# PT-141 Dosage and Half-Life: The Label Figures and Pharmacokinetics > PT-141 dosage as reported: 1.75 mg subcutaneous as-needed (max 1/24h, 8/month). Terminal half-life ~2.7 h. The label and trial figures, reported as findings, not advice. What was studied and approved — the as-needed subcutaneous dose, the per-day and per-month limits, and the pharmacokinetics — set out as a record, never as a protocol to follow. ## The short version Here is the PT-141 dosage picture in plain terms. The approved figure for premenopausal women with HSDD is 1.75 mg, injected under the skin, only when needed — no more than once in 24 hours and no more than eight times a month [6]. It is taken at least 45 minutes before activity. It clears the body fairly fast: the terminal half-life (the time for the blood level to fall by half once it is mostly gone) is about 2.7 hours [6]. These are study and label numbers, reported as findings. This is not a dose anyone should copy — that is a decision for a qualified clinician. ## What is the PT-141 dosage? The approved label specifies 1.75 mg subcutaneously, as needed, no more than one dose per 24 hours and no more than eight per month, for premenopausal women with HSDD [6]. That single figure is reported here as the label and trial finding, not as guidance. Early intranasal male-ED research used much higher doses — escalation to roughly 7-20 mg — but that route was discontinued for pharmacokinetic variability and was never approved [7]. A separate Phase 1 obesity protocol administered up to 2.5 mg subcutaneously up to three times daily for 15 days; that is a research protocol only, not an approved or recommended regimen [6]. Across all of these, the figures describe what was studied — nothing here is a dose to follow. ## PT-141 dosage for women in the trials In the trials, the PT-141 dosage for women was 1.75 mg subcutaneous as-needed. In RECONNECT (n=1267) and the US label, premenopausal women with HSDD self-administered a single 1.75 mg subcutaneous injection as needed, at least 45 minutes before anticipated activity, capped at one dose per 24 hours and eight per month [3][6]. This dose came out of a randomized dose-finding trial comparing 0.75, 1.25, and 1.75 mg, with a Phase 2b responder analysis supporting the selection [10][11]. Reported as a finding, not a protocol. ## How long does PT-141 last? PT-141 has a short pharmacokinetic footprint. After subcutaneous injection, the median time to peak concentration (Tmax) is about 0.5-1.0 hour, and the terminal half-life is approximately 2.7 hours (range 1.9-4.0 h) per the US prescribing information [6]. Early intranasal studies reported a half-life of roughly 1.85-2.09 hours [7]. The label's instruction to dose at least 45 minutes before anticipated activity reflects this rapid onset. "How long it lasts" pharmacologically — a few hours in the blood — is distinct from how long a behavioral effect persists; the fMRI work reported increased desire for up to 24 hours in women with HSDD, a central effect that outlasts the plasma level [5][6]. ## Half-life of PT-141 The terminal half-life of PT-141 is approximately 2.7 hours (range 1.9-4.0 h) after subcutaneous administration, per the prescribing information [6]. Supporting pharmacokinetics from the label: volume of distribution about 25.0 L, clearance about 6.5 L/hr, serum protein binding around 21%, with metabolism by hydrolysis of the cyclic-peptide amide bonds and excretion split 64.8% renal and 22.8% fecal from a radiolabeled dose [6]. The cyclic lactam structure makes the peptide more stable than a linear melanocortin would be. ## How do you take PT-141? In the trials and the approved label, bremelanotide was self-administered as a single subcutaneous injection, as needed, at least 45 minutes before anticipated activity, with strict per-day (one) and per-month (eight) limits [6]. This describes the studied and approved route, reported as a finding. The approved product is supplied as a ready-to-use prefilled subcutaneous autoinjector, so there is nothing to mix or reconstitute. Reconstitution questions arise only for unapproved "research chemical" lyophilized powder, which is for laboratory use only and is not the approved finished drug; this site offers no preparation or dosing protocol for it. ## Routes studied and stability Three routes appear in the development record: subcutaneous (the approved route), intranasal (an early route, discontinued for pharmacokinetic variability), and intravenous (early pharmacology) [6][7]. The subcutaneous route is the one that carried through to approval. The molecule's cyclic lactam structure confers greater stability than a linear melanocortin peptide, which is part of why a once-as-needed subcutaneous dose is workable [6]. None of these route or dose facts is a recommendation; they describe what was investigated. --- PT-141 read as a raw instrument of record — the one approved use, the modest effect, and the nausea-led tolerability cost ruled into the page and cited line by line, with the unverified field reports fenced off behind a dashed border; no clinic behind the grid and nothing here dosed, sourced, or sold.