PT-141 Protocol

Dosing & Research

Last Updated: September 4, 2026

Chemical Identity

Amino Acid Sequence: Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH
Molecular Formula: C50H68N14O10
Molecular Weight: 1025.18 g/mol
CAS Number: 189691-06-3

Hypoactive sexual desire studies, Melanocortin receptor pharmacology, Female sexual function, Arousal signaling

Evidence Level

Human Clinical Data Available

Species Studied

Human • Rat • Mouse

Half-Life

~2.7 Hours

Administration

Subcutaneous

Frequency

As Needed

How It Works

Hypoactive sexual desire studies
Melanocortin receptor pharmacology
Female sexual function
Arousal signaling

Dosing Structure

Dose

200–500 mcg as needed, start at lower end)

Frequency

As Needed

Notes

Dose-sensitive: Start at 0.5mg and titrate up to 2mg based on response. Many individuals find 0.5–1mg sufficient; higher doses increase side-effect risk (nausea, flushing). Taken at least 45 minutes before activity. No specific cycle duration; should only be administered once every 24 hours with a maximum of 8 administrations per month. Expect individual variability on how fast effects are felt. Inject: SubQ abdomen (2 inches from navel) or upper thigh. Minimum 24 hours between doses.

Example Protocols

Dose: 200–500 mcg as needed, start at lower end)

Frequency: As Needed

Duration: As needed; max 8 administrations per month

Off Period: Not listed

Calculate dosing →

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Protocol Notes

•

Dose-sensitive: Start at 0.5mg and titrate up to 2mg based on response.

•

Many individuals find 0.5–1mg sufficient; higher doses increase side-effect risk (nausea, flushing).

•

Taken at least 45 minutes before activity.

•

No specific cycle duration; should only be administered once every 24 hours with a maximum of 8 administrations per month.

•

Expect individual variability on how fast effects are felt.

•

Inject: SubQ abdomen (2 inches from navel) or upper thigh.

•

Minimum 24 hours between doses.

What Is PT-141?

PT-141 (bremelanotide) is a melanocortin receptor agonist - a synthetic analogue of Melanotan II - that works centrally through MC3R and MC4R receptors in the brain to increase sexual desire and arousal. Unlike PDE5 inhibitors (Viagra, Cialis) that act peripherally on blood flow, PT-141 acts on the central nervous system to activate the sexual desire pathway. It is FDA-approved under the brand name Vyleesi for hypoactive sexual desire disorder (HSDD) in premenopausal women.

Research Observations - Not Medical Claims

▸FDA approval basis: Bremelanotide (Vyleesi) 1.75 mg subcutaneous auto-injector demonstrated statistically significant improvements in desire and reduced distress in HSDD in 2 Phase 3 RCTs (RECONNECT studies, n=1267) (PMID: 30865854).
▸Male sexual dysfunction: Phase 2 trials in men with erectile dysfunction showed bremelanotide produced erections in 80% of subjects with psychogenic ED and 73% with organic ED at 4–6 mg intranasal doses - without a stimulus requirement (PMID: 14974172).
▸Central mechanism confirmed: fMRI studies showed bremelanotide increased activity in limbic brain regions associated with sexual arousal, confirming central (not peripheral) mechanism of action.
▸Blood pressure: Transient blood pressure increase (mean +6 mmHg systolic) was observed - a key safety finding that led to contraindication in patients with high cardiovascular risk.
▸Nausea dose-response: Nausea is the primary dose-limiting side effect, occurring in 40% of subjects at 1.75 mg - significantly more at higher doses; this drove dose selection for FDA approval.