Melanotan II Pharmacokinetics
Melanotan II half-life, absorption, routes of administration, and clearance.
Half-Life & Dosing Cadence
Melanotan II has a reported elimination half-life of ~33 hours. The half-life is the time it takes for blood levels to fall by half, and it's the single biggest driver of how often you dose. That's why the typical schedule lands around as needed (loading then maintenance) at 250–500 mcg — frequent enough to keep levels in a useful range without stacking up. Shorter half-lives mean more frequent dosing and faster clearance if you stop; longer ones mean steadier levels but a slower washout.
Administration & Absorption
Melanotan II is administered by subcutaneous injection (into the fat layer just under the skin). The primary route is subcutaneous. Subcutaneous delivery is absorbed steadily from the fat depot, giving smoother peaks than intramuscular dosing. Whichever route you use, rotate sites and follow sterile technique.
Reconstitution & Handling
Melanotan II ships as a lyophilized (freeze-dried) powder that you reconstitute before use — a common starting point is a 10 mg vial with 2 mL of bacteriostatic water. Add the water slowly down the vial wall, swirl (don't shake), and let it fully dissolve. Reconstituted peptide is refrigerated and used within its stability window; unmixed powder keeps far longer when stored cold and dark. Always confirm exact dosing math against your own vial and concentration.
Onset & Clearance
Because of its ~33 hours half-life, Melanotan II reaches steady levels after a few consistent doses and clears the system within roughly four to five half-lives once you stop. Track how you respond over a defined block rather than judging any single dose, and give the compound enough consistent days before deciding whether it's working. This is educational information, not medical advice — review your protocol with a clinician.
Physicochemical and PK profile
- Molecular Formula
- C50H69N15O9
- Molecular Weight
- 1024.18 g/mol
- CAS Number
- 121062-08-6
- Half-Life
- Approximately 1 hour
- Sequence
- Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH2
- Solubility
- Soluble in water
- Storage
- Store lyophilized at -20°C protected from light.
References
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- Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. · Wessells H, Levine N, Hadley ME et al. · 2000
- Evaluation of melanotan-II, a superpotent cyclic melanotropic ... · Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME · 1996
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- [PDF] Edward Manookian Docket No. FDA-2015-N-4169 Page 2 · 2015
- Fan W, et al. Role of melanocortinergic neurons in feeding and the agouti obesity syndrome. Nature. 1997;385(6612):165-8. · Holsboer F · 2000
- Melanotan II User Experience: A Qualitative Study of Online Discussion Forums. · Gilhooley E, Daly S, McKenna D · 2021
- Melanotan II: a possible cause of renal infarction - PubMed · Peters B, Hadimeri H, Wahlberg R, Afghahi H · 2020
- Brennan R, et al. Melanotan II: a review of the evidence for efficacy and safety. Dermatology Online Journal. 2019. · Yarosh DB · 2019