A drug best known for treating erectile dysfunction may offer the first real hope for children with Leigh syndrome, a rare and often fatal disorder that attacks the brain and muscles. Researchers from Charité – Universitätsmedizin Berlin and collaborators across Germany reported in the journal Cell that sildenafil — the active ingredient in Viagra — significantly improved symptoms in a small group of patients, according to Science Daily.
Leigh syndrome is caused by defects in the body's cellular energy production. Because cells cannot generate enough power, the brain and muscles bear the heaviest toll. Children typically develop seizures, muscle weakness, paralysis, and developmental delays in infancy or early childhood. The disease progressively worsens, and life expectancy is significantly reduced. No approved drug treatments currently exist.
In a pilot study of six patients ranging from 9 months to 38 years old, continuous sildenafil treatment produced measurable improvements within months. Many patients showed stronger muscles, and some experienced notable neurological gains. Patients also recovered more quickly from metabolic crises — sudden overloads of energy metabolism that can cause sharp declines.
The results in individual cases were striking. "In the case of a child undergoing sildenafil treatment, the walking distance increased tenfold, from 500 to 5,000 meters," explained Prof. Markus Schuelke, a physician and scientist at Charité's Department of Pediatric Neurology. "In another child, the therapy completely suppressed metabolic crises that occurred almost monthly, while another patient no longer suffered from epileptic seizures."
Sildenafil is classified as a PDE-5 inhibitor and is already used in infants to treat pulmonary hypertension because of its ability to widen blood vessels. The researchers identified this existing safety profile as one reason the drug could be repurposed for Leigh syndrome. While the study is small and preliminary, the findings represent a rare glimmer of progress for families facing a disease that has long had no pharmacological options.
