# PT-141 Dosage in the Research Literature: Label, Half-Life, and Pharmacokinetics > PT-141 dosage as a label finding: bremelanotide 1.75 mg subcutaneous as-needed for premenopausal-women HSDD, terminal half-life ~2.7 h, Tmax ~0.5-1.0 h. Reported as research, not as a protocol for any reader. The approved label specifies 1.75 mg subcutaneous, as needed. The terminal half-life is about 2.7 hours. Every figure here is reported as a study or label finding — never as a protocol for any individual. ## Before the details This page reports the PT-141 dosage and pharmacokinetics (how the body absorbs and clears the drug) exactly as the trials and the FDA label describe them — and **only** that way. It does not recommend a dose for anyone. The approved drug, bremelanotide, is given as a 1.75 mg injection just under the skin, used as needed before anticipated activity, with strict limits: no more than one dose in 24 hours and no more than 8 a month. It clears the body fairly quickly — a half-life (the time for half the drug to leave) of about 2.7 hours. Whether and how a drug applies to a person is a clinician's decision, not something a website should script. ## PT-141 Dosage for Women in the Approved Label For the approved HSDD indication in premenopausal women, the US prescribing information specifies **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 8 doses per month [6]. That dose was selected from Phase 2 subcutaneous dose-finding in women, which evaluated **0.75, 1.25, and 1.75 mg** [11]. The 1.75 mg as-needed regimen is what RECONNECT tested and what the label carries [3][6]. Reported here strictly as the label finding — this is the documented approved regimen for one population, not a protocol for any reader, and the dosing ceiling is tied in part to the cardiovascular profile covered on [the side-effects page](/side-effects) [6]. ## Half-Life and Pharmacokinetics of PT-141 After subcutaneous administration, bremelanotide has a **terminal half-life of approximately 2.7 hours (range 1.9-4.0 h)** per the US prescribing information [6]. Early intranasal studies in men reported a shorter half-life of 1.85-2.09 hours for that route [7]. The broader pharmacokinetic profile from the label: volume of distribution ~25.0 L; clearance ~6.5 L/hr; about 21% serum protein binding; metabolism by hydrolysis of the cyclic-peptide amide bonds and peptidase digestion; and excretion split 64.8% renal and 22.8% fecal of a radiolabeled dose [6]. The cyclic lactam ring confers **greater stability** than linear melanocortin peptides — the structural feature that made the molecule a viable drug [6]. ## How Long Does PT-141 Last? Pharmacokinetically, PT-141 acts and clears on a short timeline. Median **Tmax** — time to peak concentration — is about **0.5 to 1.0 hours** after subcutaneous injection [6], which is why the label specifies dosing at least 45 minutes before anticipated activity [6]. With a terminal half-life near **2.7 hours**, the bulk of the compound is cleared within a workday [6]. The behavioral effect, however, can outlast the drug in plasma: the 2022 fMRI study found that MC4R agonism increased sexual desire for **up to 24 hours** — desire and drug concentration are not the same clock [5]. The as-needed, episodic design follows directly from this short pharmacokinetic window [6]. ## Routes studied and the research-dose context Three routes appear in the literature: **subcutaneous** (the approved route), **intranasal** (early development, discontinued for PK variability), and **intravenous** (early pharmacology) [6][7][8]. Doses across the research record, reported as findings: the approved 1.75 mg SC as-needed (women, HSDD) [6]; Phase 2 SC dose-finding at 0.75 / 1.25 / 1.75 mg (women) [11]; early intranasal dose-escalation in men to roughly 7-20 mg, with a statistically significant erectile response above 7 mg [7]; and a Phase 1 obesity research protocol in women using subcutaneous doses up to 2.5 mg, up to three times daily for 15 days — a research protocol only, and a reminder that high-frequency dosing engages the MC4R appetite pathway [11]. None of these are instructions; they are the documented doses studied. The male-route research is detailed on [PT-141 for men (off-label research)](/pt-141-for-men). ## How is PT-141 supplied, and the reconstitution question The approved bremelanotide product is a **ready-to-use prefilled subcutaneous autoinjector** — not a powder that a patient reconstitutes [6]. Reconstitution questions arise around the unapproved "research chemical" lyophilized (freeze-dried) form, which is laboratory material only and is not the finished drug product [11]. This site describes the literature and the label, not preparation steps. The distinction matters: the approved finished drug and laboratory "PT-141" are not interchangeable, and material sold as a research chemical carries no regulatory assurance of identity, purity, or concentration [11]. --- The PT-141 (bremelanotide) record folded into clean planes — the one approved use creased apart from the off-label male research, the modest effect set beside the number that qualifies it, and the nausea-led tolerability cost read in plain sight, with the unverified field reports tucked behind a dashed fold; no clinic behind the paper and nothing here dosed, dispensed, or sold.