Comparison
Afamelanotide vs. Linaclotid
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Research other
Research other
CAS no.
75921-69-6
851199-59-2
Molecular weight
1646.87 g/mol
1526.74 g/mol
Half-life
12 h
no data
Sequence
Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2no data
Mechanism of action
Afamelanotide
Afamelanotide is a synthetic analogue of α-melanocyte-stimulating hormone. It differs from native α-MSH by two substitutions — norleucine at position 4 and D-phenylalanine at position 7 — which make it metabolically more stable and more potent. As an agonist at the melanocortin-1 receptor (MC1R) on melanocytes, it activates adenylate cyclase, raises cAMP and increases tyrosinase activity via the transcription factor MITF. This shifts pigment synthesis toward eumelanin, which absorbs UV and visible light and has antioxidant properties — the presumed mechanism of photoprotection in EPP.
Linaclotid
Linaclotide activates the guanylate cyclase-C receptor on the luminal surface of the intestinal epithelium. This raises cyclic GMP (cGMP), increases secretion of chloride and bicarbonate into the lumen, raises stool fluid content and accelerates transit; pain signaling is also modulated.
Evidence base
Highest evidence
Human RCT
Human RCT
Studies
4
0
of which in humans
4
0
Effects recorded
4
2
Open conflicts
1
0
Documented adverse events
4
1
Legal status
Full entries
Frequently asked questions
- What is the difference between Afamelanotide and Linaclotid?
- Afamelanotide is classified as "Research other", while Linaclotid is classified as "Research other". Afamelanotide: Afamelanotide (brand name Scenesse) is a synthetic 13-amino-acid analogue of α-melanocyte-stimulating hormone (α-MSH) and a melanocortin-1 receptor agonist. Unlike most peptides covered here, it is a regularly approved medicine: EMA approval in 2014/2015, FDA approval in 2019, in each case as a subcutaneous implant for the prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP). It promotes eumelanin formation in the skin. Linaclotid: Linaclotide is a 14-amino-acid peptide and guanylate cyclase-C (GC-C) agonist. It is approved for irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC). This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, Afamelanotide or Linaclotid?
- The highest available evidence level is "Human RCT" for Afamelanotide and "Human RCT" for Linaclotid. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of Afamelanotide and Linaclotid in Germany and the United States?
- Germany: Afamelanotide — Prescription, Linaclotid — Prescription. United States: Afamelanotide — Prescription, Linaclotid — Prescription. These are factual summaries with source and review date on the individual pages.