Federal health regulators have granted tentative approval to a highly contested drug for muscular dystrophy that has become a flashpoint in the debate over patient access to experimental medicine.

The Food and Drug Administration said it cleared Sarepta Therapeutics' injection for a rare form of Duchenne muscular dystrophy, a deadly inherited disease that affects boys. It's the first FDA approval for the degenerative condition, which causes muscle weakness, loss of movement and eventually death.

Monday's announcement comes nearly five months after the agency and a panel of outside advisers panned the drug at a public meeting, saying there was little evidence of its effectiveness. But regulators faced an immense outcry from patient groups and physicians seeking access to the drug.