How long does Afamelanotide stay in your system?
Afamelanotide has a published half-life of approximately 15 hours (apparent). By the standard pharmacology rule of thumb, a drug is about 97% eliminated after roughly five half-lives, which here works out to about 3.1 days. That figure is apparent and release-limited, because afamelanotide is given as a slow-release implant.
Source: Scenesse label, DailyMed · FDA label · measured: subcutaneous controlled-release implant · dataset reviewed September 23, 2026
What is the half-life of Afamelanotide?
The Scenesse prescribing information gives afamelanotide an apparent half-life of approximately 15 hours. Afamelanotide, historically known as Melanotan I, is an analogue of alpha-melanocyte-stimulating hormone, and it is approved as a subcutaneous controlled-release implant for erythropoietic protoporphyria, a rare inherited condition that causes severe pain on exposure to light.
The word apparent is doing real work. The implant releases drug gradually, with a median time to peak concentration of 36 hours, so the decline measured in blood is limited by how fast the implant releases afamelanotide, not only by how fast the body clears it. Amino acid substitutions also make afamelanotide more resistant to enzymatic breakdown than native alpha-MSH.
How much Afamelanotide is left after each half-life?
Each half-life removes half of whatever is left, so the percentages are pure arithmetic and the same for any compound; only the clock changes. For Afamelanotide, one half-life is 15 hours. The rows below run that forward for a single amount with nothing added.
| Half-lives elapsed | Time elapsed | Remaining | Cleared |
|---|---|---|---|
| 1 | 15 hours | 50% | 50% |
| 2 | 30 hours | 25% | 75% |
| 3 | 45 hours | 12.5% | 87.5% |
| 4 | 60 hours | 6.25% | 93.75% |
| 5 | 3.1 days | 3.13% | 96.88% |
| 6 | 3.8 days | 1.56% | 98.44% |
| 7 | 4.4 days | 0.78% | 99.22% |
Why do the numbers differ between sources?
The most common confusion is between the half-life and the implant's duration. The implant's clinical duration of about two months is a property of the delivery system and is unrelated to the 15 hour figure. One describes how long a release device keeps working; the other describes how concentration falls once drug is in the blood.
Figures for Melanotan I from non-label sources deserve caution, and figures for melanotan II do not apply at all. Melanotan II is a different peptide with no published human half-life in our dataset.
What does a half-life not tell you?
For an implant, the five half-life rule does not answer 'how long does it stay in your system'. The table models a quantity already in the blood decaying with nothing added. It does not model a device that keeps releasing drug, so it cannot tell you how long afamelanotide is present after an implant is placed.
It also does not describe pigmentation. Afamelanotide works by stimulating eumelanin production in the skin through MC1R, and that pigment is a tissue change that persists on its own timescale, independent of plasma levels.
Can you run the numbers yourself?
The estimator applies the same decay arithmetic to any half-life, starting amount and time you enter. It opens with Afamelanotide's published value loaded. Type another figure to see how sensitive the result is to it.
Published value: Approximately 15 hours (apparent) (Subcutaneous controlled-release implant) · Scenesse label, DailyMed · Compound profile
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What are the limits of this estimate?
Everything above is a single-compartment approximation: one pool of drug, falling by the same fraction in every interval. Real elimination varies with kidney and liver function, body composition, formulation and route, and a published figure describes only the route and the people it was measured in. Many compounds also show a fast distribution phase before the slower elimination the table describes.
A half-life is not a dosing schedule. Labelled intervals come from clinical trials that measured outcomes and tolerability, and nothing on this page suggests when to take, repeat or stop anything. Whether Afamelanotide is out of your system for drug-testing purposes is a different question again. Tests often look for metabolites rather than the parent compound, and the answer depends on the assay, its sensitivity and the sample type, none of which a plasma half-life captures.
FAQ.
Why does the Scenesse implant last much longer than 15 hours?
Because the implant is a controlled-release delivery system. The label's apparent half-life of approximately 15 hours describes how concentration declines in the blood, limited by release from the implant. The implant's clinical duration of about two months is a property of the device and is unrelated to that figure.
Is afamelanotide the same as Melanotan I?
Afamelanotide is the approved drug historically studied under the name Melanotan I. The half-life on this page comes from the Scenesse label and describes the approved implant. Injectable tanning products sold under Melanotan names are not the approved product and have not been characterised the same way.
Does this apply to melanotan II?
No. Melanotan II is a different peptide. Our half-life reference records no reliable human pharmacokinetic data for it, only a rat study, so there is no human figure to quote.
For what the evidence on Afamelanotide actually shows, read the Afamelanotide profile. For approval and regulatory position, see is Afamelanotide legal. The half-life reference lists every sourced value side by side, including the compounds where a number circulates online with no reliable human data behind it.