Melanotan I Calculator

What Is Melanotan I?

Melanotan I, known in the scientific literature as afamelanotide, is a synthetic linear tridecapeptide and a structural analog of alpha-melanocyte-stimulating hormone (alpha-MSH). Alpha-MSH is a naturally occurring messenger from the melanocortin family that, among other functions, regulates the production of skin pigment. The native hormone is broken down very rapidly by enzymes in the body, which makes it impractical for studying its effects in any sustained way. Melanotan I was developed in the 1980s at the University of Arizona as a stabilized variant: by selectively substituting individual amino acids, researchers produced a molecule that resists enzymatic degradation far better and remains in circulation longer than the native hormone.

The defining difference from its better-known relative, Melanotan II, is receptor selectivity. Melanotan I acts predominantly and comparatively selectively at the melanocortin-1 receptor (MC1R), the receptor subtype responsible for skin pigmentation. Melanotan II, by contrast, is a pan-agonist that additionally engages receptors in the central nervous system, producing effects such as appetite suppression and sexual arousal. This selectivity gives Melanotan I the profile that characterizes it in research: a melanocortin peptide focused on melanogenesis with markedly fewer central nervous system side effects.

Melanotan I is not an approved drug and is sold strictly as a substance for research purposes. The structurally related compound afamelanotide has received regulatory approval in some jurisdictions for a rare light-intolerance condition, but the freely reconstitutable research peptide described here should be considered separately from that. Robust long-term human data on Melanotan I as a research substance is largely lacking, so all consideration of it remains within the research domain.

Mechanisms of Action

Melanotan I exerts its effects exclusively through activation of melanocortin receptors, a family of G-protein-coupled receptors. Unlike the non-selective Melanotan II, the activity of Melanotan I is largely concentrated on a single subtype, which makes its effect profile more focused and predictable:

• Selective MC1R agonism: Melanotan I binds preferentially to the melanocortin-1 receptor, which is located on the melanocytes of the skin. This comparatively selective binding is the central distinguishing feature relative to Melanotan II and substantially reduces the extent of central nervous system effects.
• Stimulation of melanogenesis: Activation of MC1R increases the activity of tyrosinase, the rate-limiting enzyme of pigment synthesis. This in turn drives the production of melanin within the melanocytes.
• Shift toward eumelanin: Melanotan I shifts the ratio of pigments produced from reddish-yellow pheomelanin toward dark brown to black eumelanin. Eumelanin absorbs UV radiation more efficiently, which is why this mechanism is of particular interest in research.
• UV-independent pigmentation: Because Melanotan I stimulates melanocytes directly through the receptor, a deepening of skin pigmentation can in principle be triggered without prior UV exposure. This was the original research rationale behind the development of the Melanotan series.
• Low MC3R, MC4R, and MC5R activity: Unlike Melanotan II, Melanotan I engages the remaining melanocortin receptors only to a small degree. As a result, appetite-suppressing and pro-erectile effects, along with the associated nausea, are markedly weaker.
• Anti-inflammatory properties: Melanocortins generally possess inflammation-modulating effects. In Melanotan I, however, this component is far less characterized than the pigmenting effect and rarely takes center stage in research practice.

Dosage Calculation

Compared to Melanotan II, Melanotan I acts more slowly and more mildly, which calls for a slightly more patient research plan. Because it stimulates the melanocytes directly, it is common to begin at the lower end of the dosing range, observe the response, and only then adjust the dose gradually.

Standard Dosing Parameters

• Starting / loading dose: 0.1 mg (100 mcg) per administration
• Standard dose: 0.25 mg (250 mcg) per administration
• Higher range: 0.5–1.0 mg (500–1,000 mcg) per administration
• Frequency: Often daily during the loading phase, typically every other day during maintenance
• Half-life: Approximately 1 hour (literature estimate), shorter than Melanotan II
• Typical syringe: 0.3 mL insulin syringe (29–31 gauge, 6–8 mm needle)

Example Calculation: 10 mg Vial with 2 mL BAC Water

A common vial size is 10 mg. Adding 2 mL of bacteriostatic water gives a concentration of 5 mg/mL (5,000 mcg/mL).

• 0.10 mg dose: 100 ÷ 5000 = 0.02 mL (2 units on a U100 syringe)
• 0.25 mg dose: 250 ÷ 5000 = 0.05 mL (5 units)
• 0.50 mg dose: 500 ÷ 5000 = 0.10 mL (10 units)
• 1.00 mg dose: 1000 ÷ 5000 = 0.20 mL (20 units)

At a standard dose of 0.25 mg, a 10 mg vial provides 40 administrations. The very small volumes at low doses are difficult to read precisely on an insulin syringe. It can therefore make sense to use more BAC water to lower the concentration and increase the readable volume. Use the Melanotan I calculator above to compute exact volumes and units for any vial size, reconstitution volume, and target dose.

Reconstitution

Melanotan I is supplied as a lyophilized (freeze-dried) powder in sealed vials and must be reconstituted with bacteriostatic water (BAC water) before use. BAC water contains 0.9% benzyl alcohol, which inhibits microbial growth and extends the usable window of the dissolved solution. Sterile water for injection is less suitable for multi-dose vials because it contains no preservative.

Step-by-Step Reconstitution Protocol

1. Gather supplies: Melanotan I vial, bacteriostatic water vial, alcohol swabs, a sterile draw needle (18–21 gauge), and your insulin syringe for administration.
2. Wipe the rubber septa of both vials with fresh alcohol swabs. Allow to air-dry for 30 seconds. Do not blow on the septa or touch them after cleaning.
3. Draw the desired volume of BAC water (2 mL is standard for a 10 mg vial) into the draw syringe.
4. Insert the needle into the peptide vial at an angle, directing the tip toward the inner glass wall rather than the lyophilized powder. A direct stream onto the powder cake can shear peptide bonds and damage the molecule.
5. Slowly push the plunger, allowing BAC water to run down the inside wall of the vial and gently contact the powder from below.
6. Gently swirl or roll the vial between your palms until the powder is completely dissolved. The solution should appear clear and colorless. Do not shake or vortex the vial.
7. Label the vial with the reconstitution date and concentration (e.g., "Melanotan I 5 mg/mL — reconstituted [date]").

If the solution appears cloudy, discolored, or contains visible particulate matter, discard the vial and do not use it.

Storage and Shelf Life

• Lyophilized powder (unreconstituted): Store at −20°C for long-term storage (stable for 24+ months). Short-term storage at 2–8°C (refrigerator) is acceptable for up to 3 months. Keep away from light and moisture.
• Reconstituted solution: Store in the refrigerator at 2–8°C, stable for approximately 28–30 days. Keep the vial upright and away from light, and discard after 30 days regardless of remaining volume.
• Do not freeze reconstituted peptide. Freeze-thaw cycles cause aggregation and loss of activity. Once reconstituted, the vial must remain refrigerated throughout its use window.
• Light protection: Like other melanocortin peptides, Melanotan I is light-sensitive. Store the vial in the dark and avoid prolonged exposure to direct light.
• Transport: Use an insulated cooler with an ice pack for any travel lasting more than 1–2 hours. Commercial insulated medication pouches maintain 2–8°C for 24–48 hours. Avoid exposure to temperatures above 25°C during transport.

Side Effects and Safety Profile

Melanotan I is regarded in research as the more tolerable melanocortin peptide compared to Melanotan II because of its receptor selectivity. Since it engages central nervous system receptors only minimally, nausea, appetite suppression, and spontaneous erections occur less frequently and less intensely. Nevertheless, Melanotan I is not free of risk, and robust long-term human data is lacking.

Commonly Reported Observations

• Mild nausea, primarily in the first few days or after a dose increase. It is usually weaker than with Melanotan II and tends to subside as use continues.
• Transient facial flushing shortly after administration, which typically resolves within a short time.
• Increased pigmentation of moles, freckles, and new pigment spots. This is the most closely watched safety-relevant observation across the entire Melanotan series.
• Mild irritation, redness, or brief discomfort at the injection site, which can be minimized by rotating injection sites.

Less Common or Theoretical Concerns

• Changes to skin lesions: Because Melanotan I directly stimulates melanocyte activity, research discusses whether existing moles may darken or new pigmented lesions may appear. Dermatological monitoring is considered important in a research context.
• Contamination risk from unverified sources: Several documented incidents around the Melanotan series relate to unverified material of unknown purity rather than to the molecule itself. The purity and identity of the material are therefore of high importance.
• Circulatory effects: Although weaker than with Melanotan II, a mild transient drop in blood pressure can occur and may be relevant for individuals prone to hypotension.

Contraindications

• History of melanoma or other skin cancer, as well as a high number of atypical moles
• Pregnancy and breastfeeding (insufficient safety data)
• Known cardiovascular disease or pronounced hypotension
• Known hypersensitivity to any component of the preparation

Consultation with a qualified physician is strongly recommended, particularly because of the dermatological safety considerations associated with the entire Melanotan series.

Combinations and Stacks

Melanotan I and Melanotan II

In research, Melanotan I is most often compared directly with Melanotan II. Both peptides stimulate melanogenesis through MC1R, but their profiles differ markedly. Melanotan II is a pan-agonist that acts faster and more strongly but brings pronounced central nervous system side effects. Melanotan I acts more selectively, more slowly, and more mildly. A true simultaneous combination of the two substances is uncommon, since their pigmentation pathways overlap and effects become hard to attribute. The more relevant choice is a deliberate decision between potency (Melanotan II) and selectivity (Melanotan I).

Melanotan I and PT-141

PT-141 (bremelanotide) is also a melanocortin peptide, but it focuses on the central nervous system MC3R/MC4R effects around sexual arousal and produces little pigmentation. Where Melanotan I specifically targets MC1R-mediated melanogenesis, PT-141 addresses a different endpoint of the melanocortin family. A combination is unusual in research, since the two engage overlapping receptors and their circulatory effects could compound. The comparison mainly illustrates how very differently oriented analogs were developed from the same receptor family.

Melanotan I as a Standalone

Because of its focused effect profile, Melanotan I is almost always considered a standalone substance in research practice. Since its mechanism is tightly limited to MC1R, combining it with other peptides mainly adds complexity without extending the pigmentation-related endpoint. For those who want to compare the peptide with its closely related but more potent counterpart, detailed information is available on the Melanotan II calculator page.

Frequently Asked Questions

How does Melanotan I differ from Melanotan II?

The central difference is receptor selectivity. Melanotan I acts comparatively selectively at the melanocortin-1 receptor and therefore produces mainly pigmentation, with only minor central nervous system effects. Melanotan II is a pan-agonist that additionally activates MC3R and MC4R, which makes it stronger, faster, and accompanied by more pronounced side effects such as nausea, appetite suppression, and sexual arousal. Melanotan I is regarded as more tolerable, Melanotan II as more potent.

Does Melanotan I work without sun exposure?

Melanotan I stimulates melanocytes directly through MC1R and can in principle deepen pigmentation independently of UV. However, the research literature describes that moderate UV exposure can accelerate visible pigmentation because it triggers additional melanocyte activity. Excessive UV exposure is not advisable and conflicts with a careful research approach.

Why does Melanotan I act more slowly than Melanotan II?

Melanotan I has a shorter estimated half-life of about one hour and engages essentially only MC1R. Melanotan II activates several receptors simultaneously and is regarded as a superpotent pan-agonist, which is why visible effects emerge faster. The slower kinetics of Melanotan I mean a research plan requires more patience, but it comes with less pronounced side effects.

Why don't IU match the milligram dose?

The IU scale on an insulin syringe is a pure volume scale: 1 IU equals 0.01 mL. How much mass sits in that volume depends entirely on the concentration of the dissolved solution. At 5 mg/mL, 5 IU contain exactly 0.25 mg of peptide. The calculator translates your target dose in milligrams into the corresponding volume and the units to read off.

Does Melanotan I cause nausea?

Nausea is markedly less frequent and weaker with Melanotan I than with Melanotan II because central nervous system melanocortin receptors are barely activated. It is most likely to appear at the start or after a dose increase and usually subsides as use continues. A low starting dose and a slow escalation are the most effective measures.

Is Melanotan I an approved drug?

The research peptide described here is not approved as a drug and is sold strictly as a substance for research purposes. The structurally related compound afamelanotide has received regulatory approval in some countries for a narrowly defined medical indication, but that should be considered separately from a freely reconstitutable research peptide.

How does Melanotan I affect moles?

Because Melanotan I directly increases melanin production, existing moles, freckles, and pigment spots can appear darker, and new pigment spots may become visible. This is the most frequently cited safety-relevant observation. Regular dermatological monitoring is considered important in a research context.

How long does a Melanotan I protocol last?

In research practice, a loading phase with low, often daily doses is used first, until a target pigmentation level is reached. A maintenance phase with less frequent administration follows, typically every other day. Because of the slower kinetics, the loading phase can take several weeks. Exact volumes are most accurately determined with the calculator above.

Medical Disclaimer: The information on this page is provided for educational and research purposes only. Melanotan I is not an approved drug or medical treatment and is sold strictly for research use. Nothing on this page constitutes medical advice, diagnosis, or a recommendation to use any specific compound. Always consult a qualified healthcare professional before beginning any peptide protocol. BergdorfBio assumes no liability for the use or misuse of the information presented here.