PT-141 nasal spray is searched as though it were a second form of Vyleesi. It is the form that came first and was abandoned. Palatin Technologies ran its early bremelanotide trials as a nasal spray, at 7.5 to 20 mg a dose, and then switched to injection because the spray raised blood pressure and absorbed unevenly. The approved product, Vyleesi, is the injection at 1.75 mg. This page sets out the nasal record, what the developer said about it, and the per-spray arithmetic for anyone reading a compounded or vendor label.
The labelled dose, the subcutaneous trials and the per-vial units are on the PT-141 dosage page, and the vial preparation is on PT-141 reconstitution. PT-141 is compared with another libido peptide on kisspeptin vs PT-141, and its parent melanocortin line is on the melanotan 2 dosage page.
The nasal trials, dose by dose
| Study | Subjects | Intranasal dose | Reported result |
|---|---|---|---|
| Diamond et al. 2004 (Palatin) | Healthy men and men with mild-to-moderate ED | Escalating doses | Erections vs placebo significant above 7 mg; Tmax 0.5 h, half-life 1.85–2.09 h |
| Diamond et al. 2005 (Palatin) | 19 men with ED, crossover | 7.5 mg with sildenafil 25 mg | Greater erectile response than sildenafil alone |
| Diamond et al. 2006 (Palatin) | 18 premenopausal women | 20 mg single dose | More reported desire than placebo; no change in measured vaginal blood flow |
| Safarinejad 2008 | 342 men not helped by sildenafil | 10 mg, 45 min–2 h before | 33.5% vs 8.5% positive response; expression of concern published 2023 |
| Clayton et al. 2017 | Healthy volunteers with alcohol | 20 mg | No meaningful interaction with alcohol reported |
ClinicalTrials.gov holds one registration of the nasal programme, NCT00425256, an eight-week at-home phase 2 study in women started in February 2006 and completed in May 2007. A 2008 paper on women by the same lead author as the 342-man trial was retracted (PMID 18179455).
Why the spray was dropped, in Palatin's words
Palatin's 10-K for the fiscal year ended 30 June 2009 states it plainly. Blood-pressure increases were observed in some patients receiving the nasal form and were "a significant factor" in discontinuing it as a first-line therapy. The company attributed those increases, and the rate of nausea and vomiting, "at least partially, to variability in drug uptake with nasal administration", and wrote that studies "showed significant variation in plasma levels". A subcutaneous phase 1 study then showed no significant blood-pressure difference from placebo and lower variability in exposure, and the programme moved to injection.
That history is the context for every nasal figure in circulation now. The developer had the spray, at doses four to eleven times the eventual label, and gave it up because absorption through the nose was not consistent from dose to dose.
Nasal and injected doses side by side
| Figure | Route | Multiple of 1.75 mg |
|---|---|---|
| 1.75 mg (Vyleesi label) | Subcutaneous | 1× |
| 7.5 mg (with sildenafil, 2005) | Intranasal | 4.3× |
| 10 mg (2008 trial) | Intranasal | 5.7× |
| 20 mg (2006, 2017) | Intranasal | 11.4× |
| 1–2 mg per spray (vendor and compounded pages) | Intranasal | 0.6–1.1× per spray; no trial |
The label reports the injection's absolute bioavailability as about 100%. No absolute figure for the nose was found in the papers read for this page, so the ratio between a nasal milligram and an injected milligram is not established. The trials' dose levels and Palatin's account of variable plasma levels are the evidence that it is not one to one.
Per-spray arithmetic
A nasal spray's dose is concentration × the volume one pump stroke meters. Many metered nasal pumps deliver about 0.1 mL per actuation; that figure is used below as a stated assumption, and the number printed on a given pump replaces it.
| Vial and water | Concentration | mg per 0.1 mL spray | Sprays for 1.75 mg |
|---|---|---|---|
| 10 mg in 1 mL | 10 mg/mL | 1.0 mg | 1.75 |
| 10 mg in 2 mL | 5 mg/mL | 0.5 mg | 3.5 |
| 10 mg in 5 mL | 2 mg/mL | 0.2 mg | 8.75 |
| 10 mg in 10 mL | 1 mg/mL | 0.1 mg | 17.5 |
The "1 to 2 mg per spray" figure on vendor pages implies 10 to 20 mg/mL at a 0.1 mL pump, a 10 mg vial in 1 mL or less. A spray delivered into the nose is not the same as a dose absorbed, which is the point of the section above. For the injected route, the same vials in syringe units are on the PT-141 dosage page, and the PT-141 calculator setting works any vial and water volume.
What is not established
No nasal PT-141 product is approved, no published study gives the nasal route's absolute bioavailability, and no trial tested the 1 to 2 mg per-spray figures in circulation. The nasal trials themselves were run at 7.5 to 20 mg and were abandoned by their sponsor over blood pressure and variable uptake. Vyleesi's label adds its own limits, one dose in 24 hours and no more than eight a month, set for the injection. Nothing on this page is a dose or a method; the compound is covered in Medibact's PT-141 guide, and dosing decisions belong with a prescriber.
Sources and dates
Opened 2026-10-10: Palatin Technologies' Form 10-K for the fiscal year ended 2009-06-30 (SEC EDGAR, section "Clinical Trials with Intranasal Formulations"); the abstracts of Diamond et al. 2004 (PMID 14963471), Diamond et al. 2005 (PMID 15833522), Diamond et al. 2006 (PMID 16839319) and Safarinejad 2008 (PMID 18206919, with its 2023 expression of concern); the Edinoff et al. 2022 review full text (PMC8788464) for the 2017 alcohol study's 20 mg dose; ClinicalTrials.gov's bremelanotide records (10, read individually) including NCT00425256; the Vyleesi label via openFDA (version effective 2025-11-13), section 12.3. The label dose and limits are carried from this site's PT-141 page (read 2026-09-18). Ratios and per-spray figures are arithmetic by this site. Corrections go to the contact page.