Melanoma Skin Cancer: FDA Is Evaluating The Need For Regulatory Action; More Lawsuits Filed; Another Research Study
In late June 2016 the Food and Drug Administration (FDA) said it will study a potential link between melanoma skin cancer and erectile dysfunction (ED) drugs such as Viagra, Cialis, and Levitra.
This announcement appeared in the agency's latest watch list of drugs with possible safety issues, "January - March 2016: Potential Signals of Serious Risks/New Safety Information Identified from the FDA Adverse Event Reporting System (FAERS)". In relevant part, the document listed these drugs which have been associated with melanoma as a serious side effect.
Adcirca (tadalafil; Eli Lilly and Company): tablets
Cialis (tadalafil; Eli Lilly and Company): tablets
Levitra (vardenafil hydrochloride; GlaxoSmithKline): orally disintegrating tablets
Revatio (sildenafil citrate; Pfizer): tablets, oral suspension, and injection
Staxyn (vardenafil hydrochloride; GlaxoSmithKline): orally disintegrating tablets
Stendra (avanafil; Vivus and Auxilium Pharmaceuticals): tablets
Viagra (sildenafil citrate; Pfizer): tablets
From this July 1, 2016 Medscape article, "New FDA Watch List: Possible ED Drug–Melanoma Link and More", we get some background information about that June 2016 FDA investigation announcement:
The agency will be on the heels of other researchers when it comes to the class of ED drugs called phosphodiesterase (PDE)-5 inhibitors. A study published in JAMA Internal Medicine in April 2014 found an association between sildenafil and an increased risk for melanoma. However, the authors said their epidemiological evidence was not strong enough to change clinical recommendations for treating ED.
Likewise, a study published in JAMA in June 2015 did not nail down a cancer risk for these drugs. Mining a massive health database of Swedish patients, the authors reported that among 4000 men diagnosed with malignant melanoma, use of a PDE-5 inhibitor was linked to a 20% increase in the relative risk for the cancer.
On the legal front, a growing number of Viagra - melanoma lawsuits have been filed against the drug company Pfizer. The federal court cases were consolidated in April 2016 before U.S. District Judge Richard Seeborg in the Northern District of California. Those Viagra cases are now part of a multidistrict litigation which often goes the short name "Viagra federal court MDL 2691".
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In more detail, from the April 7, 2016 Transfer Order (PDF document) issued by the United States Judicial Panel on Multidistrict Litigation (JPML): "These actions share actual questions arising out of the allegation that Viagra (sildenafil citrate) causes or increases the risk of developing melanoma and that Defendant failed to warn consumers and health care providers of the alleged risk."
As regards the general nature of these Viagra - melanoma lawsuits, many of the filed Complaints include allegations along these lines:
- Pfizer knew Viagra posed a cancer risk and purposely concealed facts regarding the drug’s safety;
- Pfizer failed to sufficiently investigate the link between Viagra and an increased risk of melanoma prior to
FDA approval; and,
- Pfizer failed to warn users about the link between Viagra and the increased risk of melanoma even after studies showed the
association, and instead continued promotion of the product.
And that last point brings us back to the medical developments concerning melanoma and the use of Viagra, Cialis, Levitra, and other medicines in the PDE-5 inhibitor class of drugs.
According to a study published in mid-June 2016 by the journal PLOS Medicine, some researchers from the UK found that men who took Viagra, Cialis, and Levitra had only a very slight increase in the risk of developing melanoma compared to a control group, with that risk appearing to be explained by greater exposure to the sun (as opposed to these ED drugs).
From the Abstract for this medical journal article, "Phosphodiesterase Type 5 Inhibitors and Risk of Malignant Melanoma: Matched Cohort Study Using Primary Care Data from the UK Clinical Practice Research Datalink", we get this overview of that medical research. We start with the Background section
Laboratory evidence suggests that reduced phosphodiesterase type 5 (PDE5) expression increases the invasiveness of melanoma cells; hence, pharmacological inhibition of PDE5 could affect melanoma risk. Two major epidemiological studies have investigated this and come to differing conclusions. We therefore aimed to investigate whether PDE5 inhibitor use is associated with an increased risk of malignant melanoma, and whether any increase in risk is likely to represent a causal relationship.
Then we jump down to the Conclusions section:
Our results were not consistent with PDE5 inhibitors being causally associated with melanoma risk, and strongly suggest that observed risk increases are driven by greater sun exposure among patients exposed to a PDE5 inhibitor.
We will continue to monitor both the legal and medical aspects of this still-emerging drug safety issue concerning Viagra, Cialis, Levitra, and similar drugs.
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