PT-141 (Bremelanotide) + AOD-9604 Stack: Safety and Monitoring Guide

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The two halves of this stack are not equivalent

Bremelanotide is a prescription drug approved by FDA as Vyleesi on June 21, 2019, for premenopausal women with acquired, generalized hypoactive sexual desire disorder [2][7]. It is a 1.75 mg subcutaneous injection from a prefilled autoinjector, given in the abdomen or thigh as needed at least 45 minutes before anticipated sexual activity, no more than once in 24 hours and no more than 8 doses a month; the label says to stop after 8 weeks if symptoms have not improved [2]. The label states it is not indicated for HSDD in postmenopausal women or in men, and not to enhance sexual performance [2]. Vyleesi has no boxed warning and no REMS [2][7].

PT-141 sold as a compounded or research-use peptide is not Vyleesi and is not an FDA-approved drug; compounded drugs are not reviewed by FDA for safety, effectiveness or quality before marketing [8][2].

AOD-9604 is a modified 16-amino-acid fragment of human growth hormone: hGH residues 177 to 191 with an extra tyrosine at the front, which is why it also circulates under the name hGH fragment 176-191 [9]. It is not an FDA-approved drug. An Australian company developed it as an obesity candidate, phase IIa trials were underway by February 2002, and the obesity program was later dropped [4][1].

Blood pressure: the labeled monitoring point

Every Vyleesi dose transiently raises blood pressure and lowers heart rate [2]. In clinical studies the maximal increases were 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours after the dose, with a heart rate reduction of up to 5 beats per minute; values usually returned to baseline within 12 hours, and repeat daily dosing 24 hours apart for up to 16 days produced no additive effect [2]. Those 6 and 3 mmHg figures are maximal, not average. In an open-label ambulatory study of 127 premenopausal women dosed once daily for 8 days, mean daytime blood pressure rose 1.9 mmHg systolic (95% CI 1.0 to 2.7) and 1.7 mmHg diastolic (95% CI 0.9 to 2.4), with a mean heart rate decrease of 0.5 beats per minute [2].

The Vyleesi label says cardiovascular risk should be considered and blood pressure should be well controlled before starting treatment and again periodically during treatment [2]. Vyleesi is contraindicated in uncontrolled hypertension or known cardiovascular disease and is not recommended for people at high risk of cardiovascular disease [2].

There is no approved AOD-9604 product, so no label sets any monitoring for it [4][1]. The blood pressure numbers above describe bremelanotide alone, at its approved dose, without AOD-9604.

Nausea, pigmentation and the rest of the labeled profile

Nausea is the most common labeled reaction: 40% on Vyleesi versus 1.3% on placebo in the phase 3 trials, with 13% needing anti-nausea medicine and 8% stopping the trials because of it [2]. It was highest after the first dose (21% of patients) and fell to about 3% with later doses [2]. Pre-treating with oral ondansetron 30 minutes before a dose did not reduce nausea in a phase 4 single-dose study of 228 healthy women and is not recommended [2].

Focal hyperpigmentation (darkening of skin, gums or breasts, including the face) was reported by 1% of patients given up to 8 doses a month versus none on placebo [2]. In another study, 38% of patients developed it after daily dosing for 8 days, and an additional 14% after 8 more consecutive days [2]. Risk is higher in darker skin and with daily dosing, resolution was not confirmed in all patients, and the label says to consider discontinuing if it develops [2]. The label also notes that more frequent dosing increases the risk of focal hyperpigmentation and lengthens the time each month when blood pressure is raised [2].

Other labeled reactions from the pooled phase 3 trials, Vyleesi versus placebo: flushing 20.3% versus 0.3%, injection site reactions 13.2% versus 8.4%, headache 11.3% versus 1.9%, vomiting 4.8% versus 0.2% [2]. Serious adverse reactions were reported in 1.1% versus 0.5%, and 18% versus 2% stopped treatment because of adverse reactions [2]. One case of acute hepatitis occurred in the open-label extension after 10 doses over a year, with transaminases above 40 times normal and no other cause identified [2]. No dose adjustment is recommended for mild to moderate renal impairment; the label advises caution in severe impairment (eGFR <30 mL/min/1.73 m2), where exposure doubles [2].

What is known about AOD-9604 safety

FDA states it has identified serious adverse events that may be associated with AOD-9604, though causality is not clear, and gives no details; its listed concerns include immunogenicity risk from peptide impurities for certain routes of administration and limited safety information [3]. A 2026 review of unapproved performance peptides concludes that rigorous human safety data are scarce and that there is potential for serious harm [10], and another 2026 review notes the uncertainty around product composition and dose in unregulated supply chains [1].

What human data exist for AOD-9604

The main human obesity study described in a 2026 review was a 24-week trial of an oral AOD9604 candidate with 534 enrolled and 502 randomized; it failed to show a significant benefit on the primary weight-loss endpoint [1]. That conclusion rests on sponsor-reported phase 2 results rather than a peer-reviewed randomized paper, and the review notes there are no robust human data for visceral fat reduction or other metabolic benefit [1].

The animal work is more detailed. In obese Zucker rats, oral AOD9604 at 500 micrograms/kg/day for 19 days cut body-weight gain to 15.8 g versus 35.6 g in controls, with greater fat-tissue lipolytic activity and no worsening of insulin sensitivity [11]. In obese mice, 14 days of treatment reduced body weight and fat, and the long-term effect was not seen in mice lacking the beta-3 adrenergic receptor, although the authors concluded the lipolytic action is not mediated directly through that receptor [12]. In vitro, AOD9604 did not compete for the growth hormone receptor or drive cell proliferation, unlike growth hormone [13].

Other labeled interactions of Vyleesi

Vyleesi may slow gastric emptying and reduce absorption of oral medicines; the label says to avoid it with oral drugs that depend on threshold blood concentrations, such as antibiotics, and to consider skipping it when a quick effect from an oral medicine such as indomethacin is wanted [2]. In clinical pharmacology studies only naltrexone and indomethacin were meaningfully affected [2]. The label says to avoid using Vyleesi with oral naltrexone-containing products intended to treat alcohol or opioid addiction, because it may significantly decrease naltrexone exposure and treatment failure is a severe consequence [2]. Alcohol at 0.6 g/kg did not change bremelanotide blood levels in a crossover study of 24 healthy volunteers, and flushing and headache rates with the combination were similar to the higher of the two single-agent rates; that study used a 20 mg intranasal dose, about 2.5-fold the Cmax of Vyleesi [2].

Sport and regulatory status

AOD-9604 is named in WADA's S2.2.3 class for growth hormone fragments and is prohibited at all times, in and out of competition; it appears on the 2026 Prohibited List and on the tracked-changes 2027 List [5][6]. Bremelanotide is not named on WADA's 2026 or 2027 Prohibited List. Because it is approved by FDA, WADA's S0 class for substances with no approval from any governmental health authority does not cover it [5][6].

AOD-9604 sits in the 'nominated but withdrawn' table on FDA's page of bulk substances that may raise significant safety risks when compounded; removal from the higher-risk category was not a finding that it is safe [3]. It appears in none of the three categories on FDA's list for state-licensed pharmacies and physicians, or on the outsourcing-facility list [15][16][18]. It is not one of the six peptides named in HHS's October 2026 draft enforcement-discretion policy [17][8]. Bremelanotide appears on none of those lists either, and the approved product is a prescription medicine [3][2].

FDA's GRAS Notice Inventory contains no AOD-9604 notice, so there is no FDA 'no questions' letter for it. GRAS is also a food-ingredient concept and would not make an injectable product lawful as a drug [14].

Bottom line

Bremelanotide has a label, a defined dose, and labeled safety points: cardiovascular risk and blood pressure before and during treatment, plus nausea and focal hyperpigmentation [2]. AOD-9604 has no approved dose, human evidence is limited, and FDA reports possible serious adverse events with causality unclear [3][1].