Overview
Melanotan I is a melanocortin peptide. Linear alpha-melanocyte-stimulating hormone analogue (13 amino acids).
With a half-life of ~30 minutes, Melanotan I requires daily administration in most observed protocols. Administered via SubQ injection, it has a bioavailability of approximately 75% via its primary route.
Half-life approximately 30 minutes. More selective melanocortin receptor binding profile than cyclic analogues. Subcutaneous administration. One-compartment model.
Mechanism of Action
Melanotan I's pharmacological activity involves the following key pathways:
Melanocortin Receptor Activation
Melanotan I binds to melanocortin receptors (particularly MC1R), stimulating melanogenesis — the production of melanin pigment in skin cells.
Melanin Synthesis
Activation of MC1R triggers a cascade that upregulates tyrosinase activity, the rate-limiting enzyme in melanin production.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
0.5 mg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
8-16 weeks
Dose
1.5 mg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
8-16 weeks
Reconstitution Steps
Melanotan I is supplied as a lyophilized (freeze-dried) powder and requires reconstitution before use. Common vial sizes: 5 mg, 10 mg.
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1
Allow Vial to Reach Room Temperature
Allow the lyophilized Melanotan I vial and bacteriostatic water to reach room temperature before opening.
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2
Draw Bacteriostatic Water
Using an insulin syringe, draw up 2.0 mL of bacteriostatic water. For a 10 mg vial this yields 5 mg/mL (5,000 mcg/mL).
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3
Add Water to Vial
Insert the needle through the rubber stopper and angle it so the water stream runs slowly down the inside wall of the vial — do not inject directly onto the powder as this can damage fragile peptide chains.
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4
Gently Swirl to Dissolve
Gently swirl (do not shake) the vial until the powder is fully dissolved into a clear, colourless solution.
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5
Draw Dose and Administer
Draw the required volume for the planned dose into a fresh insulin syringe and administer subcutaneously into a pinched fold of abdominal or thigh skin.
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6
Label and Refrigerate
Label the vial with the reconstitution date and store refrigerated at 2–8°C, protected from light. Use within 4 weeks.
Quick Reconstitution Math
10 mg vial + 2.0 mL BAC water = 5 mg/mL (5,000 mcg/mL). A 1 mg dose = 0.2 mL = 20 units on a U-100 syringe. A 0.5 mg dose = 0.1 mL = 10 units. Use the Milligram reconstitution calculator for custom vial sizes.
Reconstituted Melanotan I is stable for up to 4 weeks refrigerated at 2–8°C. Lyophilized powder should be kept frozen at −20°C until use. Avoid repeated freeze-thaw cycles of the reconstituted solution.
Frequently Asked Questions
What is Melanotan I and how does it produce a tan?
Melanotan I, also known as afamelanotide, is a synthetic linear analogue of alpha-melanocyte stimulating hormone (α-MSH). It works by binding to melanocortin 1 receptors (MC1R) on melanocytes in the skin, activating the cAMP signalling cascade that upregulates the enzyme tyrosinase and shifts melanin production toward eumelanin–the brown/black pigment responsible for tanning. UV exposure is still required to trigger visible darkening, but Melanotan I significantly amplifies the tanning response to the same amount of UV compared with baseline.
How is Melanotan I different from Melanotan II?
Melanotan I is a linear peptide that acts primarily on MC1R, making it more selective than Melanotan II, which additionally activates MC3R and MC4R. This selectivity means Melanotan I produces fewer off-target effects–most notably, it does not typically produce the libido effects, spontaneous erections, nausea, or appetite suppression associated with Melanotan II. Melanotan I also has a shorter half-life than Melanotan II. Afamelanotide (brand name Scenesse) is the only melanocortin peptide approved by the FDA, indicated for erythropoietic protoporphyria (EPP).
What is the half-life of Melanotan I and how often should it be dosed?
Melanotan I has a plasma half-life of approximately 30 minutes via subcutaneous administration, with an absorption phase half-life of 0.07–0.79 hours and a beta-phase half-life of 0.8–1.7 hours. Due to this short half-life, daily or twice-daily subcutaneous administration is commonly observed during the loading phase. The tanning effect persists well beyond the compound's plasma half-life because the downstream melanocyte activation and melanin production continue for days to weeks after each dose.
How long does Melanotan I take to produce visible tanning?
The first signs of pigmentation–subtle darkening of freckles or moles–are often observed within the first 1–2 weeks of use with UV exposure. A noticeable tan typically develops over 4–8 weeks of consistent subcutaneous dosing combined with regular, controlled UV exposure. Significant tanning of the face, arms, and neck has been observed in clinical studies peaking approximately one week after completing a dosing regimen and still present three weeks post-dose. UV exposure is required–Melanotan I loads melanin production capacity but visible darkening depends on UV triggering the oxidation of melanin.
What are the commonly observed side effects of Melanotan I?
Melanotan I has a more selective receptor profile than Melanotan II and is associated with fewer off-target effects. The most commonly observed effects are mild and transient: slight flushing, injection site reactions, and in some cases mild nausea. Because it primarily targets MC1R rather than the appetite and libido-related MC3R/MC4R receptors, spontaneous erections and significant appetite suppression are not typically observed. Darkening of existing moles and freckles is a direct pharmacological effect and is commonly noted during loading.
Does Melanotan I require UV exposure to produce a tan?
Yes. Melanotan I increases melanocyte activity and upregulates melanin production, but it does not produce visible tanning on its own without UV light. It functions as a tan amplifier rather than a self-tanner–UV exposure triggers the oxidation of melanin that produces visible pigmentation. Research protocols have typically involved short, controlled sun or tanning bed sessions of 5–10 minutes during the loading phase. The compound makes the skin more responsive to UV, meaning a deeper tan can be achieved with less total UV exposure compared with baseline.