The effects of sildenafil citrate (Viagra) on uterine blood flow and well being in the intrauterine growth-restricted fetus.
OBJECTIVE
This study examined whether the type-5 phosphodiesterase inhibitor sildenafil citrate (Viagra; Pfizer, New York, NY) could increase uterine blood flow in intrauterine growth restriction (IUGR), thereby improving fetal oxygenation and well being.


METHODS
In fetal sheep, we induced IUGR at 105-110 days (0.7 gestation) using single umbilical artery ligation (SUAL). In SUAL and control animals, we measured uterine blood flow (UBF) and blood gases before and after sildenafil administration.


RESULTS
SUAL fetuses were hypoxemic compared with controls. Following sildenafil, UBF was significantly decreased in both SUAL and control ewes for approximately 40 minutes. In response to sildenafil, pO(2) was decreased in SUAL and control fetuses and both groups displayed significant hypotension and tachycardia. At postmortem SUAL fetal body weight was significantly reduced by 23% compared with controls.


CONCLUSIONS
Sildenafil does not improve UBF or fetal well being in SUAL-induced IUGR pregnancies and should be used with caution in IUGR and healthy pregnancies because of its detrimental effects on uteroplacental perfusion and on the fetus.
Monash Immunology and Stem Cell Laboratories, Monash University, VIC, Australia. suzie.miller@med.monash.edu.au
Suzanne L
SL
Miller
Jan M
JM
Loose
Graham
G
Jenkin
Euan M
EM
Wallace
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D020567:Fetal Weight / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011247:Pregnancy; D011687:Purines / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep / Q000097:blood / Q000196:embryology*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*; D014599:Uterus / Q000098:blood supply*
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate