NeoNotes Journal Club
Andrew B. Kairalla MD, Editor
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Viagra
for Pulmonary Hypertension
The mechanism by which inhaled nitric oxide (iNO) treats persistent pulmonary hypertension in the newborn (PPHN) is by stimulation of guanylate cyclase, the enzyme which converts GTP to cyclic GMP (cGMP). Sildenafil (Viagra) can also cause an increase in intracellular cGMP levels by inhibiting an enzyme (phosphodiesterase V) which breaks down cGMP. Oral Sildenafil has been shown to be a potent selective pulmonary vasodilator in animal studies, in adult humans, and in a small number of babies with PPHN. It can augment the effects of iNO, and can be used to help wean patients off of iNO. Pfizer is currently organizing randomized, controlled trials to investigate the use of Sildenafil in PPHN.
Comment.
The early data on Viagra
(either alone or in combination with iNO) for the treatment of PPHN looks
promising. Unfortunately, we’ll
have to wait some time before we have sufficient data on efficacy, dosage and
safety in neonates. This therapy
is not yet ready for “prime time”, and should not be used outside of
randomized, controlled trials. ABK.
Additional Comments:
Date: 03 Jan 2003
Time: 18:59:49
From theoretical point of view, Viagra is a potent vasodilator, but I really
doubt the selective pulmonary vasodilator effect of Viagra, becuse of that it is
contraindicated in adult with cardiac disease.... occasionally I have some
problems with iNO especially during weaning (Rebound phenomina). I believe this
is due inhibition of endogenous NO, which could be overcome by using Viagra.
I am really looking forward for Pfizer study...
UserName: Dr.Hesham Al-Girim,MD
Institution: NWAFH
telephone: 0096644411088
email: hgirim@health.net.sa
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