RESEARCH USE ONLY. Reference data for laboratory research. Not medical advice; not for human consumption.
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PT-141 vs Melanotan II

A metabolite turned medicine versus its parent compound: same receptor family, different selectivity.

Research use only. A summary of published literature for educational reference — not medical advice and not a guide to human use.

The short version

Melanotan II is a broad melanocortin agonist first studied for skin tanning. PT-141 (bremelanotide) is its metabolite, more selective for MC3/MC4 receptors, and is FDA-approved for a specific sexual desire disorder in premenopausal women.

At a glance

PT-141ProtocolMelanotan IIProtocol

Structure

Cyclic heptapeptide (metabolite of MT-II)

Cyclic heptapeptide α-MSH analog

Receptors

Mainly MC4 and MC3

MC1, MC3, MC4 and MC5

Approval status

FDA-approved (Vyleesi, 2019)

Not approved anywhere

Notable effects studied

Sexual desire endpoints

Skin pigmentation, sexual function

Research vial sizes

10 mg

10 mg

01How they work

Both activate melanocortin receptors. Melanotan II's MC1 activity drives melanin production, which explains tanning. PT-141 lacks the carboxyl-terminal amide and acts mainly on central MC4 receptors involved in sexual motivation.

02What studies measured

The RECONNECT phase 3 trials of bremelanotide reported small but significant improvements in desire and distress scores versus placebo. Early Melanotan II studies reported increased skin pigmentation and erectile responses in small cohorts.

03Reported side effects

Bremelanotide trials most often reported nausea, flushing and headache, plus transient blood-pressure rises. Melanotan II case reports describe nausea, new or changing moles, and other unregulated-use problems.

04Approval & evidence status

PT-141 is approved for one narrow indication. Melanotan II has no approval and regulators in several countries have warned against it.

Citations

  1. [1]Phase 3 randomized controlled trials2019

    Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials

    Kingsberg SA, et al. Obstet Gynecol, 2019.

    Read paper ↗
  2. [2]Phase 1 pilot study1996

    Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study

    Dorr RT, et al. Life Sci, 1996.

    Read paper ↗
Open side-by-side compare →PT-141 referenceMelanotan II referenceCalculator

Research use only. A summary of published literature for educational reference — not medical advice and not a guide to human use.