Viagra Shows Promise as First Treatment for Fatal Childhood Disease Leigh Syndrome
Key Insights
Sildenafil, the active ingredient in Viagra, demonstrated significant improvements in muscle strength and neurological symptoms in six Leigh syndrome (search) patients aged 9 months to 38 years.
One child's walking distance increased tenfold from 500 to 5,000 meters, while another patient stopped experiencing seizures and two others showed cognitive improvements.
The European Medicines Agency (search) has granted sildenafil orphan drug designation for Leigh syndrome (search), paving the way for a larger placebo-controlled trial across Europe.
Sildenafil, the active ingredient in Viagra, has emerged as a potential breakthrough treatment for Leigh syndrome (search), a devastating childhood neurological disorder that typically proves fatal before age three. In a pilot study involving six patients, researchers from Charité – Universitätsmedizin Berlin and collaborating institutions reported significant improvements in muscle strength and neurological symptoms within just a few months of treatment.
Dramatic Clinical Improvements Observed
The results exceeded researchers' expectations. "For example, in the case of a child undergoing sildenafil treatment, the walking distance increased tenfold, from 500 to 5,000 meters," explained Dr. Markus Schuelke, lead clinical scientist at Charité's Department of Pediatric Neurology. The study treated patients ranging from 9 months to 38 years old, all showing measurable improvements.
Beyond mobility gains, the therapeutic effects extended to seizure control and cognitive function. One patient completely stopped experiencing epileptic seizures (search) after starting the medication, while two others demonstrated small improvements in cognitive ability. Perhaps most critically, patients recovered more quickly from metabolic crises – life-threatening emergencies that occur when the body cannot properly convert food into energy.
Addressing an Urgent Medical Need
Leigh syndrome (search) affects approximately one in 40,000 births, making it exceptionally rare but devastating for affected families. The disorder stems from genetic mutations that prevent mitochondria (search) from producing adequate energy, gradually starving critical tissues, particularly the brain and muscles, of necessary fuel.
"The low case numbers make it difficult to research the disease and present some obstacles in our urgent search for effective therapies," Schuelke noted. Early symptoms typically include vomiting, diarrhea, and difficulty swallowing, progressing to loss of motor skills, developmental delays, seizures, and breathing problems.
From Laboratory Discovery to Clinical Application
The path to identifying sildenafil as a treatment candidate required innovative research approaches. Scientists took skin cells from patients and converted them into induced pluripotent stem cells, then cultured nerve cells that exhibited the same metabolic defects as patients. This allowed researchers to screen over 5,500 approved drugs and compounds with established safety profiles.
"This is the largest drug screening for the treatment of Leigh syndrome (search) to date," said Dr. Ole Pless, lead author from the Fraunhofer Institute for Translational Medicine and Pharmacology (search). The screening revealed that sildenafil improved electrical functionality in cultured nerve cells.
Additional validation came from three-dimensional brain organoids, where sildenafil enhanced nerve cell growth, and animal models, where the drug improved energy metabolism and extended lifespan in mice and pigs carrying Leigh syndrome (search) mutations.
Safety Profile Supports Clinical Use
A crucial factor enabling the clinical trial was sildenafil's established safety record in pediatric populations. While best known for treating erectile dysfunction (search), the drug is already approved for treating pulmonary arterial hypertension (search) in children, providing extensive safety data for long-term pediatric use.
"Another decisive factor was the fact that detailed safety data was available for the long-term use of sildenafil in children, as the active ingredient is already approved for other pediatric disorders," explained Prof. Alessandro Prigione from University Hospital Düsseldorf (search).
The treatment was generally well tolerated, with only one patient discontinuing due to a rash. All other patients completed the treatment protocol without significant adverse effects.
Regulatory Recognition and Future Plans
The promising results have garnered regulatory attention. The European Medicines Agency (search) has granted sildenafil orphan drug designation for Leigh syndrome (search), enabling a simplified approval process designed to support rare disease therapy development.
Building on these preliminary findings, researchers are finalizing plans for a comprehensive Europe-wide placebo-controlled clinical trial as part of the SIMPATHIC EU project. The larger study aims to enroll 60 to 70 patients across several European countries to definitively establish sildenafil's efficacy.
"While we will have to confirm these initial observations in a more comprehensive study, we are very pleased to have found a promising drug candidate for the treatment of this serious hereditary disease," Schuelke emphasized.
The research team cautions families against attempting self-treatment until additional studies confirm these preliminary findings. However, the results published in Cell journal represent the first significant therapeutic advance for a condition that has remained without approved treatments, offering hope to families facing this devastating diagnosis.