways — a different mechanism from vascular drugs.

Studied for

Sexual dysfunction; the approved drug Vyleesi is bremelanotide.

Evidence

Approved analog — human trial data for HSDD.

Half-life

~2.7 hours; subcutaneous.

9 · MOTS-c

Mitochondrial-derived · metabolic

Mechanism

A mitochondrial-derived peptide that activates AMPK and acts as a metabolic and exercise-mimetic signal.

Studied for

Metabolic health, insulin sensitivity, exercise capacity and aging.

Evidence

Preclinical / early — mechanistically compelling, human data thin.

Half-life

Short; subcutaneous in research.

10 · SS-31 (Elamipretide)

Mitochondrial-targeting · cellular health

Mechanism

A tetrapeptide that binds cardiolipin on the inner mitochondrial membrane, stabilizing it and improving energy transfer while reducing reactive oxygen species.

Studied for

Mitochondrial disease, heart failure and aging models.

Evidence

Some human — the furthest along the frontier list, in clinical development.

Half-life

Short; subcutaneous.

Half-life and route are pharmacokinetic facts as studied — not dosing guidance. Nothing here recommends an amount, a schedule, or use in a person.

The Peptide Playbook.