HAVERFORD, Pa. — Philadelphia's Transportation Authority has filed a lawsuit against Gilead Sciences Inc. over the pricing of its hepatitis C drug.

Sovaldi is a highly effective pill treatment for the most common form of hepatitis C without the injections and unpleasant side effects of earlier treatments.

Gilead has been selling a 12-week treatment of Sovaldi in the United States for approximately $84,000, or $1,000 per pill. That has raised complaints by insurers, politicians and patient advocates, particularly because millions of Americans could benefit from the drug.

The complaint was filed in federal court. It says Sovaldi's cost prohibits many patients from getting treatment and accuses Gilead of "unjust enrichment" that violates antitrust law.

The Foster City, California, company could not be reached immediately for a comment Wednesday.