WASHINGTON — A U.S. Senate committee has begun a probe of recent spikes in pharmaceutical pricing.

Sens. Susan Collins (R., Maine) and Claire McCaskill (D., Mo.), who lead the Senate Special Committee on Aging, on Wednesday said the bipartisan investigation will include hearings, with the first slated for next month.

Sens. Susan Collins (R., Maine) and Claire McCaskill (D., Mo.)

The lawmakers noted that the inquiry comes in the wake of a series of media reports of drug price surges following the acquisition or merger of pharmaceutical companies. What’s more, they noted, the price hikes often involve older, off-patent medications.

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

“Given the potential harm to patients across our country who rely on these drugs for critical care and treatment, the Senate Special Committee on Aging considers these massive price increases worthy of a serious, bipartisan investigation into the causes, impacts and potential solutions.”

More than 40% of seniors take five or more prescription drugs per day, the senators reported, and seniors account for 34% of the all prescription medications used despite being just 13% of the population.

“Some of the recent actions we’ve seen in the pharmaceutical industry — with corporate acquisitions followed by dramatic increases in the prices of pre-existing drugs — have looked like little more than price gouging,” McCaskill said. “We need to get to the bottom of why we’re seeing huge spikes in drug prices that seemingly have no relationship to research and development costs. I’m proud to help lead this bipartisan investigation so that we can find some answers the public wants and deserves.”

Plans call for the committee’s investigation to examine substantial price increases on recently acquired off-patent drugs; mergers and acquisitions in the pharmaceutical sector that have sometimes triggered dramatic increases in off-patent drug prices; and the Food and Drug Administration’s role in the drug approval process for generic drugs, its distribution protocols and, possibly, the agency’s off-label regulatory regime.

The senators said they have requested documents and information from four pharmaceutical companies: Valeant Pharmaceuticals, Turing Pharmaceuticals, Retrophin Inc. and Rodelis Therapeutics. The requests focus on drugs that have seen recent, significant spikes in price.

“We seek your cooperation with this investigation so that the committee may better understand drug pricing and related regulatory and public policy concerns,” the senators’ letter to Turing Pharmaceuticals chief executive Martin Shkreli stated. “In particular, the committee wishes to learn more about Turing Pharmaceuticals’ recent acquisition of the rights to sell Daraprim, a drug used to treat and prevent infections, from Impax Laboratories and Turing’s subsequent decision to increase the price of Daraprim from $13.50 to $750 [per tablet].”

The committee has tentatively scheduled an initial hearing on the matter for Dec. 9 and will hold subsequent hearings, as needed, in the ensuing months.