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| photo courtesy: Avon Pharmacy |
A recent study published online July 07, 2016 in journal of obstetrics and gynecology concluded that treatment with sildenafil citrate prolonged pregnancy by an average of 4 days compared with placebo.
Sildenafil
citrate, is a specific phosphodiesterase-5 inhibitor, augments the vasodilatory
effects of NO by preventing the degradation of cGMP causing
vasodilatation. Phosphodiesterase-5
is present in the human feto-placental circulation and sildenafil mediates
vasodilatation and improve fetoplacental circulation by the same mechanism of
action.[1]
This randomized, double blind placebo controlled trial recruited 100 patients with
preeclampsia between 24 and 33 weeks of gestation, into two groups, one
received 50 mg oral sildenafil citrate every 8 hours and other was put on
placebo.
The
patients also received additional antihypertensive treatment in the form of
α-methyldopa (500 - 1500 mg/day) along with pindolol (10 - 30 mg/per day) as
needed. Those patients who anticipated to go in labor received full
corticosteroid coverage within 72 hours.
Patients
in the treatment group on an average gained 4 days (14.4 days) as compared to
the placebo group (10.4 days). This group also observed an improvement in blood
flow in uterine and umbilical arteries (P< .001). and a significant
reduction in Maternal Arterial Pressure within 24 hrs of randomization (P <
.05).
Patients
in placebo group required increased dose of the primary drug or addition of the
new drug (P < .001).
Both
groups were comparable in terms of perinatal morbidity, mortality, or adverse
effects between groups. Each extra day gained between 24 and 32 weeks of
gestations helps to improve the infant mortality statistics.
To
confirm the benefits to the infant, "studies with a larger number of
patients and an earlier start of medication are required," the authors
opined.
The lead
author Alberto Trapani Jr, MD, PhD, quoted that "Reduction in maternal
[mean arterial pressure], without compromising uterine artery blood flow,
provides reassurance that sildenafil may be useful as an antihypertensive drug
in the context of placental vascular insufficiency."
Preliminary
studies have demonstrated use of sildenafil citrate in early onset preeclampsia
to improve fetal growth retardation, but more randomized trials and
meta-analysis are needed before a recommendation for its use can be made in
clinical practice. [2] A randomized
trial in 2009 demonstrated that although sildenafil does not prolong pregnancy
but it was well tolerated without any maternal or fetal adverse effects in the
escalating dose regimen 20-80 mg tid.[3]
[1] Maharaj
CH, O’Toole D, Lynch T, et al. Effects and mechanisms of action of sildenafil
citrate in human chorionic arteries. Reproductive Biology and
Endocrinology : RB&E. 2009;7:34. doi:10.1186/1477-7827-7-34.
P. von Dadelszen, S.
Dwinnell, L. A. Magee, B. C. Carleton, A. Gruslin, B. Lee, K. I. Lim, R. M.
Liston, S. P. Miller, D. Rurak, et al.
BJOG. 2011
April; 118(5): 624–628. doi: 10.1111/j.1471-0528.2010.02879.x
[3] http://www.ncbi.nlm.nih.gov/pubmed/19843000
