PT-141, which is also known as bremelanotide, is a synthetic heptapeptide and a derivative of Melanotan 2. Its mechanism of action is unique among all other compounds that have been looked at for sexual function since it acts in the central nervous system rather than affecting smooth muscles or blood vessels in the body.
PT-141 is a melanocortin receptor agonist that primarily targets MC4R and also acts on MC3R. Both receptors are found in hypothalamic nuclei responsible for motivational and autonomic control. PT-141 activates the MC4R in the paraventricular nucleus of the hypothalamus, initiating dopaminergic signaling that scientists link to the pro-erectile and pro-desire outcomes. Phase 2 data in men confirmed dose-dependent erectile activity via this central nervous system pathway , without any recorded vascular effects.
That distinction is relevant in practice. PDE5 inhibitors function by relying on nitric oxide to act in the peripheral circulation while PT-141 does not require nitric oxide. Early studies indicate that this drug can trigger a response despite any issues involving vascular signaling, which makes it of interest in those situations when PDE5 inhibitors fail.
The medications sildenafil, tadalafil and those of their class are capable of obstructing PDE-5 enzyme which breaks down cGMP within the smooth muscles in the penis thus enhancing a previously generated nitric oxide signal. These medications are said to be permissive as they cannot exert their actions without sexual arousal as well as having proper conditions in terms of vascular function. The drug PT-141 acts also differently - it targets the central nervous system instead of working at the periphery and provides effect at the level of motivation and arousal before the signal is transmitted.
What the researchers can learn from this study: PT-141 is being tested on people with a very specific definition of the problem. This is why the FDA recognizes it as a treatment for hypoactive sexual desire disorder, but not for erectile dysfunction, and for the same reason the treatment has been approved for women suffering from HSDD but not for men receiving the nasal spray.
Bremelanotide has a plasma half-life of about 2.7 hours. The period of time from subcutaneous injection until the effect kicks in according to some research protocols is 30–60 minutes after injection. Vyleesi prescribing label recommends administering the medication 45 minutes prior to any activity. The time frame reported in studies is 6-12 hours, though some participants said that they experienced the effect for 24-72 hours, which is still not more than the half-life time for the drug.
The existing published evidence for PT-141 can be separated by sex neatly: there is data from phase 3 trials about women who suffer from HSDD, while the evidence for men does not go beyond phase 2 trials. One should note that the distinction is the only honest way to summarize the literature on the subject.
The most transparent data about men comes from the 2003 phase 2 study with healthy volunteers and people with erectile dysfunction who were given PT-141 through the nasal cavity. Researchers recorded a rapid, dose-dependent increase in erectile activity attributable to central nervous system action , but not peripheral vascular effects. The findings from this study represented the basic proof of a concept that helped further developments. Another separate phase 2 program ran on men with subcutaneous injections. However, neither program was further developed and both did not reach phase 3 trials. The nasal program also stopped developing because of increased blood pressure (as explained in the nasal spray summary below). Today, references about treatment effects in men are based on this older phase 2 study, while no similar phase 3 efficacy or safety programs have been conducted yet.
Both studies accomplished their primary goals: a significant improvement in the desire component of the Female Sexual Function Index and a decrease in the level of distress per the Female Sexual Distress Scale-Desire/Arousal/Orgasm compared to the placebo. The results of these two studies led to the FDA approval in June 2019.
A piece of information from the trials that is not usually seen in secondary sources is that the improvement was made as required and not through a daily dose. The women in the trials consumed a single dose of 1.75 mg prior to any expected activity. Nevertheless, the overall benefit after 24 weeks remained statistically significant. This approach with as-required methodology is unique in HSDD pharmacology, and it comes directly from the underlying mechanism.
| Population | Trial Phase | Primary Endpoint Met | Approved Indication | Route Studied |
|---|---|---|---|---|
| Premenopausal Women (HSDD) | Phase 3 (RECONNECT x2). | Yes - desire score and distress score. | Yes - Vyleesi 1.75 mg SC. | Subcutaneous. |
| Men (erectile dysfunction) | Phase 2 only. | Yes - dose-dependent erectile response. | No. | Intranasal, subcutaneous. |
| Men (desire/HSDD) | No controlled trials. | N/A. | No. | N/A. |
The difference is clear. Females have complete regulatory records. Males possess mechanisms proof of concept and data on phase 2 dose-response. Therefore, any study protocol in males relies on earlier and limited evidence.
PT-141 has no impact on testosterone levels. Studies have shown that it affects neither LH, FSH, nor any gonadal hormones. Thus, it cannot be connected with fertility purposes. Additionally, PT-141 does not promote tanning since tanning occurs because of MC1R agonism in melanocytes, while PT-141 has receptors that predominantly work on MC4R and MC3R receptors. There is evidence of darkening of certain areas of the skin following PT-141 application (which can be found in side effects), but that can be regarded as a negative effect, not as a tanning process. Scientists studying melanocortin compounds and searching for the one suitable for achieving pigmentation use other substances.
The dosage references in the following paragraphs are obtained either from the Vyleesi prescription label or from actual clinical trial protocols. They represent the dosages that were utilized during the research and the clinical trials. This website serves as a source for your research, and none of its contents can be used as personal dosage instructions. You can access the complete interactive references by clicking on the peptide dosage calculator and PT-141 dosage guide .
| Dose (mg) | Source / Context | Route | Notes |
|---|---|---|---|
| 0.5 mg | Phase 2 low-dose arm. | Subcutaneous. | Minimal response in early dose-escalation; used as starting reference. |
| 1.0 mg | Phase 2 mid-dose arm. | Subcutaneous. | Intermediate dose-response signal in men. |
| 1.75 mg | Vyleesi approved label dose. | Subcutaneous. | Clinical benchmark; the only dose with a full phase 3 package (women). |
| 2.0 mg | Phase 2 high-dose arm (men). | Subcutaneous. | Higher side-effect frequency at this dose in men; not the approved dose. |
| Dose (mg) | Source / Context | Route | Frequency Limit |
|---|---|---|---|
| 1.75 mg | Vyleesi FDA-approved label. | Subcutaneous autoinjector. | No more than 1 dose per 24 hours; no more than 8 doses per month. |
| 0.75 mg | RECONNECT low-dose exploratory arm. | Subcutaneous. | Lower efficacy signal; not the approved dose. |
After being dissolved in 2 mL of bacteriostatic water, the 10 mg vial of PT-141 has a concentration of 5 mg/mL (5,000 mcg/mL). The table below shows how clinical doses relate to injection volumes at this concentration.
| Dose (mg) | Concentration (5 mg/mL) | Volume to Draw | Insulin Syringe Units (U-100) |
|---|---|---|---|
| 0.5 mg | 5 mg/mL. | 0.10 mL. | 10 units. |
| 1.0 mg | 5 mg/mL. | 0.20 mL. | 20 units. |
| 1.75 mg | 5 mg/mL. | 0.35 mL. | 35 units. |
| 2.0 mg | 5 mg/mL. | 0.40 mL. | 40 units. |
When brought back to its original state using a volume of 1 mL (10 mg/mL), the amounts of all items are reduced by 50%. In case more than one milliliter is used for reconstitution, the volumes have to be multiplied by 1.5.
According to the Vyleesi prescribing information guideline, the administration must be done at least 45 minutes before the expected sexual action. The research processes during the phase 2men's studies also specified the window of administration 45 minutes to 2 hours before sex. Another thing to mention is the availability of hard limits, such as one dose every 24 hours and no more than 8 doses per calendar month. The limits were established based on the data regarding blood pressure and hyperpigmentation, not on common practices.
Lyophilized PT-141 powder remains stable when kept cool, dry, and away from light until it is reconstituted. After the reconstitution, the product should be stored in line with manufacturer instructions within the 2 to 8°C range (appropriate refrigerator temperature range). The normal amount of water needed is between 1 and 3 milliliters of bacteriostatic vial for each 10-milligram vial, and the amount of water determines the final concentration in accordance with the data provided in the table above. It is recommended to add the water into the vial along the side and swirl it gently rather than shaking it.
Researchers frequently ask us: The most prevalent reconstitution mistake is not the amount of water used, but rather removing the syringe before the powder has completely dissolved in the solution. Wait for about 2-3 minutes after mixing the solution.
For a reference that will help you calculate volume per dose based on vial size and reconstitution volume, go to Get US Peptides peptide dosage calculator . This document covers PT-141 and 39 other compounds found in the database.
There are three types of delivery methods, including subcutaneous injection, nasal spray, and oral/sublingual. These delivery forms are proven different as to their bioavailability and treatment records.
All randomized studies that generated effectiveness figures, such as the phase III studies and the phase II studies carried out in men, employed subcutaneous injection. This method of administration avoids the effect of first-pass metabolism and provides predictable plasma levels, which is why it was chosen for the use of the Vyleesi autoinjector. This was the only method for which complete clinical data were available. The standard format for research on subcutaneous administration is 10 mg lyophilized powder vial.
The use of nasal spray for PT-141 in men started in the early 2000s and generated mechanistic data mentioned above. However, it stopped before phase 3 of the trial, as the intranasal delivery caused clinically significant blood pressure spikes at doses required for effectiveness. The blood pressure response was more intense and vaccine unpredictable via nasal route compared to subcutaneous administration so risk-benefit ratio was negative for submission to regulatory body. That is why the nasal program for men has been discontinued: a safety issue of blood pressure for FDA approval is the reason, not lack of efficacy.
The nasal spray PT-141 remains available in research format. The price of the spray is $110.00 and can only be used for research purposes. The nasal route is said to be quicker. However, it has lower and more variable bioavailability. The research team must also note that there is no phase 3 safety package for this mode of administration.
To date, there has been no published data available on the bioavailability of oral or sublingual bremelanotide. Cyclic peptides such as bremelanotide are subjected to degradation by enzymes of the gastrointestinal tract prior to being absorbed. No pharmaceutical company has taken any oral formulations of PT-141 to the next clinical trial stage. Products labelled as “PT-141 tablet” or “oral bremelanotide” can be found on market but there are no studies proving their bioavailability. The oral or sublingual absorption of peptides of this specific molecular weight has not been present in any studies.
| Form | Bioavailability | Onset | Typical Research Dose | Side-Effect Profile |
|---|---|---|---|---|
| Subcutaneous Injection | High (direct systemic). | 30-60 min. | 1.75 mg (label); 0.5-2.0 mg (research). | Nausea, flushing, headache, BP rise. |
| Nasal Spray | Lower, variable. | Faster absorption kinetics. | No established research dose post-discontinuation. | Larger BP signal; nasal irritation. |
| Oral / Sublingual / Pill | Not established. | N/A. | N/A. | Unknown; GI degradation likely. |
The most commonly reported side effect is nausea, which was reported by about 40% of women in the bremelanotide group. There is a high discrepancy in the placebo group. Flushing and headaches occurred in more than 10% of cases in both studies. These three side effects were the most notable tolerability issues in the FDA reviews. The nausea occurs within 30-60 minutes after injection and resolves in a few hours. Some of the participants took antiemetics before treatment during the trials, even though it was not part of the protocol.
The RECONNECT trial publications report nausea in approximately 40% of bremelanotide-treated women, flushing in about 20%, and headache in about 11% , with all three events happening more frequently than in the placebo group. Reports of injection-site bruising as well as soreness were in line with findings following any subcutaneous injections. 17.4% of the subjects in the group taking bremelanotide had to withdraw from their participation in the study, compared to 2.2% withdrawal rate in the placebo group. Nausea turned out to be the main reason for withdrawal from the study.
According to phase 2 male participants, there was a short-lived elevation in blood pressure after subcutaneous and the nasal administration of the drug. This increase in blood pressure was instrumental in terminating the nasal study. Given the similarities in the results obtained, males also reported nausea and flushing after subcutaneous administration, although there is no centralized clinical study involving both sexes. The links also noted a transient increase in blood pressure after each dose regardless of gender.
Focal hyperpigmentation, or darkening of the face, gums as well as breasts has been reported in relation with the consecutive use of bremelanotide medication. This is due to the minuscule activity of MC1R and happens when there is the cumulative administration of the particular medication. The Vyleesi label warns against this known risk of repeated administration, which is largely the reason for the 8-doses-in-a-month limit.
Uncontrolled hypertension and recognized cardiovascular disease are the contraindications present on the label. They are not prohibitions, but rather absolute contraindications included in the medication approved. All the clinical research protocols should recognize these as strict exclusion measures due to blood pressure surges that accompany every dose.
The FDA has provided approval for bremelanotide but its approval is confined to certain criteria.The FDA approved bremelanotide in June 2019 as Vyleesi, a 1.75 mg subcutaneous autoinjector, for acquired, generalized hypoactive sexual desire disorder in premenopausal women . The approved indication pertains to one specific indication, one demographic and one dosage. In addition, it does not include men. No approval has been given for postmenopausal women as well. The method of administration in patients by nasal spray has also not been approved. The use of research vials remains out of the FDA approval too.
According to research data from 2026, both PT-141 nasal sprays and vials sold by chemical suppliers are not approved by the FDA for sale. They are sold under a different regulation that allows only for research purposes. A researcher who buys a 10 mg lyophilized vial will not be purchasing Vyleesi. Even though the entire composition is the same, the regulatory status, the manufacturing process and the use of the compound is different from Vyleesi.
Vyleesi is a drug that requires a prescription and is sold by pharmacies that are allowed to do so according to the rules set by the FDA, following cGMP, with a specified use. It is also possible for 503A compounding pharmacies to prepare bremelanotide for patients with valid prescriptions, in accordance with state pharmacy regulations. Both options differ from obtaining bremelanotide from a research chemical vendor.
Chemical suppliers provide research PT-141 vials - specifically, US Peptide Labs calls itself - a chemical supplier, not a 503A or 503B pharmacy - for laboratory research purposes. The substance, according to the supplier's intentions, is not intended for use in humans. Researchers, organizations and laboratories purchase it under that condition. The Certificate of Analysis provided by a third party (AxisPharm for US Peptide Labs) is proof only of the purity and identity of the substance but not its suitability for the clinical application for a given individual.
In 2026, bremelanotide is not considered a controlled substance by the DEA in the United States. Since it is sold under the brand name Vyleesi, bremelanotide is classified as a prescription drug. However, the research peptide version, sold through chemical suppliers, is categorized differently. While ordering the research peptide PT-141 from a local supplier for legitimate lab research is not against federal law, the purpose of use legally matters.
The compliance with WADA is an issue among competitive sportsmen. PT-141 falls under none of the peptides, hormones, growth factors, melanocortin receptor agonists, or any other group. All athletes who are subject to the anti-doping rule should consult their sporting federation since the national federations have the right to introduce new substances at their discretion in addition to the WADA list; however, according to the 2025 list, PT-141 has not been banned.
Age limit: US Peptide Labs mandates that buyers must be of age 21 or older. This is a store policy rather than a federal mandate on research chemicals. This rule applies to each item purchased from US Peptide Labs.
We routinely monitor the marketplace for research peptides, and the difference in the quality of products for various vendors is higher than what most researchers believe. The main factors influencing this difference are the method of purification verification, trade lot tracking and the question whether the certificate of analysis was issued by an external laboratory or it is an internal analysis. Internal claims about purity cannot be verified.
The US Peptide Labs PT-141 10 mg lyophilized powder is priced at $55.00 sells for $52.25 for 2+ vials, while prices drop to $49.50 for 5 or more vials. The price of one bottle of the PT-141 Nasal Spray is $110.00. While the price of the PT-141 / Oxytocin Nasal Spray blend is $128.00. Free shipping applies to orders above $70 in the US. Ships from the US with tracking attached to each order.
A COA (Certificate of Analysis) that relates to research peptide should include the confirmation of compound identity (by the help of HPLC or mass spectrometry), purity level (% of purity should not be less than 99%), lot number, and the name of the laboratory that conducted the tests including its accreditation. US Peptide Labs has COAs for PT-141 from the laboratory AxisPharm, an independent analytical laboratory and has three lots available. The lot number is indicated on an ampule, so it is possible to check that ampule matches with the COA. This literally means that the phrase "99% laboratory tested" does not have only a marketing sense, since the lot number can be verified.
In order to fully understand the definition of each entry in peptide COA, the document at Get US Peptides COA reading guide provides detailed explanations on how to conduct an analysis of identity, purity, and evaluate third-party certificates.
| Product | Size | Price (US Peptide Labs) | Bulk Price |
|---|---|---|---|
| PT-141 Lyophilized Powder | 10 mg vial. | $55.00. | $52.25 (2+), $49.50 (5+). |
| PT-141 Nasal Spray | Standard spray bottle. | $110.00. | Contact store. |
| PT-141 / Oxytocin Nasal Spray | Blend spray bottle. | $128.00. | Contact store. |
The market pricing for PT-141 research vials varies significantly from vendor to vendor. If the price is below $40 for a 10 mg vial without a third-party certified COA, this should lead a buyer to question how and at what cost the synthesis and purity verification of PT-141 was performed. US Peptide Labs produces the compound in the USA; therefore, if the product was produced domestically and independently tested, this comes at a price and the price reflects the cost of these services.
PT-141 occupies a particular location in the melanocortin family. Knowing how it is distinct from other compounds helps understand how it can be used in research and why it is delivered in combination formats.
Melanotan 2 (MT-II) is the basic compound that has given rise to PT-141, a metabolite of the original substance. It also should be mentioned that MT-II acts as a non-selective melanocortin agonist that acts on MC1R, MC3R, MC4R, and MC5R. When MC1R is activated in melanocytes, tanning is observed. In comparison with MT-II, PT-141 has lower MC1R activity, which makes it reach its goals through the activation of MC4R and not producing pigment. The difference in receptor selectivity is the very reason for the separation between PT-141 and other compounds.
| Compound | Primary Receptors | Tanning Effect | Sexual Function Effect | Clinical Status |
|---|---|---|---|---|
| Melanotan 2 | MC1R, MC3R, MC4R, MC5R. | Yes (MC1R). | Yes (MC4R). | No FDA approval; research only. |
| PT-141 (Bremelanotide) | MC4R (primary), MC3R. | Minimal (low MC1R activity). | Yes (MC4R, primary effect). | FDA approved as Vyleesi (women); research for men. |
Melanotan II 10 mg is available at US Peptide Labs at $55.00 . The full compound profile is in the Get US Peptides Melanotan 2 library entry .
The mechanism of action of kisspeptin is entirely distinct from that of PT-141. Kisspeptin activates the GPR54 (KISS1R) receptors in the hypothalamus, resulting in the induction of GnRH pulses and stimulation of the release of LH and FSH and the processes of gonadal hormone synthesis. Kisspeptin's interest in sexuality is focused on hormones and reproduction but not on the desire. In contrast, PT-141 does not act on the HPG axis. Kisspeptin does not affect melanocortin receptors either. The two subject matters are not the same too: kisspeptin is studied for its hormonal cascade, whereas PT-141 is investigated for desire and arousal processes.
Oxytocin binds to the oxytocin receptors (OXTR) in the brainstem and central nervous system and in the peripheral tissues. Its involvement has been linked to social bonding, recognition, and the release of other hormones following orgasm. The substance does not stimulate the melanocortin receptors. The two compounds, being combined in the nasal form, have different targets in the sexual response, with the first compound acting on the sexual desire and the second one eliciting the feelings of closeness. The PT-141 / Oxytocin Nasal Spray blend is $128.00 which presents a research format on the subject of the combination. The Get US Peptides combination protocols page explains the detailed rationale behind the combination of the compounds. A stand-alone Oxytocin Nasal Spray is also available at $110.00. The oxytocin library entry provides a description of the pharmacology of the receptors.
Apomorphine is known to be a dopamine receptor agonist (acting on D1/D2 types) that has been investigated for treating erectile dysfunction using sublingual delivery route. Apomorphine exerts its effect through the dopaminergic pathways in paraventricular nucleus, which anatomical area also partially coincides with the action site of PT-141 at the MC4R. Nevertheless, the interest in the studies of apomorphine’s effect on sexual function was abandoned in the USA because of very narrow therapeutic window and major nausea when effective doses were used. The use of PT-141 also causes nausea, but the mechanism of its action is somewhat different.
| Compound | Receptor | Primary Research Use | Route | Typical Research Dose |
|---|---|---|---|---|
| PT-141 (Bremelanotide) | MC4R, MC3R. | Sexual desire, arousal, erectile response. | Subcutaneous. | 1.75 mg (label); 0.5-2.0 mg (research). |
| Melanotan 2 | MC1R, MC3R, MC4R, MC5R. | Pigmentation, sexual function. | Subcutaneous. | 0.5-1.0 mg (research). |
| Kisspeptin | GPR54 (KISS1R). | HPG axis, reproductive function. | Subcutaneous, IV (research). | Variable by protocol. |
| Oxytocin | OXTR. | Social bonding, orgasm-related signaling. | Intranasal, IV (research). | Variable by protocol. |
| Apomorphine | D1/D2 dopamine. | Erectile dysfunction (largely discontinued). | Sublingual. | 2-4 mg (historical). |
PT-141 (bremelanotide) acts as a melanocortin receptor agonist that is extensively studied on the impacts of sexual arousal and desire on the central nervous system via MC4R stimulation. In its prescription form known as Vyleesi, it is approved by the FDA for use as a treatment of the condition in premenopausal women known as acquired generalized hypoactive sexual desire disorder. The research syringes and nasal sprays are those that are only for laboratory research purposes. The complete compound profile can be found in the Get US Peptides PT-141 peptide library entry.
Vyleesi ideally should be administered at least 45 minutes before the anticipated activity since it acts in the body within 30-60 minutes after subcutaneous injection. The half-life is estimated to be around 2.7 hours in plasma. The duration of effect has been reported as 6-12 hours in clinical trials although some anecdotal reports suggest the effect lasts longer. The maximum blood pressure occurs at 12 minutes post-injection while the return to baseline levels is noted within 12 hours.
During phase 2 studies, subjects received subcutaneous doses from 0.5 mg to 2.0 mg. The dose 1.75 mg is the Vyleesi label dose, which is used in the studies conducted on women and is the most commonly-used dose in the studies performed on men for comparison. There is no specific approved dose for men; all dosages have been derived from the results obtained from the phase 2 studies. Refer to the PT-141 dosage reference page for complete protocol details.
The approved dosage of FDA for pre-menopausal women suffering from HSDD is by 1.75 mg subcutaneously. It is given at least 45 minutes before sexual activity and not more than once a day and up to maximum of eight times in a month. This is the only dosage having complete phase 3 study and vivacity record. It was seen that smaller dosages (0.75 mg) conducted in exploratory arms had lesser efficiency.
The results of phase 2 testing of nasal spray product in males showed that the amount of substance administered was proportional to degree of erection as a sign of the achievement of action in CNS after nasal administration. The nasal study has been stopped before phase 3 due to the increase in blood pressure of unexpected amount compared to injection way of administration. There is no information on phase 3 safety and efficacy of nasal PT-141. Nasal sprays researches exist but no clinical data are available. Bioavailability of nasal delivery is lower and much more variable than in subcutaneous injection.
Yes, but in a very narrow way. Bremelanotide was approved by the FDA in June 2019 under the name Vyleesi (1.75 mg subcutaneous autoinjector) for the treatment of generalized acquired HSDD in premenopausal women. However, this approval is restricted to women only and does not include men, and the use of nasal spray or for postmenopausal women in addition to research vials.
Yes, a prescription is necessary in order to get Vyleesi (the medicine approved by FDA). PT-141 vials and nasal sprays tempting offers by chemical suppliers such as US Peptide Labs are not medicines; they are produced only for research purposes (for adults aged over 21) and cannot be taken at home for treatment.
PT-141 is a derivative of Melanotan 2 having reduced activity of MC1R. Melanotan 2 activates MC1R, MC3R, MC4R, and MC5R; while PT-141 acts almost exclusively on MC4R and MC3R receptors. What is the practical difference? Melanotan 2 stimulates tanning via MC1R signal in melanocytic cells, and PT-141 does not induce tanning. Hence, both compounds act on MC4R, which is the receptor responsible for central sexual effects. PT-141 was specifically synthesized to preserve MC4R characteristics without increasing skin pigmentation.
According to American researchers, the major criteria are as follows: Domestic production, independent third-party certificate of analysis (not performed by the manufacturer), lot number tracking and clear indications that the product is intended for research use only. US Peptide Labs PT-141 10 mg meets all of those criteria- produced in US labs, verified to contain over 99% purity by AxisPharm, lot number printed on the bottom of the vial, priced at $55.00 per vial with free shipping on orders above $70. The performance and vitality collection and nasal spray collection include similar compounds for comparison purposes.
Browse PT-141 at US Peptide Labs - 99%+ Purity, AxisPharm COA, Free US Shipping Over $70