Nanoparticle-based Erectile Dysfunction Therapy Shows Promise

An innovative drug-delivery system – nanoparticles encapsulating nitric oxide or prescription drugs – shows promise for topical treatment of erectile dysfunction (ED), according to a new study by scientists at Albert Einstein College of Medicine of Yeshiva University.

The new system, tested successfully on a small number of animals, could potentially prevent side effects associated with oral ED medications, if study results can be replicated in humans. That could mean safer and more effective ED therapy for millions of men with heart disease and other health problems affecting erectile function. The study is published today in the online edition of the Journal of Sexual Medicine.

Tens of millions of men worldwide have benefited from oral ED medications such as sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis). However, these medications - which belong to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors - have limitations. They can cause systemic side effects that can be serious. These side effects include headache, facial flushing, nasal congestion, upset stomach, abnormal vision as well as isolated reports of hearing and vision loss. Men who've recently suffered a heart attack or stroke or have severe heart disease should use these drugs with caution or not at all. In addition, "an estimated 30 to 50 percent of men with ED do not respond to oral use of PDE5 inhibitors," says senior author Kelvin P. Davies, Ph.D., associate professor of urology at Einstein.

The drug-delivery system, developed by Einstein scientists, consists of nanoparticles – each smaller than a grain of pollen – that can carry tiny payloads of various drugs or other medically useful substances and release them in a controlled and sustained manner.

The limited number of topical formulations of ED drugs has so far proven ineffective. This study was done to evaluate whether the Einstein nanoparticles, which have been shown to penetrate the skin, might allow the targeted delivery of compounds that treat ED and thereby avoid the drugs' systemic effects.

An effective topical therapy could be especially significant for those ED patients – particularly men with diabetes – who have reduced levels of nitric oxide (NO), the signaling molecule that dilates blood vessels responsible for erectile activity. These men, who often aren't helped by oral PDE5 inhibitor drugs, may benefit from direct application of NO or the PDE5 inhibitors.