Frequently asked · PT-141
PT-141 FAQ: Bremelanotide, Mechanism, and Dosage
Direct answers to the most common PT-141 questions, cited to the studies and the label where a number is involved.
What is PT-141?
PT-141 is the research designation for bremelanotide, a synthetic cyclic heptapeptide analogue of alpha-MSH that activates central melanocortin MC3R/MC4R receptors [1]. It is FDA-approved (2019) only for HSDD in premenopausal women; all other uses are off-label [6].
What is PT-141 peptide?
It is a seven-amino-acid cyclic peptide — the cyclic lactam analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) [1]. The ring structure makes it more stable than linear melanocortin peptides, which is part of why it is dosable as a subcutaneous injection [6].
What does the PT-141 peptide do?
It activates melanocortin MC3R/MC4R receptors in the hypothalamus and limbic system, engaging brain circuits for sexual desire and arousal rather than acting on blood flow the way PDE-5 inhibitors do [1]. A human fMRI study showed it increased reported desire for up to 24 hours [5].
What is PT-141 used for?
Its single FDA-approved use is acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women [6]. Use in men, for erectile dysfunction, or in postmenopausal women is off-label and, for the male/erectile setting, still investigational [1].
Is PT-141 the same as bremelanotide?
Yes. PT-141 is the development and research designation; bremelanotide is the international nonproprietary name (INN) for the same molecule — the melanocortin receptor agonist approved for HSDD [6]. They are two names for one compound, CAS 189691-06-3 [1].
What is bremelanotide?
Bremelanotide is the approved-drug name for PT-141: a melanocortin MC3R/MC4R agonist approved in June 2019 (NDA 210557) as a 1.75 mg subcutaneous as-needed injection for HSDD in premenopausal women [6].
How does PT-141 work?
It stimulates melanocortin MC4R (and MC3R) receptors in hypothalamic circuits such as the medial preoptic area, engaging dopaminergic pathways tied to sexual motivation [1]. An fMRI study showed MC4R agonism altered brain processing of erotic stimuli and increased desire for up to 24 hours [5].
What receptors does PT-141 act on?
Chiefly the melanocortin 4 receptor (MC4R), with secondary MC3R activity, concentrated in central nervous system circuits [1]. Peripheral MC1R activation underlies the hyperpigmentation seen with repeated dosing [6].
Does PT-141 work through the brain or through blood flow?
Through the brain. Unlike PDE-5 inhibitors, which act peripherally on vascular smooth muscle, PT-141 works centrally on the neural circuitry of sexual desire and arousal [1]. The human fMRI evidence shows a central processing change, not a vascular one [5].
What is a melanocortin receptor agonist?
A compound that activates one or more of the five melanocortin receptors (MC1R-MC5R) [1]. PT-141 targets the central MC3R/MC4R subtypes, which is how it influences sexual desire [1].
Does PT-141 increase testosterone?
No. A common misconception is that PT-141 raises testosterone or acts through the HPG axis. It acts centrally on melanocortin receptors and does not directly raise testosterone, and it is not a PDE-5 inhibitor [11].
How is PT-141 different from PDE-5 inhibitors?
PDE-5 inhibitors work peripherally on blood vessels to support erection; PT-141 works centrally in the brain on melanocortin circuits governing desire and arousal [1]. The mechanisms are distinct, which is why a combination approach is being investigated for erectile dysfunction [14].
What is the PT-141 dosage?
Reported as a finding, not a recommendation: the approved label specifies 1.75 mg subcutaneously, as needed at least 45 minutes before anticipated activity, with no more than one dose per 24 hours and no more than 8 doses per month [6].
How much PT-141 should I take?
This site does not recommend a dose for any individual. The studied and approved amount is 1.75 mg subcutaneous as-needed in the HSDD trials [6]; any use is a clinical decision made with a prescriber for the approved indication.
How much PT-141 to inject?
As a research and label finding only: the approved subcutaneous dose studied was 1.75 mg per administration, capped at one dose in 24 hours [6]. Phase 2 dose-finding evaluated 0.75, 1.25, and 1.75 mg [6].
What is the PT-141 dosage for women?
In premenopausal women with HSDD, the approved and studied dose is 1.75 mg subcutaneous, as needed, no more than once per 24 hours and no more than 8 times per month [6]. Reported as a trial and label finding, not a personal protocol [3].
How do you reconstitute PT-141?
The approved finished product is a pre-formulated single-dose subcutaneous injection, so the labeled drug is not reconstituted by the patient [6]. Material sold as "PT-141 research chemical" is for laboratory use only and is not the approved drug; this site gives no preparation protocol for human use.
How do you take PT-141?
In the trials and on the label, bremelanotide was self-administered as a subcutaneous injection (abdomen or thigh) as needed at least 45 minutes before anticipated activity [6]. Described here as a study and label finding only.
How often can you take PT-141?
The label limits dosing to no more than one 1.75 mg dose per 24 hours and no more than 8 doses per month [6]. The 52-week extension study used the same as-needed schedule over a year [4].
What is the approved bremelanotide dose?
1.75 mg subcutaneously, as needed, with a maximum of one dose per 24 hours and 8 doses per month, per the US prescribing information for the HSDD indication in premenopausal women [6].
How long does PT-141 last?
Its terminal half-life is about 2.7 hours (range 1.9-4.0 h) after subcutaneous dosing per the label, with median Tmax around 0.5-1.0 hour [6]. In an fMRI study, MC4R agonism increased reported sexual desire for up to 24 hours [5].