What PT-141 is
PT-141 is a name the published record uses for bremelanotide. The title of a paper published in 2006 calls the peptide it studied "bremelanotide (PT-141), a melanocortin receptor agonist".
Bremelanotide is the drug in Vyleesi, an FDA-approved injection. The Vyleesi label calls bremelanotide acetate "a synthetic, cyclic heptapeptide", and elsewhere describes bremelanotide as a peptide with 7 amino acids. It gives the molecular weight as 1025.2 for the free base, and it calls bremelanotide a melanocortin receptor agonist.
The label doesn't use the name PT-141. It says bremelanotide throughout.
Where it stands with the FDA
The FDA first approved bremelanotide in 2019, as Vyleesi. The label on DailyMed, the National Library of Medicine's collection of drug labels, is from Cosette Pharmaceuticals, Inc. A search of DailyMed for bremelanotide in October 2026 returned one label, and it's the Vyleesi injection.
Vyleesi isn't a vial of powder to mix. The label says it's supplied as a sterile, clear solution in a pre-filled syringe contained in a single-dose autoinjector, and that it's self-administered with that autoinjector pen. The label's instructions say to use 1 autoinjector for a dose and throw it away after the injection. The label has no step for mixing a powder with water, and none for drawing liquid out of a vial.
So this calculator has nothing to do with Vyleesi. It only does the arithmetic for a vial of PT-141 powder, and a vial of powder isn't the product that label covers.
The label counts milligrams two ways. It says each pre-filled syringe contains 1.75 mg of bremelanotide, equivalent to 1.89 mg of bremelanotide acetate, in 0.3 mL of solution. This calculator can't tell which way the milligrams on a vial were counted. It works from the number you type in.
PT-141 isn't on the FDA's list of substances nominated for compounding, updated May 14, 2026, under that name or as bremelanotide.
What the label says
The Vyleesi label says it's "indicated for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD)", which it describes as low sexual desire that causes marked distress or interpersonal difficulty and isn't due to a co-existing medical or psychiatric condition, problems with the relationship, or the effects of a medication or drug substance. It lists two limits. Vyleesi "is not indicated for the treatment of HSDD in postmenopausal women or in men", and it "is not indicated to enhance sexual performance".
The label says "The recommended dosage of VYLEESI is 1.75 mg administered subcutaneously in the abdomen or thigh, as needed, at least 45 minutes before anticipated sexual activity." It says patients "should not administer more than one dose within 24 hours", because doses close together "may increase the risk of additive effects on blood pressure", and that "Administering more than 8 doses per month is not recommended." It also says to discontinue Vyleesi after 8 weeks if the patient doesn't report an improvement in her symptoms.
That dosage is the label's, for the Vyleesi autoinjector and for the patients the label covers. The label gives no dose for bremelanotide powder mixed with water, and this page doesn't either.
The label says Vyleesi "is contraindicated in patients who have uncontrolled hypertension or known cardiovascular disease", and that it "is not recommended for patients at high risk for cardiovascular disease". It says Vyleesi "transiently increases blood pressure and reduces heart rate after each dose", and that in clinical studies blood pressure and heart rate returned to baseline usually within 12 hours post-dose.
On skin darkening, the label says that in its phase 3 placebo-controlled trials focal hyperpigmentation, including of the face, gums and breasts, was reported in 1% of patients who received up to 8 doses per month. In another clinical study, it says, "38% of patients developed focal hyperpigmentation after receiving VYLEESI daily for 8 days", and among patients who continued for 8 more consecutive days, an additional 14% developed new focal pigmentary changes. It says "Patients with dark skin were more likely to develop focal hyperpigmentation", and that resolution "was not confirmed in all patients after discontinuation".
On nausea, the label says it was the most commonly reported adverse reaction in those trials, "reported in 40% of VYLEESI-treated patients, requiring anti-emetic therapy in 13% of VYLEESI-treated patients and leading to premature discontinuation from the trials for 8% of VYLEESI-treated patients". The most common adverse reactions it lists, each in more than 4% of patients, are "nausea, flushing, injection site reactions, headache, and vomiting".
On other medicines, the label says Vyleesi "may slow gastric emptying and thus has the potential to reduce the rate and extent of absorption of concomitantly administered oral medications". It says patients should avoid using Vyleesi with a naltrexone-containing product taken by mouth to treat alcohol and opioid addiction, "due to the severe consequence of naltrexone treatment failure".
The label reports a single case of acute hepatitis in the open-label extension phase of one study, and says "the role of VYLEESI could not definitively be excluded". It says to use Vyleesi with caution in patients with severe renal impairment or severe hepatic impairment.
The label says there have been no reports of overdosage with Vyleesi, and that "Nausea, focal hyperpigmentation and more pronounced blood pressure increases are more likely with higher doses."
The label also says what isn't known. Safety and effectiveness "have not been established in pediatric patients" or in geriatric patients, the duration of efficacy after each dose "is unknown", and the mechanism by which Vyleesi improves HSDD in women "is unknown". Based on findings in animal studies, it says use in pregnant women "may be associated with the potential for fetal harm", and that women should use effective contraception while taking Vyleesi and discontinue it if pregnancy is suspected.
Storing PT-141
The Vyleesi label says to store the autoinjector at or below 25°C (77°F), not to freeze it and to protect it from light. It has no storage instructions for a powder or for a vial mixed with water.
The Vyleesi label has no mixing step, so it doesn't say how long a vial of PT-141 mixed with water keeps. Neither do the other documents this page rests on.
PT-141 dosage calculator questions
How do I turn a PT-141 dose into syringe units?
Divide the dose by the concentration to get millilitres, then multiply by 100. A 5 mg vial mixed with 2 mL is 2.5 mg/mL, so one unit on an insulin syringe holds 25 mcg and ten units hold 250 mcg.
How much bacteriostatic water goes in a 5 mg vial of PT-141?
There's no single right amount. The water only sets the concentration, and the amount of PT-141 in the vial stays the same. With 5 mg, 1 mL makes 5 mg/mL, 2 mL makes 2.5 mg/mL and 3 mL makes 1.667 mg/mL. Choose the amount that puts your dose somewhere between about 10 and 40 units, where it's easiest to read.
Is PT-141 approved by the FDA?
Not as a powder to mix. Bremelanotide, which a published paper also calls PT-141, is the drug in Vyleesi, which the FDA first approved in 2019. Vyleesi is a ready-mixed solution in a single-dose autoinjector. A vial of PT-141 powder isn't that product.
Does this page tell me how much PT-141 to take?
No. The Vyleesi label has a dosage for its own autoinjector, and this page reports it as what the label says and nothing more. The label gives no dose for a powder mixed with water. The dose box starts empty for that reason, and the chart only converts.
Is PT-141 the same thing as bremelanotide?
They're two names for one peptide in the published record. The title of a 2006 paper reads "bremelanotide (PT-141), a melanocortin receptor agonist". That's about the molecule. It doesn't make a vial labeled PT-141 the same product as Vyleesi, the approved autoinjector.
Can I use this calculator for Vyleesi?
No. Vyleesi is a single-dose autoinjector that comes ready-mixed. It isn't mixed with water or drawn into an insulin syringe, so there's nothing to convert.
Is Vyleesi approved for men?
No. The label says Vyleesi "is not indicated for the treatment of HSDD in postmenopausal women or in men". HSDD is hypoactive sexual desire disorder. The label also says Vyleesi "is not indicated to enhance sexual performance".
More peptide calculators by name
The same instrument, set up one peptide at a time. For any other vial, use the peptide reconstitution calculator.