Research documentation · Label findings · Section 05
PT-141 Dosage, Half-Life, and Duration in the Record
What the approved label and the trials specify — the 1.75 mg subcutaneous as-needed dose, the ~2.7 h half-life, and the frequency caps. Reported as documented findings, not as guidance.
The short version
This page reports the PT-141 dosage figures from the approved label and the trials — and only as findings, never as a protocol for anyone to follow. In the one approved use, bremelanotide is 1.75 mg injected just under the skin (subcutaneous), taken as needed before anticipated activity, with hard limits: no more than one dose per 24 hours and no more than eight per month. It clears the body fairly quickly — a terminal half-life (the time for the blood level to fall by half late in the curve) of about 2.7 hours. The dose-finding history and the duration details follow.
PT-141 Dosage in the Research and the Approved Label
The approved PT-141 dosage is documented precisely in the US prescribing information: bremelanotide 1.75 mg subcutaneously, as needed, at least 45 minutes before anticipated sexual activity, with no more than one dose per 24 hours and no more than eight doses per month [5]. This is reported here as a label finding — the figure the FDA approved for the HSDD indication — not as a recommendation for any individual.
The dose was not arbitrary. A randomized, placebo-controlled subcutaneous dose-finding trial evaluated 0.75, 1.25, and 1.75 mg in premenopausal women with female sexual dysfunction, and 1.75 mg was the dose advanced to Phase 3 [8]. Phase 2b responder analyses examined the proportion of women reaching clinically meaningful improvement across doses, supporting the benefit-risk basis for that selection [9]. Early intranasal research in men (a discontinued route) escalated to roughly 7-20 mg, with a statistically significant erectile response above 7 mg — investigational, off-label history, not a guide [1].
PT-141 Dosage for Women: the Approved 1.75 mg Regimen
The approved population is the only one with a labeled regimen. The PT-141 dosage for women with acquired, generalized HSDD — and only premenopausal women — is 1.75 mg subcutaneous as-needed, capped at one dose per 24 hours and eight per month [5][6]. The product is supplied as a ready-to-use subcutaneous autoinjector, not a powder requiring reconstitution [5].
This regimen is what the RECONNECT Phase 3 program tested (n=1267) and what the 52-week extension carried to a year [3][4]. It is documented as the approved finding for this specific population; it is not a dose for men, for postmenopausal women, or for any off-label purpose, and it is not guidance for a reader.
How Long Does PT-141 Last? Half-Life and Duration
How long does PT-141 last? Pharmacokinetically, the terminal half-life after subcutaneous administration is approximately 2.7 hours (range 1.9-4.0 h) per the US prescribing information [5]. Median Tmax — the time to peak concentration — is roughly 0.5-1.0 h after a subcutaneous injection [5]. Early intranasal studies reported a shorter half-life of 1.85-2.09 h [5].
The subjective duration is a different measurement than the blood-level half-life: the 2022 fMRI study found MC4R agonism increased sexual desire for up to 24 hours, a central effect that outlasts the drug's plasma presence [13]. Supporting pharmacokinetics from the label: volume of distribution ~25.0 L, clearance ~6.5 L/hr, serum protein binding ~21%, and excretion 64.8% renal / 22.8% fecal from a radiolabeled dose [5]. The cyclic lactam structure gives it greater stability than linear melanocortin peptides [6].
PT-141 Half-Life
To state the PT-141 half life on its own: approximately 2.7 hours (range 1.9-4.0 h) terminal half-life after subcutaneous dosing, per the prescribing information [5]. That is a short half-life for a peptide drug — consistent with its as-needed, before-activity dosing rather than a daily standing dose. The metabolism is by hydrolysis of the cyclic-peptide amide bonds and peptidase digestion [5]. See the full PT-141 dosage and half-life figures above; all are reported as label findings.
Routes studied
Three routes appear in the development record [5]. Subcutaneous is the approved route and the one carried through Phase 3 [3][5]. Intranasal was used in early development — including the male ED dose-escalation and the 2006 female arousal study [1][7] — but was discontinued due to pharmacokinetic variability [5]. Intravenous appeared in early pharmacology [5]. A Phase 1 obesity research protocol used subcutaneous dosing up to 2.5 mg, up to three times daily for 15 days — a research protocol only, well outside the approved as-needed regimen and named here strictly as documented history [5].