WASHINGTON — Some low-cost generic drugs that have helped restrain health care costs for decades are seeing unexpected price spikes of up to 8,000 percent, prompting a backlash from patients, pharmacists and now Washington lawmakers.

A Senate panel met Thursday to scrutinize the recent unexpected trend among generic medicines, which usually cost 30 percent to 80 percent less than their branded counterparts.

Experts said there are multiple, often unrelated, forces behind the price increases, including drug ingredient shortages, industry consolidation and production slowdowns due to manufacturing problems.

But the lawmakers convening Thursday’s hearing said the federal government needs to assume a bigger role in restraining prices.

“If generic drug prices continue to rise then we are going to have people all over this country who are sick and need medicine and who simply will not be able to buy the medicine they need,” Vermont Sen. Bernie Sanders, who chairs the Senate Subcommittee on Primary Health and Aging.

Sanders introduced a bill that would require generic drugmakers to pay rebates to the federal Medicare and Medicaid programs when prices of their medications outpace inflation.

The Generic Pharmaceutical Association said in a statement released  Thursday that the 10 drugs cited by lawmakers do not reflect the broader U.S. market, which includes 12,000 generic medications that have reduced drug costs by billions.