German researchers have discovered that sildenafil, the active ingredient in Viagra, may offer a treatment for Leigh syndrome, a rare and fatal genetic childhood disease. In a pilot study, six patients aged nine to 38 who took daily doses of sildenafil for up to seven years showed improvements in muscle strength, neurological function, and metabolic symptoms.
Leigh syndrome affects one in 36,000 children worldwide and currently has no approved treatments. Half of children born with the disease die before age three, according to the National Institutes of Health. Symptoms include loss of motor skills, vomiting, seizures, muscle weakness, nerve damage, and impaired function of the respiratory, heart, and kidney systems.
Dr. Markus Schuelke of Charité – Universitätsmedizin Berlin, lead author of the study, said in a statement: '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.' The team is planning a Europe-wide clinical trial to further test the drug.
Patients in the pilot study took low or medium doses of sildenafil, ranging from 0.66 mg to 3 mg daily—a fraction of typical Viagra doses (25–100 mg). Improved circulation from the drug helped treat pulmonary hypertension, a complication of Leigh syndrome, and led to enhanced walking ability, language comprehension, and nerve cell function. One child's walking distance increased tenfold, from 500 to 5,000 metres, while another saw a complete suppression of monthly metabolic crises, and a third experienced no further epileptic seizures.
Tests on lab-grown tissue and animals showed similar benefits. Rodents and pigs with Leigh syndrome lived longer when treated with sildenafil. Two of seven pigs with fatal cases survived more than two months, with one remaining stable for six months. The researchers caution that larger studies are needed to confirm these findings.
