New use of old drug: Sildenafil Citrate (Viagra) improves amniotic fluid index in oligohydramnios.

Pfizer.com 

Sildenafil Citrate (Viagra) improves amniotic fluid index in pregnancies complicated by oligohydramnios according to a new study published ahead of print on March 6,2017 in Journal of Obstetrics and Gynecology.[1]

Viagra, a specific phosphodiesterase-5 inhibitor, has recently been proposed as a potential therapeutic strategy to maintain placental function and increase the amniotic fluid index (AFI).

This was an open-label randomized trial, carried out over a period of one year and recruited a total of 184 women. The study included all women at 30 weeks or more in pregnancy with oligohydramnios detected during routine sonography. No specific cause or etiology was detected for oligohydramnios in all these women.

The women were randomized to receive either Sildenafil Citrate 25 mg three times a day along with intravenous infusion of 2 L isotonic solution (82 women) or just fluids only (84 women). All women were hospitalized for initial 24 hours and received the IV fluids.  

The women were followed up for 6 weeks on the basis of outpatient monitoring with NST, USG and biophysical profile. Patient is readmitted if the AFI drops below 5 for Intravenous fluid therapy. Final assessment of the amniotic fluid volume is done at 6 weeks or before delivery if she went into labor before completing 6 weeks.

It was seen that women who received Sildenafil have considerable good amniotic fluid at follow up with AFI of 11.5 vs 5.4 in the control group. (P=.02).

The women in sildenafil group also went further into pregnancy with mean gestational age of 38.3 weeks as compared to 36 weeks. (P=.001). These women had one third the rate of Cesarean section and one fourth neonatal intensive care admission as compared to placebo group.

The authors concluded that “Sildenafil citrate increases amniotic fluid volume in pregnancies complicated by oligohydramnios.”

The proposed mechanism is vasodilatation of small myometrial vessels, thereby increasing the placental perfusion which leads to improvement in amniotic fluid index, fetal weight, and even uterine and umbilical artery Doppler patterns.

Currently there is no effective therapy for early onset IUGR or oligohydramnios.

Sildenafil citrate in the same dose has also shown promising results in improving the birth outcomes in early and late onset IUGR.[2]

Preliminary studies have also shown that it is effective in early onset preeclampsia to improve fetal growth retardation, but more randomized trials are needed.[3]

The trial is registered with Clinicaltrials.gov number NCT02372487

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[1] http://journals.lww.com/greenjournal/toc/publishahead

[2] http://www.ijrcog.org/index.php/ijrcog/article/viewFile/1603/1429

[3] https://obgynupdated.blogspot.com/2016/07/new-use-of-old-drug-sildenafil-citrate.html