An investigation into pharmaceutical drug pricing has been launched following the widely-publicized, steep price increases of certain drugs, the Senate’s Special Committee on Aging announced Wednesday.

Led by Senators Susan Collins (R-ME) and Claire McCaskill (D-MO), the bipartisan investigation has requested documents from four pharmaceutical companies whose drugs have seen recent, “dramatic” price increases.

Those companies include Turing Pharmaceuticals, which recently made headlines when it hiked prices of Daraprim, an antiparasitic, from $13.50 a pill to $750.

“The sudden, aggressive price hikes for a variety of drugs used widely for decades affect patients and healthcare providers and the overall cost of health care,” wrote Collins in a press release. “These substantial increases have the potential to inflate the cost of healthcare for Americans, especially our seniors, by hundreds of millions of dollars each year.”

The panel’s investigation will focus on steep price increases for off-patent drugs, mergers within the pharmaceutical industry and the Food and Drug Administration’s role in the approval process for generic drugs. The committee noted the importance of the issue for seniors, who account for 34% of all prescription drug use.

The committee has an initial hearing on the topic slated for December 9.