PT-141

PT-141 (bremelanotide) is a cyclic heptapeptide analog of alpha-MSH. It has completed a Phase III program and is approved in the United States for hypoactive sexual desire disorder in premenopausal women.

Unlike phosphodiesterase inhibitors, which act peripherally on vascular smooth muscle, bremelanotide is a non-selective melanocortin receptor agonist acting primarily on MC4R in hypothalamic and limbic circuits that regulate sexual motivation.

Store the sealed lyophilized vial at 2-8 °C, protected from light; brief exposure to room temperature during shipping is generally tolerated. Refrigerate after reconstitution at 2-8 °C and use within the period supported by stability data for the substance (typically 2-4 weeks). Avoid repeated freeze-thaw cycles: each cycle increases the risk of aggregation and hydrolysis of the peptide bond. Do not shake the vial; swirl gently and direct the liquid stream against the glass wall rather than at the powder cake.

• Sealed lyophilized vial, stored as supplied
• Bacteriostatic water (0.9% benzyl alcohol) for reconstitution
• Insulin syringes (29-31G, 0.5 mL / 100 units)
• Reconstitution syringe (1-3 mL, 21-23G needle)
• 70% isopropyl alcohol swabs
• Sharps container for used needles
• Labels and a logbook for batch, date and volume

RECONNECT Phase III trials reported statistically significant improvements in desire and distress scores. Common adverse effects include nausea (approximately 40%), flushing and headache; transient increases in blood pressure and decreases in heart rate were observed, and focal hyperpigmentation is reported with repeated dosing.

Wash your hands, then disinfect the vial septum and the injection site with 70% isopropyl alcohol and allow both to air dry. Draw up the intended volume, remove air bubbles and pinch a subcutaneous skin fold. Insert at a 45-90° angle depending on fat thickness, aspiration is not required for subcutaneous administration, and inject slowly. Withdraw the needle, apply light pressure and discard the needle in a sharps container. Rotate injection sites systematically (abdominal quadrants, flanks, thighs) to prevent lipohypertrophy and local irritation.

Peptide research protocols are studied against a background of adequate protein intake (approximately 1.6-2.2 g/kg/day in the training literature), consistent sleep of 7-9 hours, and controlled training load. Sleep deprivation and chronic psychological stress both dampen growth hormone pulsatility and disrupt tissue remodeling, complicating the interpretation of any observed effect. Alcohol, smoking and large caloric deficits are likewise documented modifiers of recovery outcomes.

1. Kingsberg S.A. et al. Bremelanotide for hypoactive sexual desire disorder (RECONNECT). Obstet Gynecol, 2019.
2. Clayton A.H. et al. Bremelanotide safety and tolerability. J Sex Med, 2019.
3. Molinoff P.B. et al. PT-141: a melanocortin agonist for sexual dysfunction. Ann N Y Acad Sci, 2003.