How long does PT-141 stay in your system?
PT-141 has a published half-life of approximately 2.7 hours (range 1.9 to 4.0). By the standard pharmacology rule of thumb, a drug is about 97% eliminated after roughly five half-lives, which here works out to about 13.5 hours. Across individuals the published range is 1.9 to 4.0 hours, which puts the same rule anywhere from 9.5 to 20 hours.
Source: Vyleesi label, DailyMed · FDA label · measured: subcutaneous · dataset reviewed September 23, 2026
What is the half-life of PT-141?
The Vyleesi prescribing information gives bremelanotide, the approved form of PT-141, a mean terminal half-life of approximately 2.7 hours after a single subcutaneous dose, with a range of 1.9 to 4.0 hours. Bremelanotide is a cyclic peptide that activates melanocortin receptors in the brain, and it descends from the melanotan II line of research.
The range deserves as much attention as the mean. A spread of 1.9 to 4.0 hours means some people clear bremelanotide roughly twice as fast as others, a reminder that a label mean describes a group, not an individual. On the single-compartment arithmetic, seven half-lives at the mean, about 19 hours, takes a single dose below 1% of its starting level.
How much PT-141 is left after each half-life?
Each half-life removes half of whatever is left, so the percentages are pure arithmetic and the same for any compound; only the clock changes. For PT-141, one half-life is 2.7 hours. The rows below run that forward for a single amount with nothing added.
| Half-lives elapsed | Time elapsed | Remaining | Cleared |
|---|---|---|---|
| 1 | 2.7 hours | 50% | 50% |
| 2 | 5.4 hours | 25% | 75% |
| 3 | 8.1 hours | 12.5% | 87.5% |
| 4 | 10.8 hours | 6.25% | 93.75% |
| 5 | 13.5 hours | 3.13% | 96.88% |
| 6 | 16.2 hours | 1.56% | 98.44% |
| 7 | 18.9 hours | 0.78% | 99.22% |
Why do the numbers differ between sources?
Most of the variation in PT-141 figures comes from two places. The first is the spread between people, which the label states openly. The second is the gap between bremelanotide as an approved product and PT-141 as research-use material.
The label figure was measured with Vyleesi. Material sold as PT-141 outside that product is not the approved drug, and its identity, purity and formulation are unverified, so the label's pharmacokinetics cannot simply be assumed to apply. Melanotan II figures are sometimes substituted too, but melanotan II has no published human half-life at all.
What does a half-life not tell you?
It does not tell you how long the effect on desire lasts. Bremelanotide acts on central MC4R and MC3R pathways, and the label itself says the precise mechanism by which it improves sexual desire is not fully known. Plasma concentration and a central nervous system effect can come apart in either direction.
It also cannot describe effects that live in tissue rather than blood. Focal hyperpigmentation reflects activity at melanocortin receptors in the skin, and pigment is a tissue change, not a plasma level, so the half-life cannot tell you how long it persists.
Can you run the numbers yourself?
The estimator applies the same decay arithmetic to any half-life, starting amount and time you enter. It opens with PT-141's published value loaded. Type another figure to see how sensitive the result is to it.
Published value: Approximately 2.7 hours (range 1.9 to 4.0) (Subcutaneous) · Vyleesi label, DailyMed · Compound profile
Show the math
What are the limits of this estimate?
Everything above is a single-compartment approximation: one pool of drug, falling by the same fraction in every interval. Real elimination varies with kidney and liver function, body composition, formulation and route, and a published figure describes only the route and the people it was measured in. Many compounds also show a fast distribution phase before the slower elimination the table describes.
A half-life is not a dosing schedule. Labelled intervals come from clinical trials that measured outcomes and tolerability, and nothing on this page suggests when to take, repeat or stop anything. Whether PT-141 is out of your system for drug-testing purposes is a different question again. Tests often look for metabolites rather than the parent compound, and the answer depends on the assay, its sensitivity and the sample type, none of which a plasma half-life captures.
FAQ.
Is PT-141 the same as bremelanotide?
PT-141 is the research name for bremelanotide, which is approved as Vyleesi. The half-life on this page comes from the Vyleesi label. Material sold under the PT-141 name outside the approved product is not verified to match it.
Why does the PT-141 half-life have a range?
Because people differ. The label reports a mean terminal half-life of approximately 2.7 hours with a range of 1.9 to 4.0 hours after a single subcutaneous dose. The mean is useful for a table, but any one person's clearance could sit anywhere in that range, or outside it.
Does melanotan II have the same half-life as PT-141?
There is no human figure to compare. Our half-life reference lists melanotan II as having no reliable published human pharmacokinetics, only rat data. The bremelanotide figure belongs to bremelanotide and should not be read across to a related peptide.
For what the evidence on PT-141 actually shows, read the PT-141 profile. For approval and regulatory position, see is PT-141 legal. The half-life reference lists every sourced value side by side, including the compounds where a number circulates online with no reliable human data behind it.