Children
with a rare lung disorder, called pulmonary arterial hypertension,
may begin taking Pfizer
Inc.'s drug Viagra in order to
treat blood pressure-related problems associated with the
disorder.
Viagra is
a drug normally used for erectile dysfunction and also helps adults
with pulmonary arterial hypertension gain the ability to exercise by
relaxing the arterial wall, which leads to decreased pulmonary
arterial pressure and resistance. It blocks an enzyme that regulates
flow in the penis and lungs.
This
medication works for pulmonary arterial hypertension because what
this disorder does is increase the blood pressure in the pulmonary
vein, artery or capillaries leading to fainting, dizziness
and shortness
of breath. It causes the right side of the heart to work harder,
and Viagra releases this pressure.
U.S.
regulators are looking for a way to test whether Viagra would be okay
for children. Advisors to the Food and Drug Administration will meet
July 29 to discuss this matter and see if Pfizer's study on the
pill's effectiveness on children is "sufficient."
Pfizer
conducted a study that consisted of 234 children who took Viagra. In
most studies of adults with the disorder, they are asked to perform
exercise tests. However, this was much too difficult for the
children, so a different test where a catheter is inserted through
the arteries (which measures blood flow) was conducted instead. This
alternative test proved that the
drug failed to show any differences when the children tried
regular exercise tests, but when researchers used the alternative
measure of blood flow, Viagra did prove to be beneficial.
"It's
a good option in pediatric patients because it is well-tolerated, in
that it doesn't have as many side effects as some of the other
options," said Chad Knoderer, a pediatric clinical pharmacist at
Riley Hospital for Children in Indianapolis, who has used Viagra for
children with the disorder before.
Pulmonary
arterial hypertension affects 600 people a year, and if Pfizer meets
FDA requirements, the drug will be on the market an extra six months
without generic competition. The patent for the drug is expected
to expire in 2012.
