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Sildenafil, commonly known as “Viagra”, is a drug currently used to treat male erectile dysfunction. Because of its role in relaxing blood vessels, research has been used to improve the blood supply to the placenta of pregnant women to help the development of the fetus. However, at present, more than ten pregnant women have taken lung infection and died after taking sildenafil. The clinical trial of the drug was urgently stopped.

Sildenafil is a drug used to treat male erectile dysfunction and is generally known under the trade name “Viagra”. The clinical trial, which was stopped, was attended by the University of Amsterdam Academic Medical Center and 10 other Dutch hospitals. The study was originally designed to use this drug to improve maternal placental blood supply to help the fetus.

A total of 183 pregnant women participated in the trial, 93 of whom were randomized to sildenafil and the remaining women used placebo. Of the pregnant women taking sildenafil, 17 were born with lung disease, and 11 of them died. Among other pregnant women who used placebo, 3 had lung disease, but no baby died.

At present, the specific cause of death in infants with lung disease is still under investigation. Wessel Ganzevoort, a Dutch maternity doctor who led the study, believes that sildenafil may increase the risk of lung disease in children and increase after birth. Mortality.

The main author of the study, Wessel Ganzevoort

It is reported that this study is aimed at pregnant women with early intrauterine growth restriction, which often leads to more serious consequences such as premature birth, low birth weight, fetal or neonatal death, but there is no effective treatment.

At present, the Dutch health department has been involved in this incident. The drug trial for pregnant women started in 2015 and was originally scheduled to end in 2020.

 

Viagra helps the fetus grow?

 

Viagra was originally entered into a clinical trial by Pfizer Inc. in the United States to treat cardiovascular disease. The researchers hope that it can relax the cardiovascular smooth muscle by releasing the biologically active substance nitric oxide to relieve cardiovascular disease. In the first clinical trial, the effect did not meet the researchers’ expectations and did not become a drug for the treatment of cardiovascular disease. However, this drug has improved the sex life of the subject. It was later found that sildenafil was able to relax the vascular smooth muscle of the corpus cavernosum, which increased blood flow, congestion of the cavernous body, and erection of the penis, thereby producing a therapeutic effect on penile erectile dysfunction.

Later, it was discovered that sildenafil has the effect of dilating pulmonary blood vessels, which has become a drug for patients with pulmonary hypertension.

Around 2000, scientists began to interest in how it helped the fetus. In the case of limited intrauterine growth, the fetus cannot obtain enough blood, causing the fetus to fail to grow normally in the mother’s womb, and the fetus that stops growing will die in the womb. At present, the treatment for this problem is to induce premature delivery of the fetus and to be born in advance before the life of the fetus is at risk. This does not seem to solve the underlying problem.

Doctors think that if sildenafil can increase the blood supply to the fetus, it may help the fetus grow in the womb.

The results of the animal trials were good, so in 2004, Canadian doctors started a small clinical study, 10 pregnant women with severe early intrauterine growth restriction took sildenafil, and 17 did not take Pregnant women in sildenafil were compared. Studies have found that sildenafil increases the growth rate of the fetus and also increases the survival rate of the fetus and the baby. No adverse side effects were found throughout the study. Therefore, researchers believe that sildenafil may be an innovative approach to treating fetal growth restriction. However, the data from this study is not sufficient to guide clinical applications, and a large number of randomized controlled trials are needed.

As a result, a larger international cooperation began, and Canada, New Zealand, Australia, the United Kingdom, and the Netherlands participated in the trial, called STRIDER, for a larger randomized controlled trial.

“Although there have not been enough clinical trials, doctors have given sildenafil to patients abroad and have achieved good results,” said Wesel Ganzevoot, a doctor who led the Dutch clinical trial, in an interview with local Dutch media.

At present, the relevant trials in New Zealand, Australia and the United Kingdom have ended, and the UK has already published their results in The Lancet. From the results of the current release, the results are not satisfactory.

British article in The Lancet

In the UK, researchers from November 21, 2014 to July 6, 2016 recruited 135 women for clinical trials, randomly assigned 70 women to sildenafil, and 65 women were given a placebo. The results showed that sildenafil did not have the expected effect on pregnant women and fetuses. Eight more severe cases were reported in the study, of which 6 occurred in the placebo group and 2 in the sildenafil group. The trial showed that sildenafil did not contribute to fetal growth and development, but there were no serious adverse consequences associated with sildenafil.

 

What is the cause of the baby’s death?

 

It is too early to explain why there are adverse consequences in clinical trials in the Netherlands, but one of them has attracted attention. In a press release, the University of Amsterdam Medical Center, which leads the Dutch clinical trial, pointed out that in the trial, 93 pregnant women were taking sildenafil, and 19 infants died, 11 of which were probably due to “pulmonary hypertension”, while Westland That has not been approved for the treatment of pulmonary hypertension in adults.

According to Robert Tulloh of the University Hospital of Bristol, if the patient suddenly stops taking sildenafil, it will have an adverse effect. Over time, the body adapts to the drug, just as taking steroids can cause the body to produce less natural steroids. Now, imagine that the fetus relies on the growth of sildenafil in the mother’s womb. When they are born, their lungs need to start working suddenly, but they have no support from sildenafil.

Sildenafil is approved for pulmonary hypertension in adults, but its use in newborns and children remains controversial. In 2012, the US FDA issued a warning against sildenafil for children between the ages of 1 and 17. This warning is based on the results of long-term clinical trials in which the mortality rate of children taking high doses of sildenafil is much higher than that of children taking low doses. Therefore, the FDA has indicated in the drug label that sildenafil is not recommended for pediatric patients.

However, in 2014, the US FDA issued a clarification message stating that the previous recommendation not to recommend sildenafil for pediatric patients does not mean that children are completely unusable. Some medical institutions see it as a taboo and refuse to give sildenafil to pediatric patients. It should be noted that for each child, a balance should be struck between risk and benefit. If there is no other choice, sildenafil can be given to children under close supervision. However, in newborns, especially premature babies, they are still not in the range of indications.

In an interview with the BBC, the University of Liverpool professor Zarcko Alfirevic, who is responsible for some of the UK research, believes that clinical trials in the Netherlands require in-depth research because no similar complications have occurred in the UK, Australia and New Zealand studies that have ended before. .

Although no adverse consequences have been reported in clinical trials in Canada, clinical trials in Canada have been suspended.

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