Pt-141 Half Life
PT-141 Half Life: Bremelanotide Pharmacokinetics
The short answer
PT-141 half life, per the FDA Vyleesi label, is a mean terminal half life for bremelanotide of about 2.7 hours, with a stated range of roughly 1.9 to 4.0 hours (FDA Vyleesi label).
This page is general educational information, research-use framing only, not medical advice. Any decision about a research compound belongs with a qualified clinician.
What is the half life of PT-141 (bremelanotide)?
The FDA Vyleesi label reports a mean terminal half life of about 2.7 hours for bremelanotide, with a stated range of roughly 1.9 to 4.0 hours (FDA Vyleesi label).
Half life is the time it takes for the plasma concentration of a compound to fall by half after it reaches peak levels. A half life near 2.7 hours places bremelanotide in the short-acting category compared with many longer-lived peptides. In practical PK terms, most of a single dose is cleared from circulation within roughly a day, since a compound is largely eliminated after about four to five half lives.
The number itself comes from the pharmacokinetic section of the approved subcutaneous bremelanotide product label, which pooled data from its clinical program (FDA Vyleesi label).
What are the full pharmacokinetics of bremelanotide?
Published PK for subcutaneous bremelanotide shows fast absorption, a short half life, and clearance through both urine and feces (FDA Vyleesi label).
The table below summarizes the values reported in the label. All figures are research-reported, not instructions.
| Parameter | Reported value | Source |
|---|---|---|
| Terminal half life | about 2.7 hours (range 1.9 to 4.0 h) | FDA Vyleesi label |
| Time to peak (Tmax) | median about 1.0 hour | FDA Vyleesi label |
| Route studied | subcutaneous | FDA Vyleesi label |
| Plasma protein binding | about 21 percent | FDA Vyleesi label |
| Primary elimination routes | urine (majority) and feces | FDA Vyleesi label |
Because absorption is fast and the half life is short, plasma levels rise within about an hour and then decline over the next several hours (FDA Vyleesi label).
Does half life tell you how long PT-141 works?
No; half life measures clearance from the blood, not the duration of any biological response.
A compound can leave circulation while a receptor-driven effect persists, or an effect can be shorter than the drug's presence. Bremelanotide acts as a melanocortin receptor agonist, and receptor signaling does not track plasma concentration one to one (Kingsberg et al., 2019). So the roughly 2.7 hour half life describes pharmacokinetics, the movement of the compound, not pharmacodynamics, the response. Anyone reading a half life figure as an effect timer is mixing two separate measurements.
What did the clinical program report about bremelanotide?
The pivotal subcutaneous phase 3 program (the RECONNECT trials) reported a recognizable side-effect profile, with nausea as the most common event, affecting about 40 percent of participants (Kingsberg et al., 2019).
The two randomized phase 3 trials studied subcutaneous bremelanotide as a melanocortin agonist. Alongside the efficacy endpoints, the trials documented tolerability signals, and nausea stood out at roughly 40 percent of treated participants (Kingsberg et al., 2019). These are outcomes reported in the trials, not predictions of what any individual would experience.
Earlier research also studied an intranasal formulation of bremelanotide in men, using a different route and different endpoints. Evidence from that earlier intranasal work is limited, and its tolerability numbers are not interchangeable with the subcutaneous phase 3 data and should be read separately.
How does a short half life compare with longer-acting peptides?
A half life near 2.7 hours is short; several research peptides studied for other endpoints stay active far longer.
For context only, growth hormone secretagogues and analogs studied in separate research show much longer signaling windows. CJC-1295 produced sustained growth hormone and IGF-1 elevations across days in its published work (Teichman et al., 2006), and tesamorelin was studied over weeks-long dosing periods for visceral fat endpoints (Falutz et al., 2007). These are different compounds with different targets, listed only to frame what "short" versus "long" means in PK terms. None of this is a comparison of use or a suggestion to combine anything.
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References
- Vyleesi (bremelanotide injection) Prescribing Information. FDA-approved label. Clinical pharmacology section. Source for the mean terminal half life of about 2.7 hours (range about 1.9 to 4.0 hours), a median time to peak concentration of about 1.0 hour after subcutaneous administration, plasma protein binding of about 21 percent, and elimination through urine and feces.
- Kingsberg SA, Clayton AH, Portman D, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstet Gynecol. 2019;134(5):899 to 908. doi:10.1097/AOG.0000000000003500 (PMID 31599840). Source for the pivotal subcutaneous phase 3 program reporting nausea in about 40 percent of participants and for bremelanotide acting as a melanocortin receptor agonist.
- Teichman SL, Neale A, Lawrence B, et al. Prolonged Stimulation of Growth Hormone and Insulin-Like Growth Factor I Secretion by CJC-1295, a Long-Acting Analog of GH-Releasing Hormone, in Healthy Adults. J Clin Endocrinol Metab. 2006;91(3):799 to 805. (PMID 16352683). Cited only to frame duration in pharmacokinetic terms, showing sustained growth hormone and IGF-1 elevations across days.
- Falutz J, Allas S, Blot K, et al. Metabolic Effects of a Growth Hormone-Releasing Factor in Patients with HIV. N Engl J Med. 2007;357(23):2359 to 2370. doi:10.1056/NEJMoa072375 (PMID 18057338). Cited only for context, referencing tesamorelin studied over weeks-long dosing periods for visceral fat endpoints.
General educational information only, research-use framing, not medical advice. Confirm the current status where you live and consult a qualified professional before acting.