Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of Melanotan II and PT-141 — mechanism, side effects, legal status, and pricing.
Melanotan II (MT-II) is a cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) — Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 — developed at the University of Arizona in the 1980s by Hruby, Hadley, and colleagues as a candidate photoprotection / sunless-tanning agent. It has never been approved by the FDA or any other regulator for any indication; clinical development was abandoned and it is sold only via grey-market research-chemical channels. Genuine safety signals have been reported, including darkening of existing moles, eruptive atypical nevi, and case reports of new primary melanoma in young tanning-seeking users.
PT-141 (bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist derived from melanotan II. It is FDA-approved as Vyleesi (2019) for hypoactive sexual desire disorder (HSDD) in premenopausal women only. It acts centrally through the melanocortin system rather than on peripheral vasculature.
Melanotan II
PT-141
Category
Legal Status
Mechanism
Half-life
Side Effects
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
Melanotan II
PT-141
COA corpus from Disclosed Labs — independently tested batches only.
Melanotan II
60
COAs
99.7%
Avg purity
12
Labs
PT-141
83
COAs
99.7%
Avg purity
14
Labs
Melanotan II was developed by Hruby, Hadley, and colleagues at the University of Arizona in the 1980s. The seminal Phase I clinical study is Dorr et al. (Life Sciences, 1996; PMID 8637402), a pilot trial in three healthy male volunteers that documented dose-dependent pigmentation together with nausea, a 'stretching and yawning complex,' and spontaneous penile erections — the MC4R sexual-arousal signal that later motivated the development of bremelanotide (PT-141/Vyleesi). MT-II itself was never advanced to Phase III and has never received regulatory approval in any jurisdiction. As unregulated consumer use expanded through the 2000s, dermatology literature accumulated safety signals: Langan et al. (BMJ 2009, PMID 19174439) reported changes in moles among young users of unlicensed 'sun tan jab' preparations; Cardones & Grichnik (Arch Dermatol 2009, PMID 19380666) described alpha-MSH-induced eruptive atypical nevi in a patient with dysplastic nevi and prior melanoma who used MT-II; Evans-Brown et al. (BMJ 2009, PMID 19224885) documented widespread unregulated population use. Further case reports describe new primary cutaneous melanoma in young MT-II users and rare rhabdomyolysis. Regulators (FDA, UK MHRA, Australian TGA) have explicitly warned against use. Note: the Barnetson et al. 2006 photoprotection study (J Invest Dermatol, PMID 16763547) evaluated the related linear analog [Nle4-D-Phe7]-alpha-MSH (afamelanotide / Melanotan-I), not MT-II. Category 2 classification reflects documented safety concerns from non-selective melanocortin activation combined with oncologic signals.
Key references
Bremelanotide received FDA approval in June 2019 (NDA 210557) based on the two Phase III RECONNECT trials reported by Kingsberg, Simon, Clayton, Portman et al. in Obstet Gynecol 2019 (PMID 31599840). Pooled 24-week data showed statistically significant increases in the Female Sexual Function Index desire domain and decreases in the Female Sexual Distress Scale compared with placebo, with long-term 52-week open-label safety reported in the companion paper (PMID 31599847). Earlier clinical programs in men with erectile dysfunction — including intranasal bremelanotide and the subcutaneous sildenafil-salvage study by Safarinejad & Hosseini (J Urol 2008, PMID 18206919) — showed modest efficacy but did not lead to approval in men. Safety monitoring shows transient SBP elevation (~6 mmHg) with reflex bradycardia resolving within ~12 hours; nausea (~40%) is the most common adverse event and typically diminishes with subsequent doses. Focal hyperpigmentation has been reported with repeated use, consistent with MC1R activity.
Melanotan II (Cosmetic) and PT-141 (Hormone) are in different categories and target different biological pathways. This is a common pattern in multi-compound research protocols. Researchers should monitor the biomarkers from both profiles and watch for interactions listed in each compound’s contraindications. Consult a licensed healthcare provider before combining any research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Contraindications
Lab Testing
Disclosed Labs