Editor’s Note: This article was originally published in October 2020. It has been updated for accuracy and clarity to emphasize that PnPP-19 was studied in animal models, not humans. Earlier wording suggesting that the experimental treatment was more effective than or could replace Viagra has been corrected because the research did not establish those conclusions in people. The original publication date and historical context have been preserved.
Phoneutria Nigriventer. Image Courtesy of Techuser
Key Takeaways
- PnPP-19 is a synthetic peptide inspired by a toxin from the Brazilian wandering spider, rather than spider venom being directly applied as a treatment.
- Topical PnPP-19 improved measures of erectile function in diabetic and hypertensive animal models, but its effectiveness in humans had not been established.
- The peptide may offer a different approach from sildenafil, but the study did not prove that it is safer, more effective, or capable of replacing Viagra in people.
A synthetic peptide inspired by a toxin found in the venom of the Brazilian wandering spider (Phoneutria nigriventer) could eventually lead to a new topical treatment for erectile dysfunction, according to research published in The Journal of Sexual Medicine.
The compound, called PnPP-19, improved erectile function when tested in animal models of diabetes and hypertension. However, the research was conducted primarily in rats and mice, so it remains unknown whether the treatment will be safe and effective for men with erectile dysfunction.
From Spider Venom to a Potential Treatment
The venom of Phoneutria nigriventer contains a toxin called PnTx2-6 that has been associated with priapism—an abnormally prolonged erection—in cases of envenomation.
Because the original toxin is highly toxic, researchers developed PnPP-19, a synthetic 19-amino-acid peptide based on molecular modeling of PnTx2-6. The goal was to preserve potentially useful effects on erectile function while avoiding the toxicity associated with the original venom component.
Previous animal experiments suggested that PnPP-19 could improve erectile function without the toxic effects associated with PnTx2-6.
A Topical Gel for Erectile Dysfunction?
In the 2019 study, Brazilian researchers investigated PnPP-19 in hypertensive and diabetic animal models, conditions that are commonly associated with erectile dysfunction.
The peptide improved relaxation of corpus cavernosum tissue from hypertensive rats and diabetic mice and rats. When researchers applied PnPP-19 topically to diabetic rats, measurements of erectile function also improved.
Researchers additionally found that the peptide increased levels of cyclic guanosine monophosphate (cGMP), an important part of the nitric oxide pathway involved in penile smooth-muscle relaxation and erection.
Interestingly, PnPP-19 produced an additive effect when administered with sildenafil, the active ingredient in Viagra. Researchers reported that its mechanism appeared to work independently of phosphodiesterase type 5 (PDE5) inhibition, the mechanism targeted by sildenafil.
Could It Replace Viagra?
It is too early to know.
The results suggest that PnPP-19 could become a candidate for treating erectile dysfunction, including cases associated with diabetes or hypertension. A topical treatment could also offer an alternative approach to oral ED medications.
However, the study did not demonstrate that PnPP-19 is superior to Viagra in humans. The experiments involved animal models and laboratory tissue, and the researchers noted that only about 10% of the topically applied peptide permeated the skin.
Further research, including appropriate human clinical trials, would therefore be required before PnPP-19 could be considered an established treatment for erectile dysfunction.
Final Thoughts
PnPP-19 represents an interesting example of how compounds inspired by animal venoms may lead researchers toward new medicines. The animal results suggest that the peptide deserves further investigation as a potential topical treatment for erectile dysfunction.
However, the findings should not be interpreted as evidence that spider venom gel can replace Viagra. As of the study’s publication, PnPP-19 remained an experimental treatment candidate that required considerably more research before its safety and effectiveness in humans could be established.
Reference
Nunes da Silva, C., Nunes, K. P., De Marco Almeida, F., Silva Costa, F. L., Borges, P. V., Lacativa, P., Pimenta, A. M. C., & de Lima, M. E. (2019). PnPP-19 peptide restores erectile function in hypertensive and diabetic animals through intravenous and topical administration. The Journal of Sexual Medicine, 16(3), 365–374. https://doi.org/10.1016/j.jsxm.2019.01.004