The active ingredient in several types of drugs to treat erectile dysfunction (ED) may be protective of heart health, finds a new study from the Karolinska Institutet, examining more than 43,000 male participants for nearly three and a half years.
Phosphodiesterase-5 (PDE-5) inhibitors, also known as the magic behind drugs like Viagra and Cialis, were initially developed to treat angina, a heart condition causing severe chest pain due to a lack of oxygenated blood to the heart. PDE-5 inhibitors are more commonly applauded now for the treatment of ED, but their heart protective qualities have not been forgotten.
Penile erection is a result of smooth muscle in the penis relaxing, a process mediated by a spinal reflex as well as sensory and mental stimuli. A molecular pathway called cGMP produces several compounds that are key players during the penile erection process. Because of the importance of this pathway, drugs treating ED, a lack in penile smooth muscle relaxation, were created to boost cGMP levels. PDE-5 inhibitors prevent PDE-5 from degrading cGMP, elevating cGMP levels and boosting the potential for penile erection.
The new study included men 80 years old or younger being prescribed drugs for ED after their first heart attack. After adjusting for potentially confounding variables like diabetes, heart disease, and stroke, researchers observed several protective effects among the men prescribed ED drugs containing PDE-5 inhibitors.
These men were one-third less likely to die from any cause, and 40 percent less likely to be hospitalized for heart failure. This positive association with ED drugs is specific to PDE-5 inhibitors; there was no such association between men after their first heart attack and a different type of ED drug that works via a different mechanism. ED - in general - is associated with an increased risk of heart disease in otherwise healthy men, a link that led to scientists being surprised by their findings.
Despite the observations made during this study, direct cause and effect between PDE-5 inhibitors and heart health has yet to be clearly demonstrated. Is a prescription for ED simply resulting in a more active sex life which then promotes better heart health? Or are older people who are fit enough to continue with an active sex life more likely to have better heart health?
"If you have an active sex life after a heart attack, it is probably safe to use PDE5 inhibitors," said lead author of the recent study, Daniel Peter Andersson, MD, PhD. "This type of erectile dysfunction treatment is beneficial in terms of prognosis, and having an active sex life seems to be a marker for a decreased risk of death."