Kisspeptin-10 vs PT-141

Kisspeptin-10

Kisspeptin is the product of the KISS1 gene acting on the receptor KISS1R (formerly GPR54). It sits upstream of the hypothalamic-pituitary-gonadal axis: it is the trigger for pulsatile GnRH release from the hypothalamus, and therefore for LH and FSH from the pituitary and testosterone or oestradiol downstream. The pathway was found because loss-of-function KISS1R mutations cause hypogonadotropic hypogonadism. That position upstream is the whole point of the compound and also the reason to be careful with it - it does not act locally, it moves an entire endocrine axis. Unusually for this dataset, the human data is real and well controlled. Research groups, notably Dhillo and colleagues at Imperial College London, have given kisspeptin-10 and the longer kisspeptin-54 to healthy men and women by intravenous bolus, intravenous infusion and subcutaneous injection and measured the LH response directly with timed blood draws; separate fMRI work has examined limbic responses to sexual and emotional stimuli. A bolus of roughly 0.3 nmol/kg of kisspeptin-10 - about 25 to 30 mcg for a 70 kg adult - raises LH within tens of minutes, and that is where the 25 mcg floor here comes from. The typical 50 mcg figure sits just above that research bolus. The 200 mcg ceiling reflects the upper end of what grey-market users report, not a dose with controlled support; nothing above the research bolus has been shown to give a better response. Two caveats matter more than the number. First, the response desensitises: continuous or very frequent exposure downregulates the GnRH response instead of amplifying it, which is why intermittent dosing is the rational pattern and why more is not better. The every-other-day default here reflects that, not a trial protocol. Second, all of the human work is acute. There is no approved kisspeptin product anywhere, no long-term safety data, and nothing published on what repeated self-administration does to the axis over months, which is why no cycle length is given. Clearance is fast - kisspeptin-10 is cleared within a few minutes and kisspeptin-54 in roughly half an hour - so no hourly half-life is listed. Sensitivity differs between men and women and, in women, across the menstrual cycle. Note also that a 10 mg vial is far larger than a single dose: even reconstituted in 5 mL, 50 mcg is about 2.5 units on a U-100 syringe, so accurate measurement needs care or a further dilution.

PT-141 (Bremelanotide)

A melanocortin receptor agonist approved by the FDA in 2019 as Vyleesi for acquired, generalised hypoactive sexual desire disorder in premenopausal women. The label dose is 1.75 mg (1750 mcg) subcutaneously into the abdomen or thigh, taken AS NEEDED at least 45 minutes before anticipated sexual activity, with no more than one dose in 24 hours and no more than 8 doses per month. Phase 2 dose-ranging also studied 0.75 and 1.25 mg, which is where the 750 mcg floor here comes from; nothing above the 1.75 mg label dose is supported. IMPORTANT: this is not a scheduled compound. The scheduler stores it as 2x-week purely because that is the closest available slot to the label ceiling of 8 doses per month - do not read it as an instruction to dose on fixed days. Dose only before intended activity. The label contraindicates use in uncontrolled hypertension or known cardiovascular disease, a flag this dataset has no field for, so check blood pressure before starting. Efficacy in men is not established; use outside premenopausal women is off-label. The original intranasal formulation was abandoned in development after blood pressure increases, so the nasal route listed here reflects grey-market products, not an approved presentation.