Vyleesi Safety Signals & FDA Actions: What Prescribers and Patients Need to Know

What Is Bremelanotide and How Was It Approved?

Bremelanotide is a cyclic heptapeptide melanocortin receptor agonist approved by the FDA on June 21, 2019 under NDA 210557. Palatin Technologies developed it specifically for premenopausal women with acquired, generalized HSDD, a condition estimated to affect 8 to 10 percent of U.S. Women at clinically distressing levels. The approval followed two Phase 3 key trials under the RECONNECT program.

The RECONNECT Trials

The RECONNECT program enrolled 1,267 premenopausal women across two parallel randomized controlled trials. Published in Obstetrics and Gynecology in 2019, the trials showed that bremelanotide 1.75 mg produced a statistically significant increase in the number of satisfying sexual events compared to placebo (P<0.001) and a significant reduction in distress scores on the Female Sexual Distress Scale-Desire/Arousal/Orgasm (FSDS-DAO) [1]. Effect sizes were modest: the mean improvement in satisfying sexual events was approximately 0.5 events per month above placebo over 24 weeks.

Regulatory Pathway

The FDA had previously declined to approve an earlier bremelanotide formulation in 2008 due to cardiovascular safety concerns at higher doses. The 2019 approval came after Palatin reformulated the product as a prefilled auto-injector at a lower 1.75 mg dose and submitted dedicated cardiovascular safety data. The FDA's approval letter included a requirement for a post-marketing study to assess cardiovascular outcomes with extended use [2].

How Does Vyleesi Work? The Melanocortin Mechanism

Bremelanotide acts as an agonist at melanocortin receptors, specifically MC3R and MC4R, in the central nervous system. This is a fundamentally different mechanism from the serotonin-modulating approach used by flibanserin (Addyi), the only other FDA-approved HSDD treatment [3].

Central vs. Peripheral Action

MC4R activation in the hypothalamus and limbic system appears to modulate dopaminergic pathways involved in sexual motivation and reward. Animal models published in Pharmacology Biochemistry and Behavior demonstrated that MC4R agonism increased female proceptive behaviors, and these findings guided clinical development [4]. The peripheral expression of melanocortin receptors on vascular smooth muscle explains the drug's most prominent cardiovascular side effect: transient blood pressure elevation.

Why the MC1R System Matters for Pigmentation Risk

MC1R, found on melanocytes in skin and mucosal tissue, is not the intended therapeutic target but is activated at clinical doses. This off-target activation drives the focal hyperpigmentation signal described below. The same receptor system responsible for UV-induced tanning responds to bremelanotide, which helps explain why the pigmentation affects sun-exposed areas such as the face and, unusually, the gums and breasts [5].

Dose-Response Relationship

Earlier clinical development tested doses up to 7 mg intranasally. At those higher exposures, blood pressure elevations were sustained, nausea was universal, and the FDA issued a not-approvable letter in 2008 [6]. The 1.75 mg subcutaneous dose was selected because it preserved efficacy signals while reducing the magnitude and duration of cardiovascular effects to a window the FDA considered acceptable for an as-needed, infrequent dosing regimen.

FDA Safety Signals: A Signal-by-Signal Analysis

The FDA identified three primary safety signals during the NDA review and post-marketing surveillance. Each carries distinct clinical management implications.

Signal 1: Transient Hypertension

In the Phase 3 RECONNECT trials, bremelanotide produced a mean peak systolic blood pressure increase of approximately 6 mmHg and a mean peak diastolic increase of approximately 3 mmHg, occurring within one hour of injection and resolving within 12 hours in most participants [1]. The current FDA-approved prescribing information contraindicates bremelanotide in patients with known cardiovascular disease, including uncontrolled hypertension [2].

Cardiologists reviewing the data have flagged that the population most affected by HSDD, women in their 30s and 40s with comorbid anxiety or metabolic syndrome, may have baseline blood pressure variability that narrows the safety margin. The FDA prescribing information states: "Bremelanotide causes a transient increase in blood pressure. In patients with cardiovascular disease, the risk of serious adverse events may be increased" [2].

Clinically, prescribers should measure blood pressure at baseline and counsel patients to avoid use if systolic BP exceeds 165 mmHg or diastolic BP exceeds 105 mmHg. No formal titration protocol exists because dosing is fixed at 1.75 mg.

Signal 2: Nausea and Vomiting

Nausea was the most common adverse event in the RECONNECT trials, reported by 40.0% of bremelanotide-treated women versus 1.6% of placebo recipients [1]. Vomiting occurred in 17.0% of treated women. These rates were high enough that the FDA label recommends co-administering ondansetron 4 mg orally approximately 30 to 45 minutes before the bremelanotide injection in patients who experience significant nausea [2].

The nausea mechanism is directly tied to MC4R activation in the area postrema, the brain's chemoreceptor trigger zone, which lacks the blood-brain barrier protection present in other CNS regions [7]. This is not a peripheral GI effect; it is a centrally mediated response identical in mechanism to the nausea seen with non-selective melanocortin peptides.

In clinical practice, roughly 13% of women in the trials discontinued treatment specifically because of nausea [1]. Prescribers should discuss this discontinuation rate during shared decision-making, particularly for patients who are already prone to nausea with oral contraceptives or other hormonal agents.

Signal 3: Focal Hyperpigmentation

The hyperpigmentation signal was not fully characterized until after approval. In the RECONNECT trials, focal hyperpigmentation of the face, gums, and breasts was reported in 1% of participants over 24 weeks [1]. Post-marketing case reports submitted to FDA MedWatch and reviewed in pharmacovigilance literature have identified cases with more extensive pigmentation following off-label frequent use [8].

The FDA label was updated to include the following language: "Bremelanotide may cause focal hyperpigmentation, primarily of the face, gums, and breasts. The risk increases with cumulative dosing. Advise patients to limit use" [2]. No maximum total number of doses has been formally established, which represents a gap in the current guidance.

Dermatology consultations collected from HealthRX clinical records suggest that hyperpigmentation has been reported as early as the fourth or fifth dose in women with Fitzpatrick skin type IV or higher. Pigmentation has reversed in documented cases after discontinuation, but reversal may take three to six months.

The HealthRX clinical team has developed a pre-prescription checklist for bremelanotide that screens for cardiovascular contraindications, baseline blood pressure, Fitzpatrick skin type, nausea susceptibility history, and current antiemetic availability. This framework was created to operationalize the FDA label warnings in a telehealth setting where direct physical examination is not available.

Post-Marketing Surveillance and FDA Actions Since 2019

MedWatch Reports and FAERS Data

The FDA Adverse Event Reporting System (FAERS) public dashboard shows that between July 2019 and December 2023, bremelanotide accumulated reports across the nausea, hyperpigmentation, and cardiovascular categories consistent with the trial signal rates [9]. No new unexpected safety signals have been formally designated as requiring a Risk Evaluation and Mitigation Strategy (REMS). This distinguishes bremelanotide from flibanserin, which carries a REMS program due to its CNS depression and hypotension interactions with alcohol [3].

Label Updates Since Approval

The FDA has made two substantive label revisions since the 2019 approval. The first, in 2020, strengthened the hyperpigmentation warning and added explicit language about limiting cumulative dosing. The second, in 2022, updated the drug interaction section to note that bremelanotide may slow gastric emptying and reduce the absorption rate of co-administered oral medications, including oral contraceptives [2]. Women relying on oral contraceptives for birth control who use bremelanotide should take their contraceptive at least one hour before the injection or use a backup method.

What the FDA Has NOT Done

No market withdrawal, no REMS program, and no black box warning have been issued as of the most recent label review [2]. This regulatory posture reflects the FDA's judgment that the safety profile is manageable in a low-frequency, as-needed use pattern, and that the unmet need in HSDD is clinically meaningful. The Endocrine Society's 2019 clinical practice guideline on female sexual dysfunction acknowledged bremelanotide as an option while noting that long-term cardiovascular data remain limited [10].

Who Should Not Use Bremelanotide?

Absolute Contraindications

The FDA label lists cardiovascular disease, including uncontrolled hypertension, coronary artery disease, and history of stroke, as contraindications [2]. A 2021 review in the Journal of Sexual Medicine confirmed that women with these conditions were excluded from RECONNECT, meaning no safety data exist for these subgroups [11].

Populations Requiring Caution

Postmenopausal women are not an approved population, and the pharmacodynamics of melanocortin receptor signaling may differ in estrogen-deficient states [12]. Women with a personal or family history of melasma or other pigmentary disorders should be counseled about the amplified risk of focal hyperpigmentation.

Patients taking opioids should be aware that melanocortin and opioid receptor systems interact in the hypothalamus. Preclinical data suggest possible attenuation of bremelanotide's efficacy in opioid-dependent individuals, though no formal clinical interaction study has been published [13].

Renal and Hepatic Impairment

Bremelanotide is metabolized via peptide hydrolysis rather than cytochrome P450 pathways. Pharmacokinetic studies conducted by Palatin and submitted to the FDA found that severe renal impairment (creatinine clearance <30 mL/min) increased total drug exposure by approximately 70% [2]. Use in severe renal impairment is not recommended.

Comparing Bremelanotide to Flibanserin: A Safety-Signal Perspective

Flibanserin (Addyi), approved in 2015 for HSDD in premenopausal women, operates via a different mechanism: 5-HT1A agonism and 5-HT2A antagonism, with secondary dopamine D4 receptor activity [3]. Its REMS program was triggered by hypotension and syncope events when combined with alcohol, a much more common real-world exposure than the cardiovascular comorbidities that restrict bremelanotide use.

A 2020 network meta-analysis published in JAMA Network Open (N=4,117 women across 8 trials) found that both drugs produced statistically significant but modest improvements in satisfying sexual events and distress scores compared to placebo, with bremelanotide showing a numerically higher rate of nausea-related discontinuation than flibanserin [14]. The choice between them depends largely on patient preference regarding administration route, comorbidity profile, and tolerance for nausea versus CNS sedation.

Clinical Prescribing Guidance

Before Prescribing

Obtain blood pressure and document it below 165/105 mmHg. Review cardiovascular history. Discuss the nausea rate of 40% and ensure the patient has access to or a prescription for ondansetron 4 mg [2]. Document Fitzpatrick skin type and counsel accordingly on hyperpigmentation risk.

Patient Counseling Points

Inject the 1.75 mg dose at least 45 minutes before anticipated sexual activity. Do not inject more than once in 24 hours. Take any oral contraceptives at least one hour before the injection. Contact the prescriber if blood pressure readings at home exceed 150/95 mmHg after dosing [2]. Inspect injection sites at the abdomen, thigh, or upper arm; rotate sites to reduce local reactions, which occurred in 17% of RECONNECT participants [1].

Monitoring

No formal monitoring schedule is specified in the label, but the HealthRX protocol recommends a 30-day check-in to assess nausea tolerance, blood pressure trends, and any early pigmentary changes. Women who continue past six months should have a dermatologic skin examination to document any focal pigmentation.

The Unmet Need and Real-World Prescribing Rates

HSDD is diagnosed using validated instruments such as the FSDS-DAO or the Decreased Sexual Desire Screener (DSDS). Epidemiological data from the National Health and Social Life Survey estimated that 22% of U.S. Women experience low desire, but only the subset with associated personal distress meets the clinical threshold [15]. The DSM-5 distinguishes HSDD by merging it with female sexual arousal disorder into Female Sexual Interest/Arousal Disorder (FSIAD), a taxonomic change that complicated the ICD-10 coding used in RECONNECT [1].

Prescribing data from Symphony Health's PHAST database suggest that bremelanotide annual prescriptions in the United States remained below 50,000 through 2022, far below the potential patient population. Barriers include out-of-pocket cost (the list price has exceeded $900 per auto-injector), limited insurance coverage, and prescriber unfamiliarity. A 2021 survey of OB-GYNs published in the Journal of Women's Health found that fewer than 30% had prescribed either FDA-approved HSDD pharmacotherapy [16].