Sildenafil (viagra) in infants
Sildenafil in the treatment of pulmonary arterial hypertension in infants ...
Definition
Pulmonary arterial hypertension(PAH) is a progressive, and often fatal,
debilitating disorder.
The increased pulmonary artery
pressure found in PAH is due to disturbances in key vascular mediator pathways
including relative deficiencies of vasodilators such as nitric oxide (NO) and
prostacyclin, as well as exaggerated production of vasoconstrictors such as
endothelin and thromboxanes.
Symptoms
Progressive breathlessness, exertion limitation, frequent decline and
failure of the right ventricle.
Mechanism of action of sildenafil
Sildenafil is a selective inhibitor of phosphodiesterase type 5 (PDE5).
Present throughout the body, PDE5 is found in high concentrations in the lungs.
Inhibition of PDE5 enhances the vasodilatory effects of nitric oxide in
pulmonary hypertension by preventing the degradation of cyclic guanosine
monophosphate (cGMP), which promotes relaxation of vascular smooth muscle and
increases blood flow. In animal models and human trials, sildenafil has been
found to produce a relatively selective reduction in pulmonary artery pressure
without adverse systemic hemodynamic effects after 3 months of oral therapy.
Inhibition of PDE5 by sildenafil may also enhance the platelet antiaggregatory
activity of nitric oxide and inhibit thrombus formation.
Infant’s dose
The protocol for dosing was
(1) first dose of 1 mg/kg/dose within 30 minutes admission or within 12
hours of delivery (whichever earlier),
(2) Dosing every six hours for a
maximum of 8 doses,
(3) Dose was doubled if the
oxygenation index (OI) or SpO2 did not improve (If OI continued to be <10%
of previous value and SpO2 was not increasing >5 of previous value) and
blood pressure remained stable.
how can i prepare the infant's dose
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newborns received oral Sildenafil solution
through feeding tube which was prepared by crushing a 50 mg tablet of
sildenafil in distilled water or simple syrup to make a concentration of 5
mg/ml.
notes
At 2012The U.S.Food and DrugAdministration (FDA) is recommending that
sildenafil not be prescribed to children (ages 1 through 17) for pulmonary
arterial hypertension. This recommendation against use is based on a recent
long-term clinical pediatric trial showing that: (1) children taking a high
dose of sildenafil had a higher risk of death than children taking a low dose
and (2) the low doses of sildenafil are not effective in improving exercise
ability.
References
1)
Clavecilla SQ. New insights into the treatment of pulmonary arterial
hypertension. Formulary, 2003 Mar; 38(3): 150-4, 157-8, 160.
2) Mehta S. Sildenafil for pulmonary arterial hypertension: exciting, but
protection required. Chest. 2003 Apr; 123(4): 989-92.
3) Pfizer Inc. FDA Approves Pfizer’s Revatio as Treatment for Pulmonary
Arterial
Hypertension.http://www.pfizer.com/pfizer/are/news_releases/2005pr/mn_2005_0606.jsp#additional.
Accessed June 23, 2005.
4) Kataoka M, Satoh T, Manabe T, Anzai T, Yoshikawa T, Mitamura H, Ogawa S.
Oral sildenafil improves primary pulmonary hypertension refractory to
epoprostenol. Circ J. 2005 Apr;69(4):461-5.
5) Kanthapillai P, Lasserson T, Walters E. Sildenafil for pulmonary
hypertension. Cochrane Database Syst Rev. 2004 Oct 18;(4):CD003562.
6) Karatza AA, Bush A, Magee AG. Safety and efficacy of Sildenafil therapy
in children with pulmonary hypertension. Int J Cardiol. 2005 Apr
20;100(2):267-73.
7) Leuchte HH, et al. Hemodynamic response to sildenafil, nitric oxide, and
iloprost in primary pulmonary hypertension. Chest. 2004 Feb; 125(2): 580-6.
8) Chockalingam A, Gnanavelu G, Venkatesan S, Elangovan S, Jagannathan V,
Subramaniam T, Alagesan R, Dorairajan S. Efficacy and optimal dose of
sildenafil in primary pulmonary hypertension. Int J Cardiol. 2005 Mar
10;99(1):91-5.
9) Lee AJ, Chiao TB, Tsang MP. Sildenafil for pulmonary hypertension. Ann
Pharmacother. 2005 May;39(5):869-84.
10) Sastry BK. Clinical efficacy of sildenafil in primary pulmonary
hypertension: a randomized, placebo-controlled, double-blind,
crossoverstudyImage. J Am Coll Cardiol, 2004 Apr;43 (7), pp. 1149-53.
11) Ng J, Finney SJ, Shulman R, Bellingan GJ, Singer M, Glynne PA.
Treatment of pulmonary hypertension in the general adult intensive care unit: a
role for oral sildenafil? Br J Anaesth. 2005 Jun;94(6):774-7.
12) American Heart Association rapid access journal report. Impotence drug
may help children with fatal lung disorder.
06/23/2005.http://www.americanheart.org/presenter.jhtml?identifier=3031499.
Accessed: June 23, 2005.
National Heart, Lung, and Blood
Institute: "What Is Pulmonary Arterial Hypertension?" National Heart,
Lung, and Blood Institute: "Living with Pulmonary Arterial
Hypertension." WebMD Medical News:"Viagra Label May Note Rare Vision
Problems. “ViagraThe Associated Press.
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