Cialis users sue Lilly, claiming drug has ties to skin cancer

Seven men who took Cialis pills to treat erectile dysfunction sued Indianapolis drugmaker Eli Lilly and Co. this week, claiming they later suffered from skin cancer that was related to the medicine.

The plaintiffs, from Ohio, Illinois, Texas and other states, filed separate but similar complaints Tuesday in U.S. District Court in Indianapolis, saying that Lilly knew or should have known the drug’s mechanism of action presented “significant risk of exacerbating melanoma.”

The suits cite studies in several medical journals that the plaintiffs claim link Cialis’ mechanism of action to melanoma. The mechanism, which inhibits an enzyme associated with flow of blood in the penis, is known as a PDE5 inhibitor.

One of the studies, published in the medical journal Cell Reports, determined PDE5 inhibitors lead to increased tumor growth, although that study did not specifically study the effects of Cialis, the suit said.

Another study, published in the Journal of the American Medical Association Internal Medicine, reported that users of a PDE5 inhibitor called sildenafil citrate, used in Pfizer’s erectile drug Viagra, exhibited an 84 percent increase in risk of developing or encouraging invasive melanoma.

The law firm that filed the suits, Cory Watson of Birmingham, Alabama, said it has filed more than 100 suits against Pfizer and more than 20 suits against Lilly in recent months.

“The pharmaceutical industry has known for a very long time that inhibition of PDE5 has been associated with an increased risk of melanoma,” said Kristian Rasmussen, a lawyer at the Alabama firm, which specializes in representing injury victims. “That information has slowly come to light over the last few years in the public domain.”

Lilly responded that it has reviewed the studies and has found no evidence that Cialis, also known as tadalafil, causes melanoma.

“We’ve reviewed data from multiple sources pertaining to melanoma skin cancer and tadalafil, and have concluded that based on the available data, a causal association has not been established,” Lilly spokesman Scott MacGregor wrote in an email. “Lilly and regulatory agencies continue to monitor this question.”

The plaintiffs, who took Cialis for periods ranging from one year to nine years, said they were treated for various skin cancers on fingers, chest, back and head.

The plaintiffs are alleging negligence, fraudulent misrepresentation, defective design and failure to properly test the drug and warn patients. They are seeking unspecified damages.

Cialis rang up sales of $2.3 billion last year.