Peptide Schedule
Setmelanotide8 residues (approx.)CEHFRWCKEach bubble = one amino acid. Size = residue mass. Color = chemical class.Uses closest standard amino acids for non-standard residues.Setmelanotide
Benefits
About Setmelanotide
Setmelanotide is the first and only FDA-approved treatment targeting the melanocortin-4 receptor (MC4R) pathway for patients with rare genetic obesity disorders. Sold under the brand name IMCIVREE, it was approved in November 2020 for adults and children aged 6+ with obesity caused by POMC, PCSK1, or LEPR deficiency confirmed by genetic testing — and later expanded to include Bardet-Biedl syndrome in 2022. Unlike GLP-1 agonists that work through gut hormones and appetite signaling, setmelanotide acts directly on MC4R in the hypothalamus to restore the satiety signaling that these patients are missing due to their genetic mutations. In patients with POMC deficiency, the body cannot produce alpha-MSH, the natural ligand for MC4R. Setmelanotide steps in as a synthetic replacement, reactivating the downstream hunger-off switch. The clinical results in the right patient population are striking. In phase 3 trials, 80% of POMC-deficient patients achieved at least 10% body weight loss at one year, with a mean reduction of 25.6%. LEPR-deficient patients saw a mean 12.5% weight loss. These are patients who previously had zero effective treatment options and experienced constant, unrelenting hunger from birth. Setmelanotide is an 8-amino-acid cyclic peptide — structurally related to alpha-MSH but engineered for selectivity at MC4R over MC1R, though it still activates MC1R enough to cause skin darkening (hyperpigmentation) in most patients. It comes as a 10mg/mL multi-dose vial for daily subcutaneous injection. The 11-hour half-life means steady-state is reached within about 2 days of daily dosing.
Who Should Consider Setmelanotide
- Patients aged 6+ with genetically confirmed POMC deficiency obesity
- Patients with PCSK1 deficiency obesity
- Patients with LEPR deficiency obesity
- Patients with Bardet-Biedl syndrome (BBS)
- Individuals who have failed all conventional obesity treatments due to monogenic causes
How Setmelanotide Works
Setmelanotide is a cyclic 8-amino-acid peptide analog of alpha-melanocyte stimulating hormone (alpha-MSH) that acts as a selective agonist at the melanocortin-4 receptor (MC4R). In normal physiology, leptin activates POMC neurons in the arcuate nucleus of the hypothalamus, which produce alpha-MSH. Alpha-MSH then binds MC4R on downstream neurons in the paraventricular nucleus to suppress appetite and increase energy expenditure. In patients with POMC, PCSK1, or LEPR deficiency, this signaling cascade is broken — the brain never receives the 'stop eating' signal. Setmelanotide bypasses these upstream defects entirely by directly activating MC4R, restoring satiety signaling regardless of whether the patient can produce leptin responses, POMC, or processed alpha-MSH. It also activates MC1R (responsible for skin pigmentation) and MC3R to a lesser degree, which accounts for the hyperpigmentation seen in most treated patients. The drug's disulfide-bridged cyclic structure gives it proteolytic stability and a plasma half-life of approximately 11 hours — long enough for once-daily dosing. Protein binding is 79.1%, and it distributes into a volume of about 49-75 L.
What to Expect
Dose titration from 1-2mg to target dose. Appetite suppression begins within the first week. Injection site reactions and early hyperpigmentation may appear.
Noticeable reduction in hunger and food-seeking behavior. Patients and caregivers often report the first time the patient has ever felt full.
Measurable weight loss begins. Skin darkening becomes more apparent. Hunger scores drop 27-44% on average.
Steady weight loss continues — mean 25.6% in POMC patients, 12.5% in LEPR patients at 52 weeks. Quality of life improvements reported as early as week 5.
Dosing Protocol
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 1mg | Daily |
| Moderate | 2mg | Daily |
| Aggressive | 3mg | Daily |
Note: FDA-approved as IMCIVREE for genetic obesity only (POMC, PCSK1, LEPR, BBS deficiency). Requires confirmed genetic testing before prescribing. Titrate from 1mg daily. Monitor for skin hyperpigmentation.
How to Inject Setmelanotide
Inject subcutaneously once daily at the start of the day. Abdomen, thigh, or upper arm are acceptable sites — rotate to avoid injection site reactions. Begin at 1mg daily for pediatric patients under 12, 2mg for those 12 and older. If inadequate response after 2 weeks, increase to 2mg or 3mg respectively. Maximum dose is 3mg/day. No reconstitution needed — IMCIVREE is supplied as a ready-to-use 10mg/mL solution.
Cycling Protocol
Designed for continuous daily use in patients with confirmed genetic obesity. Discontinuation leads to return of hyperphagia and weight regain. Treatment is lifelong in responders.
Pharmacokinetics
Source: IMCIVREE FDA Prescribing Information, Section 12.3 Pharmacokinetics
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Side Effects
Skin hyperpigmentation is the most common effect, reported in about 61% of patients — it results from MC1R activation in melanocytes and is generally cosmetic rather than harmful. Injection site reactions (erythema, pruritus) affect roughly 48%. Nausea, diarrhea, and abdominal pain occur at moderate rates. Spontaneous penile erections have been reported in male patients due to MC4R's role in sexual function. Depression and suicidal ideation are listed as warnings in the prescribing label; patients should be monitored. Skin and eye exams are recommended before starting therapy due to rare reports of darkening of pre-existing nevi.
Contraindications
- Known hypersensitivity to setmelanotide or any excipients
- Obesity not caused by POMC, PCSK1, LEPR deficiency, or BBS (will not work in common obesity)
- Pregnancy — discontinue if pregnancy occurs
- Patients with major depressive disorder or active suicidal ideation (monitor closely if initiating)
Drug Interactions
- No formal drug interaction studies have been conducted
- Setmelanotide is cleared by proteolytic catabolism, not CYP enzymes — low risk of metabolic drug interactions
- Caution with drugs that affect melanocortin signaling or cause depression
- Renal impairment increases exposure by 13-96% depending on severity — no dose adjustment per label, but monitor
Storage & Stability
Molecular Profile
Related Peptides
References
- Phase 3 Trials — Setmelanotide in POMC and LEPR Deficiency Obesity (Clement et al.)PubMed 33137293
- Phase 3 Trial — Setmelanotide in Bardet-Biedl Syndrome (Haqq et al.)PubMed 36356613
- Setmelanotide Effect on Obesity in Bardet-Biedl Syndrome (Haqq et al. 2020)PubMed 32627316
- IMCIVREE (Setmelanotide) FDA Prescribing InformationFDA Label