Oral erectile dysfunction (ED) drugs, which belong to a class of medications called phosphodiesterase 5 (PDE5) inhibitors, are widely used and highly effective but can cause such side effects as headache, upset stomach, nasal congestion, facial flushing and hearing and vision problems. Men who've recently had a heart attack or have severe heart disease have to use oral ED drugs with caution, if at all.
The new cream consists of nanoparticles that can carry drugs or other substances, such as nitric oxide, and deliver them in a controlled and sustained manner, according to the researchers, who are from Albert Einstein College of Medicine at Yeshiva University in New York City. Nitric oxide is the signaling molecule that dilates blood vessels responsible for creating an erection.
The nanoparticle therapy was tested on 18 rats bred to have age-related ED. Some rats received nanoparticles with nitric oxide, others received nanoparticles with nitric oxide plus an experimental ED drug called silorphin (which has a different mechanism of action than PDE5 inhibitors) and a third group of rats received nanoparticles with nitric oxide and the PDE5 inhibitor tadalafil (Cialis).
Five of seven of the rats that received nanoparticles with nitric oxide and all 11 rats that received nanoparticles with nitric oxide and either silorphin or tadalafil showed significant improvements in erectile function.
"The response time to the nanoparticles was very short, just a few minutes, which is basically what people want in an ED medication," study co-author Dr. Joel M. Friedman, a professor of physiology, biophysics and medicine, said in a news release from the university. "In both rats and humans, it can take 30 minutes to one hour for oral ED medications to take effect."
The study appears online Sept. 18 in the Journal of Sexual Medicine.
If safety and dosing studies in rats are successful, human trials of the nanoparticle therapy could begin within a few years, the researchers said.