Sildenafil is the phosphodiesterase-V inhibitor more commonly known as Viagra (1). It has been successful in treating pediatric pulmonary arterial hypertension (PAH) because it increases blood pressure in the lungs. It has grown in usage and is now the major treatment option for PAH in babies, even though it is still used off-label and requires further studies. For this reason, it should only be administered with the approval of the physician and with a pediatric cardiologist present.
Sildenafil combats pulmonary hypertension by decreasing the activity of phosphodiesterase-V, which is a substance in the lungs that breaks down another substance called cyclic guanosine monophosphate (GMP) (2). With phosphodiesterase-V in check, more GMP is available in the lungs. GMP relaxes and widens blood vessels in the lungs, which decreases the pulmonary blood pressure to the heart. This process decreases the blood pressure in the lungs and improves function.
Researchers are now testing the drug’s benefits for increasing blood flow in the brain and reducing brain damage in babies who have experienced birth asphyxia or hypoxic-ischemic encephalopathy (HIE) (3). Sildenafil was tested in rats who experienced birth asphyxia, and it was found that the drug reduced brain damage and functional deficits, such as movement issues. The drug was able to increase the number of nerve cells in the brain, decrease inflammation, and promote myelination (4). Higher doses were found to be more effective in reducing brain damage (3).
Researchers at McGill University in Canada are testing Sildenafil on human babies who have experienced birth asphyxia at Montreal Children’s Hospital. They have done preliminary studies that have shown positive results when the drug is administered within 48 hours of birth (5). According to one of the researchers, Dr. Wintermark, Sildenafil could reduce the impact of brain damage on babies, though it can not completely reverse it.
The results of these preliminary studies are powerful because although babies who experience birth asphyxia in developed countries can receive quick brain cooling treatments (therapeutic hypothermia), babies in less developed countries may not have access to these treatments. Sildenafil would be an incredible gift to these babies, because it is a low-cost drug that is easily accessible and easily administered. Dr. Wintermark notes that Sildenafil can be used anywhere in the world.
- Simonca, L., & Tulloh, R. (2017). Sildenafil in Infants and Children. Children (Basel, Switzerland), 4(7), 60. doi:10.3390/children4070060
- Sildenafil. (n.d.). Retrieved January 2, 2019, from https://phassociation.org/patients/treatments/sildenafil/
- Gulland, A. (2018, October 23). Viagra – the wonder drug that may boost the brains of babies starved of oxygen at birth. Retrieved December 28, 2018, from https://www.telegraph.co.uk/news/0/viagra-wonder-drug-may-boost-brains-babies-starved-oxygen/
- Goeller, A. (n.d.). Fulfilling our mission. Retrieved December 29, 2018, from https://www.hopeforhie.org/fulfilling_our_mission
- Sildenafil Administration to Treat Neonatal Encephalopathy – Full Text View. (n.d.). Retrieved January 2, 2019, from https://clinicaltrials.gov/ct2/show/NCT02812433