Sildenafil, the active ingredient in Viagra, a phosphodiesterase-5 inhibitor (PDE5 inhibitor), is not only an erectile dysfunction drug. It is also approved to treat pulmonary artery hypertension, a complication that can worsen the prognosis for patients who have heart failure with preserved ejection fraction (HFpEF), also referred to as diastolic heart failure. Approximately half of people with heart failure have HFpEF.
Researchers from The Wright Center for Graduate Medical Education, Scranton, Pennsylvania, recently conducted a meta-analysis to determine the efficacy of sildenafil specifically on the hemodynamic parameters in patients with HFpEF. They identified only four randomized controlled studies with a total of 379 patients suitable for use for the meta-analysis.
Lead author Anurag Bajaj stated, “The literature evaluating the effect of sildenafil in HFpEF is scant and lacks precision in view of the small patient size.”
After analyzing those available studies they determined that: “Overall, sildenafil did not demonstrate significant improvement in hemodynamic parameters in patients with HFpEF,” MPR reported. “More randomized controlled trials are needed to define the role of sildenafil in HFpEF,” Bajaj concluded.
As this study is suggesting that sildenafil might not be helping certain patients after all, other studies are suggesting that it could be instead harming them. PDE5 inhibitors have been found by researchers of multiple studies to encourage the growth of the most dangerous form of skin cancer, melanoma.
According to the Skin Cancer Foundation, although less than 1 percent of skin cancer cases are melanoma, it causes most skin cancer deaths. An estimated 9,730 people will die of melanoma in 2017.
In 2014 researchers in the U.S. in a 10-year followup study of 25,848 men found an 84 percent increased chance of developing melanoma in men who take sildenafil compared to men who did not. A year later, another population-based study, which included 24,390 men, also found a statistically significant link between these drugs and increased risk for melanoma. Last year, biochemists using human cell cultures and animals showed the mechanism by which the drugs were facilitating melanoma to “grow more vigorously.”
Currently the U.S. Food and Drug Administration (FDA) is looking into the need for regulatory action against all PDE5 inhibitors related to the melanoma risk.