Dutch study assessing sildenafil in pregnant women stopped after deaths and adverse events

A study involving pregnant women has been stopped immediately at a Dutch university after an increased risk of death and adverse effects for the baby after birth were revealed in the interim results.

The study, being carried out at ten Dutch hospitals, started in 2015 and was focused on pregnant women who had a serious growth limitation in early pregnancy and were given a poor prognosis for the child. It was thought that, as found in previous studies on animals, sildenafil (also known as Viagra) would have a positive effect on the growth of the babies.

Sildenafil is a drug commonly used to treat erectile dysfunction and can be prescribed for patients with high blood pressure. It works by dilating blood vessels and it was this function that was shown to improve the function of the placenta in previous research in rats.

Half of the patient population had been administered with sildenafil and half had been given a placebo. At the time of cessation there were a total of 183 women included in the study.

The potential detrimental effects of the medication on the babies after birth were discovered in the interim analysis that was performed by Amsterdam UMC. In this analysis, it was found that with treatment there was a potentially increased risk of a disease of the blood vessels of the lungs and an increased risk of death.

All adverse effects occurred after birth with the researchers finding no positive effect on the children for other outcomes.

Every participant in the study has been approached personally and been informed as to whether they were administered sildenafil or placebo. Also, Canadian researchers performing a similar trial have been informed of the results and have temporarily stopped their work.

As reported in The Guardian, leader of the research, Wessel Ganzevoort, a gynaecologist, said in an interview with the Dutch daily newspaper De Volkskrant: “We wanted to show that this is an effective way to promote the growth of the baby. But the opposite happened. I am shocked. The last thing you want is to harm patients.”

The research, which was due to end in 2020 was intended to assess the safety and efficacy of the drug as it has sometimes been given to pregnant women ‘off-licence’ to promote growth of the unborn baby. The adverse effects seen in this study were unknown until now and the researchers of the study expect the use of sildenafil in this capacity will not be stopped worldwide.

At the time of the study termination 93 women in total had been administered sildenafil. Of these 19 babies died, 11 of whom were due to a possible lung disease, a form of high blood pressure in the lungs. A further six babies also had this lung disease, but did not die. About 10 to 15 women are waiting to find out if their babies have been affected by the drug or not.

In the placebo group, which comprised 90 women, nine babies died although none died as a result of the lung disease. Three other babies in the placebo group had the lung disease but it did not cause death.

An extensive analysis of the available data will be performed and the children involved will be closely monitored as per the original study plan.