The leaders of a Senate panel are condemning four companies for aggressively increasing prices for prescription drugs. They say the companies have exploited a system lacking in competition to hike prices for critically needed medicines.

An investigation by the Senate Special Committee on Aging focuses on Turing Pharmaceuticals, Valeant Pharmaceuticals, Retrophin Inc. and Rodelis Therapeutics. The first two faced especially harsh criticism.

“The Turing and Valeant price spikes have been egregious,” Sen. Susan Collins, the Maine Republican who heads the panel, declared at a hearing Wednesday.

Public outrage exploded this fall after news that Turing increased by more than 5,000 percent the price of a drug used to treat a life-threatening infection: from $13.50 to $750 per pill.

Drug-price spikes have occurred with increasing frequency over the last few years.

(AP)