# Setmelanotide (Imcivree): Evidence, Mechanism & Legal Status

> A clinical monograph on setmelanotide (Imcivree) — the MC4R-agonist octapeptide approved for rare genetic and hypothalamic obesity. Grade A human evidence in narrow indications, not a general weight-loss drug.

*Published 2026-06-30 · Updated 2026-07-01 · By Marcus Feld, PharmD, BCPS*

The short answer
Setmelanotide (Imcivree) is a synthetic MC4R-agonist octapeptide with **Grade A human evidence** — completed phase 3 trials, including randomized placebo-controlled designs — but **only in a narrow set of patients** whose hypothalamic satiety pathway is broken by upstream genetic defects or injury. It is fully FDA-approved, but it is **not** a general weight-loss drug and has never been studied in common obesity.[1](https://peptidevox.com/#r1)[16](https://peptidevox.com/#r16)

Setmelanotide (Imcivree, formerly RM-493) is a synthetic disulfide-cyclized octapeptide that agonizes the melanocortin-4 receptor (MC4R), re-activating the hypothalamic leptin-melanocortin satiety pathway when it is broken by upstream genetic defects.[13](https://peptidevox.com/#r13) It is the first precision therapy to target the root cause of specific rare genetic obesities rather than treating obesity generically. This monograph separates what is proven from what is hyped.

*This article is informational and editorial content for research and educational purposes only. It is not medical advice, not a protocol to follow, and not a sourcing guide. Setmelanotide is an FDA-approved prescription drug used under specialist supervision after genetic or diagnostic confirmation. Dosing figures are reported strictly as seen in the published literature for completeness — not as recommendations. Consult a licensed clinician before any health decision.*

## What is setmelanotide and how does it work?

Setmelanotide is a synthetic disulfide-cyclized octapeptide (8 amino acids) that retains the specificity of alpha-melanocyte-stimulating hormone (alpha-MSH), the endogenous POMC-derived MC4R ligand, while being more potent and longer-lived than native alpha-MSH.[13](https://peptidevox.com/#r13) It binds human MC4R with high affinity (Ki approximately 2.1 nM) and activates it potently (EC50 approximately 0.27 nM), with roughly 20-fold lower activity at MC3R and MC1R, and it can cross into the hypothalamus to act on central MC4R.[13](https://peptidevox.com/#r13)

The pathway is the heart of the mechanism. Leptin signals via the leptin receptor (LEPR) on hypothalamic POMC neurons, driving POMC processing by the protease PCSK1 into alpha-MSH, which activates MC4R to increase satiety and energy expenditure.[14](https://peptidevox.com/#r14) Loss-of-function variants in *POMC*, *PCSK1* or *LEPR* — or ciliopathy-driven pathway impairment in Bardet-Biedl syndrome, or hypothalamic injury in acquired hypothalamic obesity — reduce alpha-MSH signaling at MC4R, producing insatiable hunger (hyperphagia) and early-onset severe obesity.[1](https://peptidevox.com/#r1) Setmelanotide restores the impaired MC4R-pathway activity downstream of these defects.[14](https://peptidevox.com/#r14) Administered subcutaneously, it has an effective elimination half-life of about 11 hours, supporting once-daily dosing, and roughly 39 percent of a dose is excreted unchanged in urine over 24 hours.[10](https://peptidevox.com/#r10)

## What is the evidence by indication?

Unlike many marketed peptides, setmelanotide carries completed phase 3 human trials. Every indication below is human evidence, graded A — but the grade applies only to these specific, confirmed diagnoses.

  Setmelanotide evidence by indication

    IndicationBest evidenceGrade

    POMC / PCSK1 deficiency obesityPhase 3 open-label + placebo-withdrawal; 8 of 10 (80%) achieved ≥10% weight lossA (human)
    LEPR deficiency obesityPhase 3 open-label + placebo-withdrawal; 5 of 11 (45%) achieved ≥10% weight lossA (human)
    Bardet-Biedl syndrome (BBS)Randomized double-blind placebo-controlled phase 3; ~32% lost ≥10% body weight at 52 weeksA (human RCT)
    Acquired hypothalamic obesityTRANSCEND randomized placebo-controlled phase 3; −15.8% BMI vs +2.6% placeboA (human RCT)
    Common (polygenic) obesityNot studied, not approved; mechanism-specific benefit does not applyNo qualifying evidence

In the pivotal phase 3 POMC-deficiency trial ([NCT02896192](https://clinicaltrials.gov/study/NCT02896192)), patients aged 6 and older received open-label setmelanotide for 12 weeks, and responders entered an 8-week double-blind placebo-controlled withdrawal phase; 8 of 10 (80 percent) achieved at least 10 percent weight loss at about one year, with a mean change in the worst-hunger score of negative 27.1 percent (p=0.0005).[2](https://peptidevox.com/#r2)[8](https://peptidevox.com/#r8) In the parallel LEPR trial, 5 of 11 (45 percent) achieved at least 10 percent weight loss, with hunger scores falling 43.7 percent (pProven vs hyped
Proven: clinically meaningful weight loss and large hunger reductions in genetically or etiologically confirmed indications. Hyped: any use as a general weight-loss peptide — setmelanotide has never been studied or approved for common polygenic obesity, which is exactly what separates it from broad agents like GLP-1 receptor agonists.[1](https://peptidevox.com/#r1)

## What doses appear in the literature?

Reported strictly as information, not a protocol. The route is subcutaneous injection once daily into the abdomen, thigh or upper arm, supplied as a multidose vial.[10](https://peptidevox.com/#r10) The reported titration starts at 0.5 mg (0.05 mL) once daily for about two weeks; if tolerated, it increases to 1 mg, then to a maintenance dose of 1.5 mg (0.15 mL) once daily, with the label permitting up to 3.0 mg depending on age, indication and tolerability.[10](https://peptidevox.com/#r10) The label advises evaluating weight or BMI response at about 12 to 16 weeks and discontinuing if reduction is below 5 percent.[13](https://peptidevox.com/#r13) No change is needed for mild or moderate renal impairment, but the drug is not recommended in end-stage renal disease.[10](https://peptidevox.com/#r10) Because this is the approved branded product, the only legitimate supply is a dispensed prescription — not research-grade vials.

## How safe is setmelanotide?

The most common adverse reactions (incidence at or above 20 percent) are skin hyperpigmentation, injection-site reactions, nausea, headache, diarrhea, abdominal pain, vomiting, depression and spontaneous penile erection.[10](https://peptidevox.com/#r10)[21](https://peptidevox.com/#r21) Because melanocytes express MC1R, agonism drives melanin accumulation independent of UV, causing generalized skin darkening, darkening of pre-existing moles and new melanocytic nevi — reversible on discontinuation, but the label mandates skin exams before and during treatment, with chronic melanocyte stimulation a theoretical melanoma concern.[13](https://peptidevox.com/#r13) Spontaneous penile erections occurred in 24 percent of males aged 6 and older, attributed to MC4R modulation of central sexual processing, with patients advised to seek emergency care for erections lasting more than four hours.[10](https://peptidevox.com/#r10) Depression, depressed mood and suicidal ideation have occurred and require monitoring; serious hypersensitivity including anaphylaxis has been reported.[10](https://peptidevox.com/#r10) Weight loss is not advised in pregnancy, and the multidose formulation contains benzyl alcohol, so use is generally avoided in pregnancy and breastfeeding absent compelling benefit.[13](https://peptidevox.com/#r13)

## What is the FDA and WADA status in 2026?

Setmelanotide is a fully FDA-approved prescription drug, not a research chemical. Imcivree (NDA 213793) received initial approval in November 2020 for chronic weight management in patients aged 6 and older with POMC, PCSK1 or LEPR deficiency confirmed by an FDA-approved genetic test.[15](https://peptidevox.com/#r15)[11](https://peptidevox.com/#r11) The label then expanded to Bardet-Biedl syndrome (June 2022), to children aged 2 and older for BBS and the genetic deficiencies (December 2024), and to acquired hypothalamic obesity for ages 4 and older on March 19, 2026 after Priority Review.[17](https://peptidevox.com/#r17)[16](https://peptidevox.com/#r16)[19](https://peptidevox.com/#r19) It is also authorized in the EU and the UK for genetically confirmed BBS and POMC/PCSK1/LEPR deficiency.[4](https://peptidevox.com/#r4) Because it is a commercially available branded drug, it is dispensed as the approved product; any non-pharmacy research setmelanotide is unapproved and outside legitimate channels.

For athletes the picture is more nuanced than for a banned research peptide. Setmelanotide is not specifically named on the 2026 WADA Prohibited List, but as a peptide-hormone mimetic acting on the melanocortin system it could plausibly be argued under category S2.[22](https://peptidevox.com/#r22)[23](https://peptidevox.com/#r23) There is no legitimate performance indication for it, so its only relevance to athletes is as an anti-doping consideration. Any tested athlete should verify current status via GlobalDRO and seek a Therapeutic Use Exemption where medically indicated.[22](https://peptidevox.com/#r22)

**Bottom line.** Setmelanotide is a genuine precision-medicine success — Grade A human evidence supports clinically meaningful weight loss and large reductions in hyperphagia in a narrowly defined set of patients whose MC4R satiety pathway is broken by upstream genetic defects or hypothalamic injury. What is proven is benefit in these confirmed indications; what is unsupported is any use as a general weight-loss peptide. Key uncertainties include small sample sizes inherent to ultra-rare diseases, the theoretical long-term melanocytic-tumor risk from chronic melanocyte stimulation, and unknowns in elderly, hepatic and pregnant populations. Regulatory facts here are current as of June 2026 and should be re-verified for any later changes.

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Source: https://peptidevox.com/peptide-encyclopedia/mt-1-vitiligo
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