§06 · Doses studied
PT-141 Dosage and Pharmacokinetics
The approved-label dose, the PK spec, and the doses studied in research — documented, not prescribed.
The short version
PT-141 dosage has one number that comes from the FDA-approved label and several others that come from research studies — and a careful reader should not blur the two. This page documents what was administered, to whom, by which route. It recommends nothing for any individual.
The approved drug, bremelanotide, is labeled at 1.75 mg injected under the skin, used as needed, with hard limits: no more than one dose per 24 hours and no more than eight per month [7]. Its half-life — the time for blood levels to fall by half — is about 2.7 hours [7]. Research has explored other doses and routes that never became approved uses, including intranasal dosing in men and higher experimental doses. All of that follows below, each line tied to its source.
PT-141 dosage — the approved label spec
The PT-141 dosage that carries an FDA label is precise and bounded. The US prescribing information for bremelanotide injection specifies a 1.75 mg subcutaneous dose, taken as needed at least 45 minutes before anticipated activity, with a maximum of one dose per 24 hours and no more than eight doses per month, for acquired generalized HSDD in premenopausal women [7].
Those frequency caps are part of the label, not optional fine print. The label also carries a warning on transient blood-pressure increase and contraindicates use in uncontrolled hypertension or cardiovascular disease [7]. This is documentation of the approved label, presented as a spec — not a recommendation for any individual to use any amount.
PT-141 dosage for women
The PT-141 dosage for women that the FDA reviewed is the 1.75 mg subcutaneous as-needed dose described above, studied in premenopausal women with HSDD [7]. Before that dose was chosen, Phase 2 subcutaneous dose-finding in women evaluated 0.75 mg, 1.25 mg, and 1.75 mg, and 1.75 mg became the approved dose [10].
The preclinical basis for a female indication came first from rodent work: in female rats, PT-141 selectively increased solicitational (desire-driven) behavior, pointing to a central melanocortin role in female sexual desire [2]. Note that this 1.75 mg figure applies to the approved premenopausal-HSDD indication only; it is not an approved dose for any other group or purpose [10].
How long does PT-141 last
How long does PT-141 last is a pharmacokinetics question, and the label answers it. After subcutaneous injection, bremelanotide reaches peak blood levels (Tmax) in roughly 0.5 to 1.0 hours, and its terminal half-life is approximately 2.7 hours (range 1.9 to 4.0 hours) [7]. Early intranasal studies reported a similar half-life of about 1.85 to 2.09 hours [10].
The broader PK spec: volume of distribution about 25.0 L, clearance about 6.5 L/hr, roughly 21% serum protein binding, with excretion split 64.8% renal and 22.8% fecal [7]. Functionally, the desire effect can outlast the drug's presence in blood — the fMRI study found increased desire for up to 24 hours after dosing [5], a reminder that a short plasma half-life does not equal a short central effect.
Doses and routes studied in research
Beyond the approved label, the research record explored doses and routes that never reached approval, and documenting them is part of an honest datasheet. Early intranasal research in men with ED used dose-escalation to roughly 7-20 mg, with statistically significant erectile responses above 7 mg [1]. A Phase 1 metabolic protocol in women administered up to 2.5 mg subcutaneously, up to three times daily for 15 days — a research protocol only, not a use pattern for any individual [11].
The routes studied span subcutaneous (the approved route), intranasal (discontinued in development for pharmacokinetic variability), and intravenous (early pharmacology) [10]. The cyclic lactam structure gives PT-141 greater stability than linear melanocortin peptides, which is part of why the subcutaneous route proved workable [10].