Afamelanotide: What It Is and How the Scenesse Implant Works

At a glance

What is afamelanotide?

Afamelanotide is a synthetic peptide that mimics alpha-melanocyte-stimulating hormone (α-MSH), the natural hormone that controls skin pigmentation. It is an analog engineered to be more potent and far longer-lasting than natural α-MSH, and it is also known by the research names Melanotan I and NDP-MSH. It is made by Clinuvel Pharmaceuticals and sold as Scenesse. Rather than a daily injection, it is given as a small dissolvable implant placed just under the skin by a healthcare provider, which releases the drug slowly over several days.

The history of afamelanotide

Afamelanotide began as an attempt to bottle a sunless tan. In the 1980s, researchers Mac Hadley and Victor Hruby at the University of Arizona set out to design a synthetic version of α-MSH that could darken skin without sun exposure, reasoning that a drug-induced protective tan might lower skin cancer risk in a sun-drenched state like Arizona. Natural α-MSH breaks down too quickly to be practical, so they built a more stable, more potent analog and called it Melanotan. The Arizona program actually produced two related compounds. Melanotan I, the linear analog, is what became afamelanotide. A second, cyclic analog called Melanotan II was pursued separately and eventually led to a different drug for sexual dysfunction. The program then shifted from a cosmetic tanning agent to a medical photoprotectant for people with serious light-sensitivity disorders. That path led, over roughly two decades, to approval for erythropoietic protoporphyria (EPP), in the European Union in 2014 and the United States in 2019. The original tanning idea never fully went away. Unapproved "Melanotan I" and "Melanotan II" peptides are still sold online as injectable tanning products, and regulators have repeatedly warned against them, because they are not approved, not quality-controlled, and not the same as the regulated implant.

How does afamelanotide work?

Afamelanotide works by switching on the skin's own pigment system to build a protective layer of melanin. It is a potent agonist of the melanocortin-1 receptor, or MC1-R, which sits on melanocytes, the pigment-producing cells of the skin. Activating MC1R drives those cells to make more eumelanin, the dark form of melanin that acts as the body's natural sunscreen, absorbing and scattering light and neutralizing the reactive oxygen species that light can generate in the skin. Because the drug triggers this through the receptor rather than through sun exposure, it raises eumelanin without requiring the UV damage that normally produces a tan. In erythropoietic protoporphyria, that extra pigment matters for a specific reason. People with EPP build up a molecule called protoporphyrin IX, which reacts with visible light to produce bursts of reactive oxygen that damage tissue and cause severe burning pain after even brief light exposure. By increasing eumelanin, afamelanotide reduces how much light reaches and reacts in the skin, which lengthens the time a person can spend in the light before pain begins. The pharmacology explains the delivery form. The peptide is far more stable than natural α-MSH, so it is delivered as a bioresorbable implant that releases it over days. Two placebo-controlled pivotal trials, reported together in 2015, enrolled 168 adults with EPP. The table shows their results beside a later real-world cohort:

The most common adverse events in the pivotal trials were headache, nausea, nasopharyngitis, and back pain, and quality of life improved in both studies.

Is it FDA-approved?

Yes. The FDA approved afamelanotide in October 2019 as Scenesse, the first treatment in the United States shown to increase pain-free light exposure in adults with a history of phototoxic reactions from erythropoietic protoporphyria. It had already been approved in the European Union in 2014. It remains the only FDA-approved drug that works by stimulating melanin for photoprotection.

What is afamelanotide prescribed for?

Afamelanotide is prescribed for adults with erythropoietic protoporphyria to increase the amount of time they can spend in the light without pain. EPP is a rare inherited disorder in which light exposure causes severe burning pain in the skin, which sharply limits daily life. Consensus guidelines from 2023 recommend afamelanotide for preventing phototoxic symptoms in EPP. It is not a cosmetic tanning product and is not approved for tanning or for any other condition. Because it is an implant, it is administered by a healthcare provider rather than self-injected. The label advises a full-body skin examination twice a year, since the drug increases pigmentation and can darken existing moles, which makes routine skin monitoring important.

What are the side effects?

According to the prescribing information, the most common side effects are:

• Implant-site reactions
• Nausea
• Throat pain and cough
• Fatigue
• Skin hyperpigmentation and darkening of existing moles
• Dizziness or drowsiness
• Respiratory tract infection
• Skin irritation The label also warns that serious hypersensitivity reactions, including anaphylaxis, have been reported with postmarket use.

Because afamelanotide increases skin pigmentation, the label calls for regular full-body skin exams so that moles and any suspicious lesions can be monitored over time.

Evidence strength

FDA approved: It is approved by the FDA for erythropoietic protoporphyria, backed by two multicenter, randomized, double-blind, placebo-controlled trials showing increased pain-free light exposure.

Sources: FDA prescribing information for Scenesse (afamelanotide); the pivotal randomized controlled trials in the New England Journal of Medicine (Langendonk et al., 2015, DOI: 10.1056/NEJMoa1411481), indexed on PubMed; and FDA and published histories of the compound's development. This document is educational and does not constitute medical advice.