Tempo and decay
PT-141 Dosage and Half-Life: The Labeled Regimen, as a Finding
What the approved label and the trials specify for bremelanotide — the 1.75 mg subcutaneous as-needed dose, the limits, the timing, and the ~2.7 h half-life — reported as the studied record, never as instructions to follow.
The short version
This page reports the PT-141 dosage that appears in the approved label and the trials — and only as a finding, not as guidance for any reader. In the approved use (women before menopause with HSDD), the label dose is 1.75 mg injected just under the skin, taken as needed, at least 45 minutes before activity, with a hard ceiling of one dose per 24 hours and no more than 8 per month. The drug clears fairly fast — a half-life of roughly 2.7 hours. This site recommends no dose to anyone.
PT-141 Dosage for Women in the Approved Label
Reported strictly as the labeled regimen: in premenopausal women with HSDD, the approved dose is 1.75 mg subcutaneous (injected just under the skin), as needed, at least 45 minutes before anticipated sexual activity, with no more than one dose per 24 hours and no more than 8 doses per month [6]. That is the 1.75 mg label dose, and it is the same regimen carried through the RECONNECT trials [3].
The "as-needed" design is itself a finding worth reading. Unlike a daily medication, the labeled use is episodic — a dose taken ahead of anticipated activity rather than on a fixed schedule — and the per-day and per-month ceilings are part of the approved instructions, not optional guidance [6]. Phase 2 dose-finding had evaluated 0.75, 1.25, and 1.75 mg subcutaneously before 1.75 mg was settled on as the studied and approved dose [6].
Every figure here is a study and label finding [6][3]. None of it is a protocol for any individual, and this site recommends no dose for anyone. The dose is reported the way a score reports a tempo marking — a fact about how the piece was written, not an instruction handed to the reader.
How Long Does PT-141 Last? Half-Life and Duration
After subcutaneous administration, the terminal half-life is approximately 2.7 hours (range 1.9-4.0 h) per the US prescribing information, with median Tmax around 0.5-1.0 hour [6]. So the molecule reaches the blood quickly and clears within hours — the tempo behind the "at least 45 minutes before" timing instruction in the label [6].
Desire effects, by contrast, can outlast the molecule: the fMRI study recorded increased desire for up to 24 hours after a dose, a downstream central effect rather than continued drug presence [5]. The pharmacokinetic clock and the experienced-effect clock are not the same clock, which the score keeps distinct.
PT-141 Half-Life and the rest of the PK
The PT-141 half-life anchors a well-characterized pharmacokinetic profile. Per the label: terminal half-life ~2.7 h (range 1.9-4.0 h), volume of distribution ~25.0 L, clearance ~6.5 L/hr, ~21% serum protein binding, with excretion 64.8% renal and 22.8% fecal of a radiolabeled dose [6]. Early intranasal studies reported a shorter 1.85-2.09 h half-life on that discontinued route [6].
Metabolism proceeds by hydrolysis of the cyclic-peptide amide bonds and peptidase digestion — the body unpicking the ring [6]. The cyclic lactam structure is what confers greater stability than a linear melanocortin peptide in the first place, which is the chemistry behind a practical as-needed injection [1].
Routes studied and the research-chemical caveat
Subcutaneous is the approved route [6]. Early development also explored intranasal dosing — discontinued for pharmacokinetic variability — and intravenous administration in early pharmacology [6]. The intranasal route is where the early male erectile-dysfunction signal was generated, including dose-escalation work reporting a statistically significant erectile response above roughly 7 mg, but that route never became the approved formulation [1][6].
Higher-frequency and metabolic research protocols used different regimens entirely. A Phase 1 obesity study, for instance, administered subcutaneous doses up to 2.5 mg up to three times daily for 15 days — a research protocol only, and far outside the approved as-needed use [6]. The relevance is pharmacological, not practical: MC4R also sits in appetite circuits, so high-frequency dosing is where caloric-intake and body-weight effects surface, which is a property of the receptor target rather than an approved indication [6].
The approved finished product is a pre-formulated single-dose subcutaneous injection — not a reconstituted powder [6]. Material sold as "PT-141 research chemical" is for laboratory research only, sits outside the approval framework with no oversight of identity, purity, or concentration, and is not the approved drug [3]. For what these doses cost in tolerability, read the half-life and timing alongside the PT-141 side effects.