Pharmacokinetics · Label and trials
PT-141 Dosage and Half-Life: The Label Regimen and the PK
What the trials administered and what the label specifies — reported as findings, never as a protocol for anyone to follow.
The short version
This page reports the PT-141 dosage that appears in the trials and on the label — as facts, not as instructions. The approved drug, bremelanotide, is 1.75 mg injected just under the skin (subcutaneous), taken as needed at least 45 minutes before activity, with hard caps: no more than one dose per 24 hours and no more than eight per month [6]. It clears the body fast, with a half-life of about 2.7 hours, though a brain-imaging study found increased desire lasting up to 24 hours. This site does not recommend a dose for any person; the approved drug is a clinical decision made with a prescriber.
PT-141 Dosage in the Research and on the Label
The PT-141 dosage on the label is precise: 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 regimen — for the approved HSDD indication in premenopausal women — is reported here strictly as a label finding, not as a protocol for a reader to follow.
The dose-finding behind it evaluated 0.75, 1.25, and 1.75 mg in Phase 2 before the 1.75 mg strength advanced [6]. In the trials, bremelanotide was self-administered as a subcutaneous injection (abdomen or thigh) [6]. Material sold as "PT-141 research chemical" is for laboratory use only and is not the approved finished product; this site gives no preparation or self-administration protocol for human use.
PT-141 Dosage for Women in the RECONNECT Trials
In premenopausal women with HSDD — the approved and studied population — the dose is 1.75 mg subcutaneous, as needed, no more than once per 24 hours and no more than 8 times per month [6]. This is the regimen carried through the two pivotal RECONNECT trials (n=1267) and the 52-week open-label extension (684 women), where the same as-needed schedule was used over a year [3][4]. Reported as a trial and label finding only; this is not a personal protocol, and any use is a clinical decision made with a prescriber for the approved indication.
PT-141 Half-Life
The terminal half-life of PT-141 is approximately 2.7 hours (range 1.9-4.0 h) after subcutaneous administration, per the US prescribing information [6]. Early intranasal studies reported a shorter half-life of 1.85-2.09 h [6]. Median Tmax — the time to peak concentration — is about 0.5-1.0 h after subcutaneous injection [6].
Supporting pharmacokinetics: volume of distribution ~25.0 L, clearance ~6.5 L/hr, and ~21% serum protein binding [6]. Metabolism proceeds by hydrolysis of the cyclic-peptide amide bonds, and excretion is 64.8% renal and 22.8% fecal from a radiolabeled dose [6]. The cyclic lactam structure confers greater stability than linear melanocortin peptides [1].
How Long PT-141 Lasts
Two timescales matter and they differ. Pharmacokinetically, PT-141 is short-acting — the PT-141 half-life is ~2.7 h (range 1.9-4.0 h), with median Tmax ~0.5-1.0 h [6]. The drug is largely cleared within hours.
The behavioral effect outlasts the drug's presence: in the fMRI study, MC4R agonism increased reported sexual desire for up to 24 hours after a single dose [5]. That gap — a few-hour half-life but a desire effect lasting up to a day — reflects that the action is on central circuitry, not a sustained drug level. The label's 45-minute pre-activity timing reflects the rapid onset, not the duration of effect [6].