PT-141 Female Dosage: 1.75 mg Label Dose, Timing and Limits

Every figure in this table is taken from the Vyleesi prescribing information on DailyMed (SPL version effective November 2025). Nothing here is extrapolated.

There is no titration ladder. The approved PT-141 female dosage is a single fixed amount, not a starting dose that is stepped up, and the label gives no lower or higher alternative strength.

The label instruction is "at least 45 minutes before anticipated sexual activity". It then adds two caveats that matter for anyone planning around a dose: the duration of effect after each dose is unknown, and the optimal window for taking it has not been fully characterized. Patients may choose their own timing based on how they experience the effect on desire and side effects such as nausea.

The pharmacokinetics in the label explain the 45-minute figure. After a subcutaneous injection, bremelanotide reaches its peak blood level at a median of about 1 hour (range 0.5 to 1 hour), and its mean terminal half-life is about 2.7 hours (range 1.9 to 4.0 hours). Bioavailability is about 100%, and the label found no meaningful difference in exposure between abdomen and thigh injections. For rotating sites, see the peptide injection sites guide.

The two limits are not arbitrary, and the label gives its reasons.

• One dose per 24 hours. The efficacy of consecutive doses within 24 hours has not been established, and doses close together may add to the blood-pressure effect.
• No more than 8 a month. Few patients in the phase 3 programme took more than 8 doses a month, and more frequent dosing raises the risk of focal hyperpigmentation and lengthens the time each month that blood pressure is raised.

The trial protocol actually allowed up to 12 doses a month, but real use was far lower: across the two pivotal trials the median was 10 injections over the 24-week double-blind period, and most patients used it two to three times a month and no more than once a week. The hyperpigmentation data show why daily use is discouraged. At up to 8 doses a month, 1% of patients developed darkened patches (face, gums, breasts). In a separate study where bremelanotide was given daily for 8 days, 38% did, and resolution was not confirmed in every case after stopping. Patients with darker skin were more likely to be affected.

The label's overdose section adds that nausea, hyperpigmentation and larger blood-pressure rises are more likely at higher doses, and that peak blood levels plateau at around 7.5 mg. Taking more than 1.75 mg buys more side effects, not a proportionally larger effect.

Nausea is the side effect that decides whether most people keep using it. In the pooled phase 3 trials, 40% of women on bremelanotide reported nausea against about 1% on placebo. It usually began within an hour of the dose, lasted around two hours, was worst after the first dose and improved for most patients by the second. It led to anti-nausea medication in 13% and to stopping the trial in 8%.

Source: Table 1 of the Vyleesi prescribing information. The label notes most events were mild (31%) or moderate (40%) and transient.

Bremelanotide raises blood pressure and lowers heart rate after every dose. In clinical studies the maximum average rise was 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours after the dose, with heart rate falling by up to 5 beats per minute. Both usually returned to baseline within 12 hours.

• Contraindicated with uncontrolled hypertension or known cardiovascular disease, and not recommended for anyone at high cardiovascular risk.
• Oral naltrexone: bremelanotide may sharply reduce its absorption, so the label says to avoid using it with oral naltrexone products for alcohol or opioid dependence.
• Other oral medicines: it may slow gastric emptying, which can delay or reduce absorption of drugs that need a threshold level, such as antibiotics.
• Pregnancy: the label advises effective contraception while using it and stopping if pregnancy is suspected.
• Kidney or liver impairment: no adjustment for mild to moderate impairment; use with caution in severe impairment because nausea and vomiting may be more frequent.

Bremelanotide and PT-141 are the same molecule by name, but the products are not equivalent. The 1.75 mg figure, the timing and the limits were established for the Vyleesi autoinjector, a fixed-dose, sterile, FDA-approved product. Vials sold online as "PT-141" for research are not approved for human use, and the labelled amount on them is the seller's claim rather than a verified assay.

The PT-141 dosage page covers the compound in more depth, including the melanocortin mechanism and the trial history.

When a powder vial is mixed with bacteriostatic water, the volume to draw depends entirely on how much water was added. The formula on a U-100 insulin syringe is:

units = dose in mg ÷ (vial mg ÷ mL of water) × 100

Example only: a vial labelled 10 mg mixed with 3 mL of water gives 3.33 mg/mL. The label-equivalent 1.75 mg would be 1.75 ÷ 3.33 = 0.525 mL, which is 52.5 units on a U-100 syringe. The table shows how the same 1.75 mg moves with the amount of water. These are arithmetic illustrations, not a recommendation to use a research product.

Run your own numbers in the PT-141 calculator or the general mg to mL to units converter. For mixing technique see the reconstitution guide, and for reading the barrel see the syringe measurement guide. The maths is exact; the uncertainty sits in whether the vial really contains what its label says.

Approval rested on two identical 24-week, randomized, placebo-controlled phase 3 trials (RECONNECT, studies 301 and 302) in 1,247 premenopausal women with HSDD, published by Kingsberg and colleagues in Obstetrics & Gynecology in 2019. Women self-injected 1.75 mg as needed. Compared with placebo, bremelanotide improved the Female Sexual Function Index desire score by 0.35 points in the integrated analysis (on a 1.2 to 6.0 scale) and reduced distress about low desire by 0.33 points (on a 0 to 4 scale). Both differences were statistically significant.

Those effects are modest, and not everyone reads them favourably. A 2024 analysis by Spielmans and Ellefson in the Journal of Sex Research argued that the outcome measures had limited validity evidence in women with HSDD and that effect sizes on several previously unpublished secondary outcomes ranged from nil to small. Both papers are worth reading before deciding whether the nausea trade-off is acceptable.

The earlier phase 2b dose-finding study is the reason 1.75 mg was chosen: a 2019 responder analysis reports that the 1.75 mg dose beat placebo on all seven endpoints examined, and that dose went forward into the phase 3 programme.