# PT-141 Dosage in the Literature: Label, PK & Routes Studied > PT-141 (bremelanotide) dosage in the literature: the 1.75 mg label dose of record, half-life and pharmacokinetics, and the routes studied — described, never recommended. The pharmacology of record, drawn from the prescribing information and the trial protocols — described as documented facts, recommended to no one. ## The short version PT-141 dosage, stated as documented fact: the approved product is 1.75 mg given as an injection just under the skin, used only as needed — at most once in 24 hours, at most eight times a month, taken at least 45 minutes before anticipated activity [7]. That is the dose of record from the U.S. label for the one approved use (HSDD in premenopausal women), not advice. The drug acts fast and clears fast: peak blood levels arrive within about half an hour to an hour, and it is mostly gone within a handful of hours, which fits an as-needed product [7]. It was developed first as a nasal spray, then moved to the under-the-skin route because the spray's absorption was too variable [9]. Everything below is the pharmacology on the page — half-life, the figures, the routes — described so a reader understands the drug, with no instruction to take anything. ## PT-141 dosage: the label figures The authoritative numbers come from the prescribing information. The approved dose is 1.75 mg subcutaneous, as needed, at least 45 minutes before anticipated sexual activity, with a maximum of one dose per 24 hours and eight doses per month [7]. The same 1.75 mg as-needed dose ran through both pivotal Phase 3 trials [3], and Phase 2 dose-finding had tested 0.75, 1.25, and 1.75 mg before settling on the highest [7]. The frequency cap is part of the dose, not an afterthought: limiting how often the drug is used keeps it away from the higher-frequency dosing where hyperpigmentation, appetite, and blood-pressure effects become more prominent [7]. None of this is a recommendation; it is the dosing of record, reported as such. ## PT-141 injection: route and pharmacokinetics The PT-141 injection of record is subcutaneous. After a subcutaneous dose, the median time to peak concentration is roughly 0.5–1.0 hours [7]. The label documents a volume of distribution near 25 L, clearance around 6.5 L/hr, about 21% serum protein binding, and excretion that is roughly 65% renal and 23% fecal from a radiolabeled dose [7]. Metabolism proceeds by hydrolysis of the cyclic-peptide bonds and ordinary peptidase digestion [7]. The cyclic lactam structure — the closed ring — gives the molecule more stability than a straight-chain melanocortin peptide, part of why a single as-needed injection is viable [7]. A 2025 delivery-science paper even reported about 26% relative bioavailability of bremelanotide via a biodegradable buccal (inside-the-cheek) patch compared with subcutaneous injection, an early proof-of-concept for non-injected routes [15]. ## How long does PT-141 last PT-141 clears quickly. The terminal half-life — the time for blood levels to fall by half once the drug is clearing — is approximately 2.7 hours after subcutaneous administration, with a reported range of 1.9–4.0 hours [7]. Early intranasal studies reported a similar 1.85–2.09 hours [7]. A short half-life does not mean a short-lived effect, and the distinction matters for desire. In the brain-imaging study, MC4R agonism increased sexual desire for up to 24 hours even though the drug itself had largely cleared — the molecule initiates a central change that outlasts its presence in the blood [5]. So "how long PT-141 lasts" has two answers: hours in the bloodstream, but a desire effect measured out to a day in that study. ## Routes studied and the approval boundary Three routes appear in the record. Subcutaneous is the approved route and the basis for the label PK [7]. Intranasal was the original development route and was discontinued for pharmacokinetic variability [9]. Intravenous was used in early pharmacology [7]. None of this is a menu of options for any person. The approval boundary applies to dosing too. The 1.75 mg subcutaneous schedule is approved only for premenopausal women with HSDD [7]. The product also carries a contraindication: it is not to be used by people with uncontrolled hypertension or known cardiovascular disease, because of documented transient blood-pressure increases [7]. And "PT-141 research chemical" sold outside that framework has no verified strength, so any figure on its label is unreliable [7]. This page reports the studied doses and the label PK as facts and recommends no dose to anyone. --- A regulatory-careful reading room on PT-141 (bremelanotide): the single 2019 approval for premenopausal HSDD held distinct from every off-label and research-chemical use, each figure logged to the trials or the FDA label — a reading desk organized around the prescription record, never a place that writes, fills, or fulfils one.