PT-141 nasal spray vs injection: what the studies show

Answer first

PT-141 (bremelanotide) was first developed as a nasal spray for erectile difficulty in men. That programme was abandoned before phase 3. The only approval found, in the United States since 2019, covers an injection under the skin for premenopausal women with low sexual desire. No study comparing the two forms directly could be found.

At a glance

How each form reaches the body

Both forms carry the same molecule. PT-141, international name bremelanotide, is a ring of seven amino-acid building blocks, designed as a copy of the body signal alpha-MSH (alpha-melanocyte-stimulating hormone) ^[1], ^[2]. The form changes how it enters the body.

What both forms share

• The ring resists breakdown. The ring is closed by a bridge between two side chains, and one building block sits in its mirror-image form. Both make the molecule far harder for the body's peptide-splitting enzymes to break down ^[2], ^[3].
• The same receptors. It switches on all five melanocortin receptors, a family of docking points on nerve cells and pigment cells. The label names MC1R and MC4R as the ones that matter ^[1].
• A brain target. MC4R sits mainly in the brain. In animals the substance switched on nerve cells in the hypothalamus, a control centre for arousal, in a region wired to the genital tissue ^[4].
• A skin effect. MC1R drives pigment production, which explains the darker skin patches seen with repeated use ^[1].

Injection under the skin (subcutaneous)

• Almost all of it reaches the blood. The label gives a bioavailability of about 100 per cent after injection under the skin ^[1].
• Peak level after about an hour. The time to peak is about 1.0 hour, with a range of 0.5 to 1.0 hours ^[1].
• Half-life of about 2.7 hours. The range is 1.9 to 4.0 hours ^[1].

Nasal spray (intranasal)

• Measured in the early programme. The first placebo-controlled trials in men recorded blood levels as well as effects ^[5].
• Kinetics of the nasal form. In healthy men given the nasal spray, the median time to peak was 0.50 hours and the mean half-life ranged from 1.85 to 2.09 hours ^[5].
• How much reaches the blood is open. No figure for the share of a nasal dose that reaches the bloodstream could be found in the sources reviewed for this page.

The core difference lies in how much is known. The injected form has a complete label with kinetic data. The nasal form has kinetic figures from the early programme only, and no figure for its uptake through the lining of the nose could be found.

What the studies show

No study comparing the two forms directly could be found in the sources reviewed for this page. The two forms belong to different eras of development. The nasal spray was studied in the early programme, mostly in men ^[5]. The switch to women and to injection came in 2011 to 2012. The injection then carried the programme through to approval ^[2], ^[6].

Nasal spray: erectile response in men

Phase 1 RCT, nasal Placebo-controlled trials enrolled healthy men and men with mild to moderate erectile difficulty. Above a threshold dose level, the erectile response measured by an instrument beat placebo. The first response came after about 30 minutes ^[5].

No maximum tolerated level was established. Flushing and nausea were the commonest complaints ^[5]. The number of participants is not stated in the sources reviewed for this page.

Nasal spray combined with sildenafil

Crossover RCT, nasal A crossover trial in 19 men with erectile difficulty combined sub-threshold levels of the nasal form with sildenafil. Over six hours it measured a larger erectile response than sildenafil alone, with no new side effects ^[7].

The programme was abandoned before phase 3 ^[7]. None of the sources reviewed for this page states the reason for ending it. Men are not covered by the only approval that exists ^[1].

Nasal spray in women with arousal difficulty

Phase 1 RCT, nasal An early crossover trial in 18 premenopausal women with arousal difficulty used the nasal formulation ^[8]. More women reported moderate or high desire after the substance than after placebo (p = 0.0114) ^[8].

Among those who had intercourse within 24 hours, more were satisfied with their arousal (p = 0.0256). The objectively measured vaginal blood flow did not change significantly ^[8].

Nasal spray with alcohol

Phase 1 RCT, nasal A randomised, double-blind crossover trial gave the nasal form, with and without alcohol, to 24 healthy men and women ^[9].

Single doses were generally well tolerated. The trial found no clinically meaningful interaction between the two in how the body handled them. It also found no relevant blood-pressure-lowering or postural effects ^[9].

Injection: the dose-finding trial

Phase 2b RCT, injection This trial gave three dose levels under the skin to 612 women with arousal or desire difficulty. Its main endpoint was the number of satisfying sexual events over four weeks ^[6].

That number rose by 0.2 on placebo and by 0.6, 0.7 and 0.8 at the lowest, middle and highest tested levels. The highest level beat placebo, with p < 0.05 in the registry. That is roughly half an extra event in four weeks ^[6].

Injection: the approval trials

Phase 3 RCT, injection The two RECONNECT trials randomised 1,267 premenopausal women with acquired, generalised low sexual desire that caused them distress. Both ran 24 weeks against placebo ^[1].

Desire was scored on a questionnaire domain from 1.2 to 6.0 points. The gain over placebo was 0.30 points in study 301 and 0.42 in study 302, both at p < 0.001, and 0.35 combined ^[1], ^[10].

Distress, scored from 0 to 4, fell 0.37 points further than on placebo in study 301 and 0.29 points further in study 302. Combined, that was 0.33 points ^[1].

Injection: the outcomes that did not move

Independent re-analysis The number of satisfying sexual events was replaced for phase 3 by the two questionnaire scores. A review of the regulator's files found no additional satisfying event, on average ^[6], ^[11].

Independent re-analysis Dropout because of side effects was far more common than on placebo. The odds ratio was 11.98 (95 per cent confidence interval 3.74 to 38.37), one extra dropout for every six women treated ^[12].

Measured by who finished and chose to continue, the odds favoured placebo at 0.30 (0.24 to 0.38). According to the re-analysis, 72.72 per cent of the endpoints laid down in the trial plans went unreported ^[12].

Injection: the year-long extension

Open-label extension, injection After the core phase, 684 women entered a 52-week extension without a placebo group, and 272 finished it ^[13].

Among women treated throughout, desire rose 1.25 to 1.30 points from baseline. Attrition on that scale limits what the results can carry ^[13].

Why the figures cannot be set side by side

The nasal figures come from small groups, mostly men, over single sessions, and measure erectile response or short-term reports. The injection figures come from hundreds of premenopausal women over 24 weeks and measure questionnaire scores. Populations, amounts, endpoints and durations all differ, so none of these numbers can be weighed against the others.

Safety and side effects

The two forms rest on very different amounts of safety data. The injected form has a label built on two controlled approval trials in 1,267 women. The nasal form has a handful of small early trials.

Nasal spray

• Flushing and nausea. These were the commonest complaints in the early trials in men. No frequencies are given in the sources reviewed for this page ^[5].
• No new side effects with sildenafil. The combination trial in 19 men reported none beyond those of the single substances ^[7].
• Alcohol. Single doses with and without alcohol were generally well tolerated in 24 healthy adults ^[9].
• Vital signs. The first trials in men reported no clinically significant changes in vital signs, laboratory tests or heart tracings ^[5].
• Gaps. No data on irritation of the nose, on repeated use or on separate blood-pressure figures from the male programme could be found in the sources reviewed for this page.

Injection under the skin

• Nausea in 40.0 per cent against 1.3 per cent on placebo. Giving ondansetron beforehand did not reduce it, according to the label ^[1], ^[14].
• Flushing in 20.3 per cent against 0.3 per cent. Headache affected 11.3 per cent against 1.9, and vomiting 4.8 per cent against 0.2 ^[1].
• Reactions at the injection site in 13.2 per cent against 8.4 per cent ^[1].
• A brief rise in blood pressure with a slower pulse. The label gives an average rise of about 6 mmHg systolic and 3 mmHg diastolic, and a fall in pulse of up to 5 beats per minute. Both usually settle within 12 hours ^[1].
• Darker patches of skin. Face, gums and breasts darkened in about 1 per cent under the licensed pattern of use, and in 38 per cent in one investigation with more frequent use. Not every case faded ^[1].
• Serious events. Study 301 recorded 4 of 324 treated women against 1 of 319 on placebo, and no deaths ^[10].

Blood pressure trial, injection A dedicated trial in 397 premenopausal women measured blood pressure over 24 hours. Its publication describes the substance as given under the skin. In the first four hours, systolic pressure rose 3.1 and 3.2 mmHg above placebo at the highest tested level. Peak rises usually lasted under 15 minutes, and 26 women left because of predefined rises ^[15].

The trial's authors wrote that its results led to in-clinic blood pressure monitoring during the larger development trials ^[15].

Contraindication. The label bars the substance outright for anyone with uncontrolled high blood pressure or known cardiovascular disease ^[1], ^[15].

Why this page lists no doses. PT-141 is a prescription-only medicine, and its label ties use to a medical check of heart and blood pressure. European advertising law keeps dosing information for prescription medicines out of material for the general public. Amounts for either form would read as an instruction rather than a citation, so this page names none ^[1].

Legal status

Switching between forms

No study that switched participants from the nasal spray to the injection, or gave both forms together, could be found in the sources reviewed for this page. The move from one form to the other happened between development programmes, with different participants and different questions ^[2], ^[6].

The only combinations on record involve other medicines. In men, the nasal form was combined with sildenafil in one small crossover trial ^[7]. A later trial combines the substance with tirzepatide in obesity and has posted no results ^[16].

The blend directory has one entry that contains PT-141, the PT-141 + Melanotan II combination. It pairs PT-141 with a different melanocortin substance that is approved nowhere, and it names no form. No study of that mixture could be found in the sources reviewed for this page.

Frequently asked questions

Which is better, PT-141 nasal spray or injection?

That cannot be decided from the published record. No study comparing the two forms directly could be found in the sources reviewed for this page. The nasal form was tested in small early trials, mostly in men with erectile difficulty. The injected form was tested in two phase 3 trials in 1,267 premenopausal women, where a desire score rose 0.35 points over placebo.

Is PT-141 nasal spray or injection safer?

No study comparing the safety of the two forms could be found in the sources reviewed for this page. For the injection, the label reports nausea in 40.0 per cent of treated women and a brief rise in blood pressure. For the nasal form, the early trials name flushing and nausea as the commonest complaints, from far fewer participants.

What is the difference between PT-141 nasal spray and injection?

Both contain the same molecule, bremelanotide, which acts on melanocortin receptors. The nasal spray was the form of the early programme in men and was abandoned before phase 3. The injection under the skin is the form of the later trials in women and the only form with an approval, in the United States.

Can PT-141 nasal spray and injection be used together?

No study that gave the two forms together, or switched from one to the other, could be found in the sources reviewed for this page. The only combinations on record involve other medicines: sildenafil with the nasal form in men. The blend directory has one entry with PT-141, which pairs it with Melanotan II.

Is the PT-141 nasal spray approved?

No approval of a nasal form could be found. The only approval found worldwide was granted in the United States on 21 June 2019 under NDA 210557, and it covers the injected autoinjector product. Register checks on 17 September 2026 found no approval in the European Union, Germany, the United Kingdom, Canada or Switzerland. The Australian register could not be reached, so no finding is claimed there ^[17], ^[18], ^[19], ^[20], ^[21].

Why was the PT-141 nasal spray discontinued?

The sources reviewed for this page record that the nasal programme in men was abandoned before phase 3. None of them states a reason, so this page gives none. Development then moved to women and to injection under the skin ^[7], ^[6].

Does PT-141 nasal spray raise blood pressure?

The first nasal trials in men reported no clinically significant changes in vital signs, but no separate blood-pressure figures from them could be found in the sources reviewed for this page. A trial of the nasal form with alcohol found no relevant blood-pressure-lowering or postural effects. The rise in blood pressure with a slower pulse is documented for the injected product, and its label bars use in uncontrolled high blood pressure ^[5], ^[9], ^[1].

How long does PT-141 last as a nasal spray or injection?

After injection under the skin, the half-life is about 2.7 hours and peak levels come after about 1.0 hour. In healthy men given the nasal spray, a median time to peak of 0.50 hours and a mean half-life of 1.85 to 2.09 hours were reported. These figures come from different studies and cannot be compared exactly ^[1], ^[5].

Is PT-141 banned in sport, in either form?

No. A full-text check of the 2026 prohibited list on 17 September 2026 found no entry for bremelanotide or PT-141. The catch-all class S0 does not apply either, because the American approval exists. See peptides banned in sport ^[22].