Peptides vs SARMs : fundamental differences in research
Peptides and SARMs are two categories of research compounds that are often confused. However, their chemical nature, mechanisms of action, biological targets, and safety profiles are radically different. This guide clarifies the essential distinctions for researchers.
Fundamental chemical nature
The first distinction is structural:
- Peptides These are chains of amino acids (2 to 50 AA) linked by peptide bonds. They are biomolecules, often derived from natural human sequences. They act by mimicking or modulating endogenous signals.
- SARMs (Selective Androgen Receptor Modulators): small synthetic, non-peptide organic molecules. Structurally related to steroids but designed for tissue selectivity on the androgen receptor (AR).
Comparative Mechanisms of Action
Peptides: diversity of targets
The research peptides act on a multitude of receptors and pathways biological:
| Peptide class | Target | Examples |
|---|---|---|
| GH secretagogues | GHS-R1a (ghrelin-R) | Ipamorelin, GHRP-6 |
| GHRH Analogues | GHRH-R | CJC-1295, Tesamorelin |
| GLP-1 Agonists | GLP-1R | Semaglutide, Retatrutide |
| Tissue repair | NO/VEGF/EGF-R | BPC-157, TB-500 |
| Melanocortins | MC3R/MC4R | PT-141 |
| Nootropics | GABA/BDNF/TrkB | Selank, Semax |
SARMs: a single target
All SARMs target the androgen receptor (AR), a nuclear receptor of the steroid receptor superfamily:
- Binding to the ligand-binding domain (LBD) of the AR receptor
- Induction of a specific conformational change (different from testosterone)
- Selective recruitment of co-activators according to tissue type (muscle vs prostate)
- Transcriptional activation of androgen-dependent target genes
Systematic comparison
| Criteria | Peptides | SARMs |
|---|---|---|
| Chemical nature | Amino acid chains | Small organic molecules |
| Molecular mass | 400 – 5000 Da | 300 – 500 Da |
| Administrative route | SC, intranasal, topical | Oral (mostly) |
| Biological target | Multiple (depending on the peptide) | Androgen receptor (AR) |
| Mechanism | Agonist/modulator of membrane or nuclear receptors | Selective AR Modulator |
| Effect on the HPTA axis | None (except GnRH peptides) | Suppressive (dose-dependent) |
| Hepatotoxicity | None documented | Documented for some (RAD-140, S-23) |
| Oral bioavailability | Low (except for exceptions: Semaglutide, BPC-157) | Elevated (designed for oral use) |
| Degradation | Enzymatic (proteases) | Hepatic (CYP450) |
| Regulatory status | Some approved (Semaglutide, Tesamorelin) | None clinically approved |
Security profiles
Peptides: generally favorable profile
- Degradation into natural amino acids (non-toxic metabolites)
- No hepatotoxic metabolites
- No suppression of the hypothalamic-pituitary axis (except in specific cases)
- Side effects are generally reversible and dose-dependent.
- No long-term tissue accumulation
SARMs: documented risks
- Removal of the HPTA axis : decrease in endogenous testosterone, LH and FSH (dose and duration dependent)
- Hepatotoxicity : documented elevation of transaminases, reported cases of cholestasis
- Lipid profile : significant decrease in HDL cholesterol in clinical studies
- Unknown metabolites Phase I and II metabolites are not always characterized.
- Risk of contamination : the market for SARMs has a falsification/contamination rate exceeding 50% according to independent analyses
Research contexts
| Research objective | Peptides | SARMs |
|---|---|---|
| Body composition | GLP-1 agonists, GH secretagogues | Ostarine, LGD-4033 |
| Tissue repair | BPC-157, TB-500, GHK-Cu | Not applicable |
| Cognition / neuroprotection | Selank, Semax, NAD+ | Not applicable |
| Cellular longevity | Epithalon, WORDS-c | Not applicable |
| Muscle anabolism | Indirect (GH/IGF-1) | Direct (rear lane) |
| Bone density | GH secretagogues | Ostarine (Phase II data) |
Peptides and SARMs are not interchangeable and do not target the same biological pathways. The choice depends entirely on the research question. MyPeptide focuses exclusively on HPLC-certified research peptides.
Summary of key differences
- Structure biomolecules (peptides) vs synthetic small molecules (SARMs)
- Targets Multiple receptors (peptides) vs. single AR receptor (SARMs)
- Administration : injectable/intranasal (peptides) vs oral (SARMs)
- Security : natural metabolites (peptides) vs possible hepatotoxicity (SARMs)
- Hormonal axis preserved (peptides) vs suppressed (SARMs)
- Approvals Several approved peptides vs. no approved SARMs
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