Erectile dysfunction is often a sign of a more severe vascular problem that involves abnormalities in the lining of the blood vessels. And often, endothelial dysfunction is an underlying problem for ED - it can be one of the first signs of atherosclerosis, a build-up of plaque and blockages in the arteries.
"It's already known that there is a connection between erectile dysfunction and coronary disease. The risk factors are the same for both, and thus, ED can be a marker for coronary disease," explains lead author Howard Herrmann, MD, Professor of Medicine and Director of the Interventional Cardiology and Cardiac Catheterization Laboratories at the Hospital of the University of Pennsylvania. "Normal erections are caused when nitric oxide is made, but with endothelial dysfunction, the body doesn't make enough of it, causing the erectile dysfunction. Normally, Viagra prevents the breakdown of the little nitric oxide that is there, so that there is enough of it for an erection to occur."
However, about 10-30 % of men are classified as "Viagra non-responders" - in these men, Viagra did not significantly help their erectile dysfunction. So in a small, double blind, randomized, placebo-controlled study at Penn, Herrmann looked at a dozen patients with ED who had not responded well to Viagra. He gave them either a high-dose Lipitor or a placebo. He then rechallenged them with Viagra and asked if the ED had improved.
"There did seem to be some improvement for those who received Lipitor versus the placebo," said Herrmann. "We theorized that if you could make the edothelium healthier through the use of statins -- so that there is more nitric oxide available -- you would improve the endothelial dysfunction and Viagra would work better for the patient."
And there are other potential benefits too. Stan Schwartz, MD, Director of the Diabetes Disease Management program at Penn and co-author, states, "Patients with Diabetes, both Type 1 and Type 2, are plagued with complications of the diabetic state that involve endothelial dysfunction. This research points us in a direction that says any drug class that improves endothelial dysfunction may also be beneficial to patients with diabetes."
Additionally, Emile Mohler, MD, Director of Vascular Medicine at Penn and co-author, cautions, "ED is a sign that cholesterol plaque may be present in the heart, neck or leg arteries. Men with ED should be evaluated for vascular disease."
"These preliminary results show promise," adds Herrmann. "They support the hypothesis that erectile dysfunction may be one sign of a generalized vascular disorder characterized by endothelial dysfunction and that statin drugs may improve the endothelial dysfunction, even before altering the lipid profile. But the results are preliminary and warrant further testing in a larger clinical trial," he cautions.
It should be noted that beyond endothelial dysfunction, there are other reasons Viagra may not work well for someone.
The results of this study were published in the March 2006 issue of the "Journal of Sexual Medicine." Members can access the journal on-line at: http://jsm.issir.org/. The article is titled, "Can Atorvastatin Improve the Response to Sildenafil in Men with Erectile Dysfunction Not Initially Responsive to Sildenafil? Hypothesis and Pilot Trial Results."
This study was supported by an unrestricted medical center grant from Pfizer.
Editor's Notes: Dr. Howard Herrmann has received honorarium from Pfizer and Lilly ICOS. Dr. Stan Schwartz is a consultant and has received a speaker's honoraria from Lilly ICOS. Dr. Emile Mohler is part of the speaker's bureau for Pfizer.
To schedule an interview with Dr. Howard Herrmann (http://pennhealth.com/Wagform/MainPage.aspx?config=provider&P=PP&ID=1211), please contact Susanne Hartman at 215-349-5964 or susanne.hartman@uphs.upenn.edu.
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Journal
The Journal of Sexual Medicine