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Viagra

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Viagra is synonymous with fixing male erectile dysfunction. Not surprisingly, more than 45 million men tried “the little blue pill,” Pfizer’s highest-selling drug. But new evidence links the drug to melanoma, a deadly skin cancer.

What is Viagra?

Viagra holds the distinction of being the first oral medication introduced for erectile dysfunction (ED) in the United States. Manufactured by Pfizer and approved by the FDA in 1998 to treat impotence in men, “the little blue pill” instantly became Pfizer’s highest-selling drug. Worldwide, the blockbuster ED drug brought in just under $2 billion for Pfizer in 2013, and doctors continue to write millions of prescriptions for the drug.

Viagra (sildenafil citrate) was conceived as a treatment for chest pain (angina) and pulmonary arterial hypertension – high blood pressure in the vessels that carry blood to the lungs. Clinical trials results showed the drug as a poor choice as a heart medication, but researchers noticed increased erections in men who volunteered for the study. Pfizer resubmitted the drug for approval to treat ED.

Erectile dysfunction affects approximately 40 percent of men by age 40 to some degree and nearly 70 percent of men by age 70, according to the Cleveland Clinic. More than 45 million have taken Viagra.

How Does Viagra Work?

PDE5 Inhibitor

Classified as a PDE5 inhibitor, Viagra works by blocking certain enzymes in the body, causing blood vessels to dilate and enhancing blood flow to the penis. In conjunction with sexual stimulation, the drug-induced blood flow aids in producing and maintaining erection.

Sildenafil and Pulmonary Treatment

Sildenafil is also sold under the brand name Revatio in tablet form or oral suspension form. It is approved by the FDA for the treatment of pulmonary arterial hypertension in adults, and works by dilating blood vessels that supply the lungs with blood.

Viagra and Melanoma Skin Cancer

Recent studies link Viagra to an increased risk of melanoma, the deadliest form of skin cancer. Most men who end up taking Viagra are in their 50s or older, and this group of men is also at the highest risk for melanoma. If the cancer is found early, people are more likely to survive.

The survival rates for melanoma are estimated based on the stage of the cancer. Doctors determine the stage of cancer by how far the cancerous cells spread in the body. At stage I, the cancer is still local and easy to remove, and by stage IV, the cancer spreads to lymph nodes and other organs. The five-year survival rate for stage I is 92 to 97 percent, while stage III survival rate ranges between 40 and 78 percent. The rate for stage IV is 15 to 20 percent.

2014 Study Results

A 2014 study found sildenafil increased risk of the deadly cancer by nearly double. Researchers included 25,848 men who took sildenafil over a 10-year period in the study and published their results in The Journal of the American Medical Association (JAMA). Even men who took the drug for a short time had a higher risk.

Monitoring for Early Signs

Researchers think Viagra causes melanoma by causing cells in the skin called melanocytes to increase production of melanin, a substance responsible for tanning skin. When this happens, these cells grow too large and may cause cancer to form. Men who take Viagra and their doctors should monitor for early signs of the disease.

Serious Side Effects

Viagra comes with some risk of side effects. These serious ones require immediate medical attention:
Sudden and severe vision loss in one or both eyes Blurred vision
Sudden hearing loss or decrease Tinnitus or ringing in the ears
Dizziness Fainting
Chest pain Difficulty breathing
Rash Erection that is painful or lasts more than 4 hours

Other Side Effects

Mild to moderate side effects associated with this drug can include:

  • Headache
  • Stomach problems
  • Sleep problems
  • Numbness and tingling in limbs
  • Altered vision
  • Muscle Pain

Drug Interactions

Viagra can interact with other drugs, which can change its effectiveness and the significance of some side effects.

Nitrate Drugs

Nitrate drugs are often used to boost the amount of oxygen flowing to the heart and to ease pains associated with conditions such as angina. Taking Viagra with nitrate drugs can cause a serious drop in blood pressure, leading to dizziness, fainting and rarely, heart attack or stroke.

Alpha Blockers

Alpha blockers are commonly used to treat high blood pressure and certain prostrate conditions. Similar to nitrate drugs, taking Viagra with alpha blockers can cause a serious drop in blood pressure, leading to dizziness, fainting and rarely, heart attack or stroke.

Anti-Fungals

Certain anti-fungals, such as itraconazole, ketoconazole, some antibiotics, such as clarithromycin, erythromycin, protease inhibitors used in the treatment of HIV or hepatitis, and some seizure medications can interfere with Viagra metabolism, making it more difficult to clear the drug from the body and increasing risk of side effects.

Lawsuits

Former Viagra users have filed numerous lawsuits against the company through the years related to varying significant side effects.

Skin Cancer Lawsuits

Skin cancer is the latest side effect that may land Pfizer in court. There is no warning for skin cancer on the drug's package.

Heart Attacks and Strokes

Skin cancer was not the first deadly disease linked to sildenafil. The first group of lawsuits focused on heart events. Using the medication can cause a sudden drop in blood pressure, which can lead to heart attacks and strokes.

Vision and NAION

A second set of men filed lawsuits related to Non-Arteritic Ischemic Optic Neuropathy (NAION), which causes issues with vision, including blindness. There is now a section on the Viagra warning label for this condition, and some men may be at greater risk.