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.
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