Oral sildenafil citrate during labor mitigates the intrapartum decline in placental growth factor in term pregnancies

Safety and dose-finding trial of tadalafil administered for fetus in labor: A phase I clinical study

AIM

This study aimed to investigate the safety and efficacy of tadalafil in protecting the fetus from hypoxic stress caused by repeated labor pains during delivery and preventing fetal hypoxic-ischemic encephalopathy.

METHODS

The study used a three-case cohort approach. Three patients were administered 10 mg tadalafil and monitored for serious adverse events. In the absence of serious tadalafil-associated adverse events as assessed by the Safety Evaluation Committee, three new patients were added to the study and treated with 20 mg/dose. The blood levels of tadalafil were recorded before and after 2, 4, 8, and 12 h of administration and 2 h after delivery.

RESULTS

A total of seven patients were enrolled, and after excluding one patient who delivered before 37 weeks, tadalafil was administered to six patients. Maternal adverse events were considered acceptable from the maternal perspective, with grade 1 headache, anorexia, and myalgia and no obstetrical complications after delivery at both doses. No serious neonatal adverse events were associated with tadalafil. Tadalafil blood levels remained stable at both doses. In addition, the level of soluble fms-like tyrosine kinase-1 did not alter, while that of the placental growth factor differed significantly before and after tadalafil administration.

CONCLUSIONS

The study confirmed the safety of tadalafil administration during delivery for both mothers and newborns. The stable tadalafil blood levels confirmed the efficacy of the tested administration regime at 12 h interval. These findings would assist in conducting phase II trials to further verify the optimal dose and safety of tadalafil.

Sildenafil Citrate Downregulates PDE5A mRNA Expression in Women with Recurrent Pregnancy Loss without Altering Angiogenic Factors-A Preliminary Study

In our previous study, we showed that sildenafil citrate (SC), a selective PDE5A blocker, modulated NK cell activity in patients with recurrent pregnancy loss, which correlated with positive pregnancy outcomes. It was found that NK cells had a pivotal role in decidualization, angiogenesis, spiral artery remodeling, and the regulation of trophoblast invasion. Thus, in the current study, we determined the effects of SC on angiogenic factor expression and production, as well as idNK cell activity in the presence of nitric synthase blocker L-NMMA. Methods: NK cells (CD56⁺) were isolated from the peripheral blood of 15 patients and 15 fertile women on MACS columns and cultured in transformation media containing IL-15, TGF-β, and AZA—a methylation agent—for 7 days in hypoxia (94% N₂, 1% O₂, 5% CO₂). Cultures were set up in four variants: (1) with SC, (2) without SC, (3) with NO, a synthase blocker, and (4) with SC and NO synthase blocker. NK cell activity was determined after 7 days of culturing as CD107a expression after an additional 4h of stimulation with K562 erythroleukemia cells. The expression of the PDE5A, VEGF-A, PIGF, IL-8, and RENBP genes was determined with quantitative real-time PCR (qRT-PCR) using TaqMan probes and ELISA was used to measure the concentrations of VEGF-A, PLGF, IL-8, Ang-I, Ang-II, IFN–γ proteins in culture supernatants after SC supplementation. Results: SC downregulated PDE5A expression and had no effect on other studied angiogenic factors. VEGF-A expression was increased in RPL patients compared with fertile women. Similarly, VEGF production was enhanced in RPL patients’ supernatants and SC increased the concentration of PIGF in culture supernatants. SC did not affect the expression or concentration of other studied factors, nor idNK cell activity, regardless of NO synthase blockade.

Prelabor and intrapartum Doppler ultrasound to predict fetal compromise

According to current estimates, over 20% of the 4 million neonatal deaths occurring globally every year are related to intrapartum hypoxic complications that happen as a result of uterine contractions against a background of inadequate placental function. Most of such intrapartum complications occur among apparently uncomplicated term pregnancies. Available evidence suggests that current risk-assessment strategies do not adequately identify many of the fetuses vulnerable to periods of intermittent hypoxia that characterize human labor. In this review, we discuss the data available on Doppler ultrasound for the evaluation of placental function before and during labor in appropriately grown fetuses; we also discuss the current strategies for ultrasound-based risk stratification, the physiology of intrapartum compromise, and the potential future treatments to prevent fetal distress in labor and reduce perinatal complications related to birth asphyxia.

Changes in fetoplacental Doppler indices following intrapartum maternal sildenafil citrate treatment

OBJECTIVE

Uterine contractions during labour can result in a 60 % decline in fetoplacental perfusion, predisposing the fetus to hypoxic brain injury. Sildenafil citrate (SC) has shown promise in increasing uteroplacental perfusion as well as reducing the risk of operative birth for intrapartum fetal compromise (IFC). The aim of this study was to investigate the effect of intrapartum SC administration on fetoplacental blood flow indices.

METHODS

This was a subgroup analysis from an earlier Phase II double blind randomized controlled trial; assessing the effect of intrapartum SC administration (50 mg orally 8 -hly in labour) compared to placebo for the reduction of operative birth for IFC. An ultrasound scan measuring fetoplacental Doppler indices was performed prior to and 1-4 h after the administration of the first treatment dose.

RESULTS

Of the 300 women randomized to the main study, pre-treatment ultrasound scans were performed in 261 participants who received the study medication; paired pre- and post-treatment scans were performed in 70 (26.8 %). SC resulted in an increase in the middle cerebral artery pulsatility index (PI) z-score [+0.08 (1.35) vs.-0.12 (1.15)], a decline in the umbilical artery-PI z-score [-0.07 (0.96) vs. + 0.04 (1.25)] and an increase in the cerebroplacental ratio [MCA-PI/UA-PI] (CPR) z-score [+0.10 (1.13) vs.-0.26 (1.14)] although these failed to reach statistical significance. Amongst those with a pre-treatment CPR above the 5th centile, SC significantly reduced the risk of operative birth for IFC compared to placebo [logrank p = 0.02; hazards ratio 0.48, 95 % CI 0.29-0.77, p = 0.003].

CONCLUSION

Although the differences in Doppler indices pre- and post- SC treatment were non-significant, there was a clear trend towards a reduction in the UA PI, a corresponding increase in the MCA PI and a rise in post treatment CPR values suggesting potential improvement in fetoplacental Dopplers with intrapartum SC treatment. However this study was limited by the small sample size. The results of this hypothesis generating study suggest that it may be possible to stratify women that would most benefit from this intervention based upon their pre-labour CPR.