Titus Thorne

Last Updated September 17, 2022

Titus Thorne

 September 17, 2022

Curious about how PT-141 and Viagra work together? Inside, researchers will find everything they must know about these potent compounds.

A peptide analog of α-Melanocyte-stimulating hormone (α-MSH), PT-141 has been approved as bremelanotide by the United States Food and Drug Administration (FDA) for treating libido issues in women.

Researchers are now studying PT-141 for its potential to treat sexual dysfunction in men, including erectile dysfunction (ED) and low libido.

Stil, the most popular medication today for treating erectile dysfunction is sildenafil. Known more commonly as Viagra, it has been available as a prescription medication in the US for over two decades. It is used to maintain and increase erection strength, namely in older men.

Researchers specializing in male sexual disorders may be curious as to how both PT-141 and Viagra interact with each other. Is it safe to combine PT-141 and Viagra? Is PT-141 better than Viagra in the context of male sexual health?

We have provided extensive information in this guide to answer these questions and more.

Disclaimer: Peptides.org contains information about products that are intended for laboratory and research use only, unless otherwise explicitly stated. This information, including any referenced scientific or clinical research, is made available for educational purposes only. Peptides.org makes every effort to ensure that any information it shares complies with national and international standards for clinical trial information and is committed to the timely disclosure of the design and results of all interventional clinical studies for innovative treatments publicly available or that may be made available. However, research is not considered conclusive. Peptides.org makes no claims that any products referenced can cure, treat or prevent any conditions, including any conditions referenced on its website or in print materials.


What is PT-141?

Also known as bremelanotide, PT-141 is a synthetic melanocortin receptor agonist approved in 2019 by the US FDA for the treatment of generalized hypoactive sexual desire disorder (HSDD) in premenopausal women [1, 2].

Chemically, it is a cyclic hepta-peptide lactam analog of alpha-melanocyte-stimulating hormone (alpha-MSH), and a derivative of the synthetic melanocortin melanotan 2. It acts by binding to receptors of the melanocortin family, namely melanocortin 3 and 4 receptors (MC3-R and MC4-R).

Melanocortins influence a range of biological functions and responses in the human body, including cardiovascular activity, neural activity, inflammation/inflammatory response, and sexual behavior.

Bremelanotide (PT-141) was originally developed by Palatin Technologies and is now available in the United States under the trade name Vyleesi, a prescription-only, self-administered subcutaneous HSDD therapy [3, 4].

The Vyleesi medication guidelines recommend that it be administered one hour prior to sexual activity, once every 72 hours, and not exceeding eight times per month [5].


PT-141 Viagra


Benefits of PT-141

While PT-141 has been approved to treat HSDD in women, the peptide has also been shown to provide a number of benefits for male subjects experiencing sexual dysfunction.

PT-141 improves intercourse satisfaction in subjects with ED

Researchers in a 2008 study looked at how men with erectile dysfunction would respond to PT-141 after displaying a lack of response to Viagra. They intranasally administered 10mg of bremelanotide up to two hours prior to sexual stimulation, or placebo, to over 300 subjects with ED.

The researchers found that the PT-141 group reported significantly greater intercourse satisfaction compared to placebo, with positive outcomes observed in nearly one-third of men administered PT-141. The researchers concluded that PT-141 could serve as an erectile dysfunction alternative to Viagra [6].

PT-141 may improve mood and well-being

Studies have shown that melanocortin peptides have facilitatory effects on dopaminergic neurotransmission. A two-week rodent study showed that intracerebroventricular infusion of melanotan 2, from which PT-141 is derived, induced changes in dopamine D(1)-like receptor binding throughout different parts of the rodents’ brains [7].

The authors suggested that chronic infusion of a melanocortin receptor agonist can influence changes in dopaminergic neurons, and that melanocortin peptides such as PT-141 may regulate the activity of central dopamine neurons, thus leading to a greater sense of well-being [7].

PT-141 stimulates sexual arousal in female subjects with low libido

As discussed, PT-141 is already approved to treat low or lack of libido in premenopausal women. It is well-established the peptide stimulates female sexual desire by activating the melanocortin 4 receptors (MC4R) in the hypothalamus. This process causes the release of dopamine, an excitatory neurotransmitter that leads to increased sexual desire [8].


What is Viagra?

Viagra is the trade name for the drug sildenafil citrate. It is commonly prescribed to improve penile erections in men suffering from ED. It selectively inhibits cGMP-specific phosphodiesterase type 5 (PDE5), which is found in all vascular tissue.

Sildenafil is taken orally or by injection into a vein, taking effect within 20 minutes and lasting up to two hours [9]. It is then broken down in the liver by hepatic metabolism using cytochrome p450 enzymes, mainly CYP450 3A4 (major route), but also by CYP2C9 (minor route) hepatic isoenzymes.

Sildenafil was synthesized in England by a group of pharmaceutical chemists at Pfizer, and was initially studied as a hypertension medication. In phase I clinical trials, researchers found that the drug could induce marked penile erections, which led to it eventually being developed to treat ED. It was patented in 1996 and approved by the FDA in March 1998 [10].

While generally regarded as safe, Viagra has been shown to produce a number of adverse effects. For example, high doses of sildenafil can lead to sudden vision loss in one or both eyes, a potential sign of non-arteritic anterior ischemic optic neuropathy (NAION) [10, 11].

In other rare cases, Viagra may produce an erection for a prolonged period of time (priapism), which can permanently damage the penis. Patients may also experience ringing in their ears (tinnitus), dizziness, or lose hearing [10].

The medication may not be safe for patients with high blood pressure, kidney problems, or a heart condition.


PT-141 Viagra


Benefits of Viagra

Sildenafil has been prescribed to over 23 million men with erectile dysfunction and has earned a reputation as the quintessential ED medication [12].

However, Viagra is known to yield benefits in addition to stimulating erections.

Viagra reduces postejaculatory refractory time

In one study conducted on 60 healthy young men with no reported ED, researchers instructed the participants to take 25mg of sildenafil prior to intercourse. While the researchers did not note any improvements in erection strength, they found that sildenafil caused a significant reduction in postejaculatory refractory time [13].

Viagra can improve quality of sex life

A study conducted on 1956 Chinese males with ED showed that sildenafil significantly facilitated sexual activity, in addition to improving self-confidence, mental status, quality of sexual life, physical vigor, and mental health scores [14].

A similar study on sildenafil found improvements in overall satisfaction with sex life and diminished concerns about erectile problems [15].

Viagra and neurological disorders

Sildenafil has been shown to alleviate damage to the body caused by stroke, subarachnoid hemorrhage, dementia, and neurodegenerative disorders by enhancing angiogenesis and neurogenesis. In addition, sildenafil can cause dilation of nitric oxide pathways, which play a part in the pathogenesis of neurological disease [16].


PT-141 and Viagra | Can They Be Taken Together?

Since PT-141 and Viagra seem to have similar results on male libido and mood, researchers may be interested in observing what their combined effects might be.

One study conducted on nineteen male patients with erectile dysfunction showed specific effects as a result of combining both PT-141 and Viagra. The study involved administering 25mg of sildefanil and 7.5mg of intranasal PT-141, alongside placebos [17].

The study demonstrated that the co-administration of PT-141 and Viagra led to a significantly greater erectile response than administering sildenafil alone. In addition, no adverse effects were observed in any of the study participants [17].

Notwithstanding this study, we remind researchers to exercise caution when considering whether to combine PT-141 and Viagra.


PT-141 Viagra


PT-141 vs. Viagra

PT-141 and Viagra both enhance male arousal and stimulate erections. However, there are some differences in how these two substances act upon the body, as well as their safety profiles and potency.

As far as their respective mechanisms of action:

  • Viagra acts by inhibiting phosphodiesterase 5 (PDE5), an enzyme that promotes the breakdown of cGMP, which regulates blood flow in the penis. Ingestion of sildenafil also results in dilation of the blood vessels in the lungs.
  • By contrast, PT-141 binds to the melanocortin receptors by emulating some attributes of α-MSH. The peptide has highest affinity at MC3R and MC4R, the melanocortin receptors responsible for providing motivation for sex, sexual arousal, and pair bonding [18].
  • Notably, PT-141 stimulates arousal, while Viagra can only produce an erection if sexual arousal is already present. Further unlike Viagra, PT-141 does not act on the vascular system, making the peptide a potentially safer alternative, as it does not affect blood flow and therefore eliminates the possibility of Viagra-associated side effects.

There are have been two notable studies conducted on ED patients who showed a lack of response to Viagra:

  • The earlier cited 2008 study by Safarinejad et al. included over 300 men with ED who did not respond to sildenafil. Over half the group was instructed to intranasally self-administer 10mg of bremelanotide before intercourse, while the rest were given placebo. One-third of the PT-141 group saw positive outcomes, with that group further reporting “significantly greater intercourse satisfaction” compared to the placebo group [6].
  • A 2004 study by Rosen et al. was conducted on both healthy males and ED patients who did not respond to Viagra. The erectile responses induced by PT-141 were statistically significant in both patient groups, and the peptide was deemed safe and well tolerated in both contexts. Notably, the researchers observed a “statistically significant erectile response at [PT-141] doses greater than 1mg” in the healthy male group [19].

Where to Buy PT-141 Online | 2022 Guide

A number of online-only research chemical vendors now sell PT-141 as a reference material.

Unfortunately, a number of these vendors misrepresent their products and source their peptides from overseas, resulting in low-purity formulas.

To help peptide researchers out, our team has made test orders with a number of peptide vendors to evaluate which meet our standards of peptide quality and customer service.

We found that Peptide Sciences is the best source of injectable PT-141 available online. This reputable supplier ships >99% pure PT-141 to researchers around the world.

Here is why we love them:

  • Independent Lab Testing: Peptide Sciences submits each research peptide to rigorous testing via both Mass Spectrometry (MS) and High Performance Liquid Chromatography (HPLC), providing researchers with clear information on the purity of each compound.
  • Competitive Pricing: Researchers may purchase research-grade PT-141 at $49.50 per 10mg vial, with discounts offered for bulk purchases.
  • USA-Made Peptides: Peptide Sciences partners with WHO/GMP and ISO 9001:2008 approved manufacturers to produce research chemicals in line with industry best practices.
  • Fast Shipping: US orders over $200 ship free and arrive within just two to three business days. International orders are often estimated to arrive within seven business days.
  • Superior Customer Care: Researchers may contact Peptide Sciences by email or phone, and their team has a policy of addressing all concerns and inquiries.

Researchers looking to buy high-quality injectable PT-141 for their next study are advised to check out Peptide Sciences, an established leader in the research chemicals industry.

Buy PT-141 from the #1 online Peptides vendor in the world...


Nasal Spray vs. Injectable PT-141

If you have read this far, you are aware that PT-141 may be administered either via injection or as a nasal spray.

The main benefit of intranasal PT-141 administration appears to be related to convenience and portability, as PT-141 nasal sprays are already reconstituted and do not need to be injected. A variety of PT-141 nasal sprays on the market do not even require refrigeration, unlike injectable PT-141 that has already been reconstituted.

Further, a PT-141 nasal spray may produce effects slightly more rapidly, due to the rich network of blood vessels located within the nasal cavities. In a 2004 study, researchers intranasally administered PT-141 at doses greater than 7mg to both healthy males and those with Viagra-responsive erectile dysfunction. Men in both groups achieved erections within 30 minutes of intranasal administration [20].

Researchers wishing to opt for the convenience and portability of a PT-141 nasal spray should visit Pure Rawz.

Their best-selling Arouse spray contains 5mg PT-141 and 5mg Oxytocin, which in animal studies has also been shown to induce erections [21].


Viagra and PT-141 | Verdict

Both Viagra and PT-141 have both been shown to address symptoms of male sexual dysfunction, yet there are notable differences between the two.

Viagra is a PDE5 inhibitor and therefore a vasodilator, while PT-141 is a melanocortin receptor agonist. These compounds are also administered differently, with Viagra being available in tablet form, while PT-141 is administered as either an injectable solution or nasal spray.

Notably, several comparative studies have shown that PT-141 is able to produce effects on male sexual arousal in cases where Viagra treatment has failed.

Researchers interested in further exploring the potential upside of PT-141 should check out Peptide Sciences for injectable PT-141 or Pure Rawz for a quality nasal spray.


References

  1.  Dhillon S, Keam SJ. Bremelanotide: First Approval. Drugs. 2019 Sep;79(14):1599-1606. doi: 10.1007/s40265-019-01187-w. PMID: 31429064.
  2. Commissioner, O. of the. (n.d.). FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women. U.S. Food and Drug Administration. Retrieved August 28, 2022, from https://www.fda.gov/news-events/press-announcements/fda-approves-new-treatment-hypoactive-sexual-desire-disorder-premenopausal-women
  3. Mayer D, Lynch SE. Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder. Ann Pharmacother. 2020 Jul;54(7):684-690. doi: 10.1177/1060028019899152. Epub 2020 Jan 1. PMID: 31893927.
  4. Bremelanotide (Vyleesi) for hypoactive sexual desire disorder. Med Lett Drugs Ther. 2019 Jul 29;61(1577):114-116. PMID: 31381550.
  5. Walid. (2019, August 16). About Vyleesi: Approved bremelanotide injection for HSDD. Vyleesi (bremelanotide injection) 1.75mg/0.3 ml | for subcutaneous use only. Retrieved August 22, 2022, from https://www.vyleesi.com/about-vyleesi/
  6. Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. J Urol. 2008 Mar;179(3):1066-71. doi: 10.1016/j.juro.2007.10.063. Epub 2008 Jan 18. PMID: 18206919.
  7. Lindblom J, Kask A, Hägg E, Härmark L, Bergström L, Wikberg J. Chronic infusion of a melanocortin receptor agonist modulates dopamine receptor binding in the rat brain. Pharmacol Res. 2002 Feb;45(2):119-24. doi: 10.1006/phrs.2001.0913. PMID: 11846623.
  8. Pfaus JG, Sadiq A, Spana C, Clayton AH. The neurobiology of bremelanotide for the treatment of hypoactive sexual desire disorder in premenopausal women. CNS Spectr. 2022 Jun;27(3):281-289. doi: 10.1017/S109285292100002X. Epub 2021 Jan 18. PMID: 33455598.
  9. Sildenafil monograph for professionals. Drugs.com. (n.d.). Retrieved August 22, 2022, from https://www.drugs.com/monograph/sildenafil.html
  10. Boolell M, Allen MJ, Ballard SA, Gepi-Attee S, Muirhead GJ, Naylor AM, Osterloh IH, Gingell C. Sildenafil: an orally active type 5 cyclic GMP-specific phosphodiesterase inhibitor for the treatment of penile erectile dysfunction. Int J Impot Res. 1996 Jun;8(2):47-52. PMID: 8858389.
  11. Laties, A. M., & Zrenner, E. (2002, August 28). Viagra® (sildenafil citrate) and ophthalmology. Progress in Retinal and Eye Research. Retrieved August 20, 2022, from https://www.sciencedirect.com/science/article/abs/pii/S1350946202000137
  12. Jackson G, Gillies H, Osterloh I. Past, present, and future: a 7-year update of Viagra (sildenafil citrate). Int J Clin Pract. 2005 Jun;59(6):680-91. doi: 10.1111/j.1368-5031.2005.00578.x. PMID: 15924597.
  13. Mondaini, N., Ponchietti, R., Muir, G. et al. Sildenafil does not improve sexual function in men without erectile dysfunction but does reduce the postorgasmic refractory time. Int J Impot Res 15, 225–228 (2003). https://doi.org/10.1038/sj.ijir.3901005
  14. Tang WH, Zhuang XJ, Ma LL, Hong K, Zhao LM, Liu DF, Mao JM, Zhang HL, Jiang H. Effect of sildenafil on erectile dysfunction and improvement in the quality of sexual life in China: a multi-center study. Int J Clin Exp Med. 2015 Jul 15;8(7):11539-43. PMID: 26379977; PMCID: PMC4565360.
  15. Hultling C, Giuliano F, Quirk F, Peña B, Mishra A, Smith MD. Quality of life in patients with spinal cord injury receiving Viagra (sildenafil citrate) for the treatment of erectile dysfunction. Spinal Cord. 2000 Jun;38(6):363-70. doi: 10.1038/sj.sc.3101011. PMID: 10889565.
  16. Farooq MU, Naravetla B, Moore PW, Majid A, Gupta R, Kassab MY. Role of sildenafil in neurological disorders. Clin Neuropharmacol. 2008 Nov-Dec;31(6):353-62. doi: 10.1097/WNF.0b013e31815cd94c. PMID: 19050413.
  17. Diamond LE, Earle DC, Garcia WD, Spana C. Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response. Urology. 2005 Apr;65(4):755-9. doi: 10.1016/j.urology.2004.10.060. PMID: 15833522.
  18. Wessells H, Blevins JE, Vanderah TW. Melanocortinergic control of penile erection. Peptides. 2005 Oct;26(10):1972-7. doi: 10.1016/j.peptides.2004.11.035. PMID: 15992962; PMCID: PMC4768007.
  19. Rosen RC, Diamond LE, Earle DC, Shadiack AM, Molinoff PB. Evaluation of the safety, pharmacokinetics and pharmacodynamic effects of subcutaneously administered PT-141, a melanocortin receptor agonist, in healthy male subjects and in patients with an inadequate response to Viagra. Int J Impot Res. 2004 Apr;16(2):135-42. doi: 10.1038/sj.ijir.3901200. PMID: 14999221.
  20. Diamond, L., Earle, D., Rosen, R. et al. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. Int J Impot Res 16, 51–59 (2004). https://doi.org/10.1038/sj.ijir.3901139.
  21. Hemlata Thackare, Helen D. Nicholson, Kate Whittington, Oxytocin—its role in male reproduction and new potential therapeutic uses, Human Reproduction Update, Volume 12, Issue 4, July/August 2006, Pages 437–448, https://doi.org/10.1093/humupd/dmk002.

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