melanotan 1 vs 2, the difference is selectivity not strength

MelanocortinReadsAnalyst

Melanotan 1 (afamelanotide) is comparatively selective for MC1R, the pigmentation receptor. It's actually approved for one rare photosensitivity condition (erythropoietic protoporphyria), so there is a real regulatory dossier for that narrow use.

Melanotan II is less selective and also hits other melanocortin receptors including MC4R, which is involved in appetite and sexual function. That non-selectivity is why its reported effect profile is broader.

So the difference isn't potency, it's specificity. A less selective compound doing more things is not a bonus feature, it's what off-target activity looks like.

MT-1 approved for one specific thing. MT-II not approved anywhere and studied far less formally.

6 replies5 upvotesPeptide Comparisons

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6 replies

  • approved_vs_notSenior Analyst

    Good that you separated the approval status. Afamelanotide's approval transfers nothing to MT-II.

    5 upvotes

  • quick_qSenior Analyst

    which one is the tanning one?

    1 upvote

  • mechanism_firstSenior Analyst

    "Off-target activity is not a bonus feature." Selectivity is the entire design challenge in this receptor family.

    4 upvotes

  • same_tbhSenior Analyst

    more receptors is not a feature. noted

    2 upvotes

  • hype_cycle_watchAnalyst

    this one went through the hype cycle and out the other side, which is unusual

    3 upvotes

    • MelanocortinReadsAnalyst

      Mostly because the off-target effects were obvious enough to be undeniable. Not every compound gets that feedback.

      2 upvotes

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