An erection involves the relaxing of a muscle that enables blood to flow into and remain in the penis. Thus, for men whose physical problems are so severe that they do not respond to any type of stimulation, the drug is less likely to be effective. Men who take nitrates for heart disease should not take Viagra because of the risk for hypotension. Some reduction in sexual function is normal with age, but contrary to what many older men and women assume, many declines in sexual performance are treatable. Studies have shown that impotence affects approximately half of men older than 50, with the prevalence increasing in older age groups.
Impotence usually results from a problem with that vascular process.
Dr. Rajfer and other UCLA researchers including Louis Ignarro, M.D., professor of pharmacology, have identified a chemical, nitric oxide, that triggers the erectile process and may become deficient with age. They are currently studying the genes that regulate production of nitric oxide to see whether, ultimately, an effective treatment approach might put more of this chemical into the aging penis. Certain drugs can interfere with sexual function or desire. Often, other drugs can be substituted or an additional medication can be prescribed to reverse the side effect. Another medication, in pill form, is expected to be released later this year.