# PT-141 Dosage and Half-Life: The Label Regimen and the Pharmacokinetics

> PT-141 dosage as reported on the label and in the trials: 1.75 mg subcutaneous as-needed (max 1/24h, 8/month), terminal half-life ~2.7 h. Reported as findings, not a protocol to follow.

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](/dosage) 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].

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A precision-metrology readout of the bremelanotide record — each measured value logged to its study and tagged in-spec or disputed, the effect-size debate kept beside the number it qualifies and the field reports fenced off the calibrated panel; no clinic behind the instrument and nothing here dosed, dispensed, or sold.