VIAGARA

Viagra (sildenafil citrate) was introduced by Pfizer in 1998, and it has become one of the most widely recognized brand-name medications on the market in the United States—used by millions of men to treat impotence and sexual erectile dysfunction (“ED”).

Viagra is a phosphodiesterase 5A (PDE5A) inhibitor, which plays an essential role in vascular smooth muscle contraction in the corpus cavernosa (the pair of sponge-like regions of erectile tissue that contain most of the blood in the penis during an erection). PDE5A inhibitors hinder the hydrolysis of cGMP, thereby leading to a smooth muscle relaxation and penile erection.

Since its approval in 1998, Viagra has been prescribed to an estimated 35 million men, and is generally considered safe by most consumers. In addition, the drug brings in roughly $1.7 billion annually. However, recent studies suggest that the medication may reduce the body’s ability to resist the spread of melanoma. 

According to the American Cancer Society, melanoma is diagnosed in about 69,000 Americans each year and causes about 8,650 deaths annually. The skin cancer usually manifests as unusual moles or patches of skin. While it is often curable if caught early, once melanoma has spread beyond the skin and local lymph nodes, treatment is difficult and it may ultimately result in death.

As early as 2011, a U.K. study was published in the medical journal Cancer Cell warned that PDE5A inhibitor drugs could “stimulate a dramatic increase in melanoma cell invasion.” The study further provided that the medications may cause an increase in short-term and long-term colonization of the lungs by melanoma cells.

In 2012, another study published in the Journal of Cell Biochemistry by Chinese researchers specifically cautioned that PDE5A inhibitors could increase cellular cyclic guanosine monophosphate (cGMP) levels, which is linked to increased melanoma risk by a process known as melanin synthesis.

In April 2014, Harvard Researchers published a study in the medical journal JAMA Internal Medicine, indicated that users may be 84% more likely to be diagnosed with melanoma. The study was conducted by researchers from Harvard Medical School, who examined the data of 25,848 men who participated in a 10-year prospective cohort study. Among men who were questioned about their use of Viagra, 142 had melanoma, 580 had Squamous Cell Carcinoma, and 3,030 had Basal Cell Carcinoma. As a result, the researchers indicated that Viagra was “significantly associated with altered risk of melanoma” and opined that Viagra may impact the body’s ability to fight off skin cancer because it lowers levels of the cancer-fighting protein PDE5A.

In June 2015, a study from Dr. Stacy Loeb at NYU Langone Medical Center in New York City found that “the bottom-line is that we found no evidence of a causal relationship between any type of erectile dysfunction drug and an increased risk for either melanoma or basal cell carcinoma.” The study, which received no funding from the pharmaceutical industry, is published in the June 23, 2015 issue of JAMA. Dr. Loeb found that men who took the ED drug had a 21% higher risk for melanoma, but stated that there was “no evidence that taking a higher dosage of any of these drugs led to a higher risk of melanoma,” and that evidence of such a
dose-response relationship would be key to confirming that the medications could cause skin cancer. Loeb opined that the increased melanoma risk was likely tied to lifestyle factors that men who take impotence medications indulge in, such as tanning, rather than the pills themselves.

On April 7, 2016, the Judicial Panel on Multidistrict Litigation transferred all federal cases to the Northern District of California. In this litigation, plaintiffs allege Pfizer knew that Viagra posed a cancer risk and purposely hid facts about the drug’s safety. In addition, plaintiffs contend that Pfizer failed to sufficiently test the link between the use of the drug and the risk of deadly melanoma before the FDA approved it. Lastly, plaintiffs contend that even when studies were done that linked Viagra to an increased risk of melanoma, Pfizer failed to warn users about the important risks associated with Viagra use and instead, continued to spend millions of dollars to promote the drug.