WASHINGTON — The head of a major pharmaceutical distributor apologized before Congress on Tuesday for not doing more to stop the shipment of millions of powerful prescription opioids to pharmacies in two small West Virginia towns, while another industry leader admitted that his company contributed to the nation’s opioid crisis.

Cardinal Health Executive Chairman George Barrett said he is sorry that the company did not act faster to halt millions of hydrocodone and oxycodone pills to the pharmacies in West Virginia, which has the nation’s highest rate of opioid overdose death.

“With the benefit of hindsight, I wish we had moved faster and asked a different set of questions,” Barrett said. “I am deeply sorry we did not. Today, I am confident we would reach different conclusions about those two pharmacies.”

Moments later, Joseph Mastandrea said that he believes his company, Miami-Luken, contributed to the opioid crisis.

Barrett and four current and former executives with pharmaceutical distributors that are accused of flooding small U.S. towns with prescription painkillers testified Tuesday morning before a House Energy and Commerce Committee oversight panel that has spent the past year investigating pill dumping in West Virginia.

In addition to Cardinal and Miami-Luken, executives from AmerisourceBergen, McKesson Corp., and H.D. Smith testified. All of the companies, aside from Miami-Luken, said they do not believe their companies contributed to the opioid crisis.

“I am so frustrated for the people in West Virginia and across this country that you all have not . . . stepped up and took more responsibility for this,” said Rep. David B. McKinley, R-W. Va., his voice rising. “The fury inside me right now is bubbling over.”

In February, the panel revealed in letters sent to the firms that McKesson and Cardinal Health shipped 12.3 million doses of powerful prescription opioids to the Family Discount Pharmacy in Mount Gay-Shamrock, West Virginia, from 2006 to 2014. The panel also is probing deliveries Cardinal made to the Hurley Drug Company in Williamson, West Virginia, which received more than 10.5 million pills during that same time period.

Cardinal said it has not distributed hydrocodone or oxycodone to the pharmacy in Mt. Gay-Shamrock since 2012 and has not sent the drugs to Williamson since 2014.

McKesson chief executive John Hammergren said the company distributed about 151 million doses of oxycodone and hydrocodone in West Virginia between 2007 and 2012, a fraction of the nearly 2 billion doses of all prescription medicines McKesson distributed in the state during that time frame.

“Put another way, West Virginia pharmacies overall were, and continue to be, very high volume customers for prescription drugs generally,” he said.

A single pharmacy in Kermit, West Virgina, a town of about 400 people, received nearly 9 million hydrocodone pills over two years.

“There is no logical explanation we can find for why a town of approximately 400 people would receive nearly 9 million opioid pills in two years,” said Rep. Greg Walden, R-Ore., chair of the Energy and Commerce Committee.

The subcommittee has spent the past year investigating the sale of pills in West Virginia by wholesale drug distributors, which are required by law to submit suspicious orders to the Drug Enforcement Administration. If the orders and sales are not correctly reported, it can facilitate the diversion of the drugs to the black market, where they are often sold at a premium, fueling addiction.

“We want to know what these companies knew about the rise of the opioid epidemic, when they knew it, and if it informed their distribution practices,” said Rep. Diana DeGette, D-Colo.

The hearing room was packed attorneys, lobbyists and staffers for the pharmaceutical industry and lawyers for counties, towns and cities suing the companies in a massive case that has been consolidated into a massive legal case in Cleveland. Many of the distributors are defendants.

Each executive said their companies have taken steps to prevent the diversion of drugs and to help fight the opioid crisis. They argued that their companies do not manufacture or prescribe drugs; they fulfill orders from pharmacies. Distributors, they argue, are not responsible for overprescribing medications. The companies also say that opioid painkillers account for a small portion of their overall business.

“As an intermediary in the pharmaceutical supply chain, Cardinal Health does not ultimately control either the supply of or the demand for opioids,” Barrett said.

Cardinal Health, AmerisourceBergen and McKesson are the nation’s three biggest pharmaceutical distributors, responsible for shipping nearly 85 percent of all prescription drugs in the United States. McKesson is the fifth-largest company in the country, with revenue of more than $192 billion, according to the Fortune 500 list. Cardinal ranked 15th, with $121 billion in revenue.

Committee members are hoping Tuesday’s hearing might shed light on data the companies reported to the DEA about pill orders. That information is kept in a confidential DEA database known as the Automation of Reports and Consolidated Orders System. The database tracks the flow of prescription painkillers from manufacturers to distributors to pharmacies.

Cardinal Health was fined $44 million in 2016 to resolve allegations that it failed to report suspicious orders of narcotics. In 2008, Cardinal paid a $34 million fine to settle similar allegations.

McKesson agreed to pay $150 million in fines in January to resolve allegations that it failed to report suspicious orders of narcotics. In 2008, the company paid a $13 million fine for similar allegations.

Rep. Kathy Castor, D-Fla., asked Hammergren why McKesson kept shipping massive quantities of opioids to small towns despite having agreed to the terms of the settlements.

“You saw paying the penalties on the settlement agreements was a cost worth paying because you were making so much money?” she asked.

“Any settlement with a regulator, we take very seriously,” Hammergren said.

“I think this was the opposite of due diligence,” said Castor, who also noted that Hammergren personally made hundreds of millions of dollars from 2007 to 2017.

The companies also have come under fresh scrutiny from Attorney General Jeff Sessions, who said in an interview with The Washington Post that he would have tough questions for the executives if he were still in Congress.

“This has been a colossal detriment to America, and you have profited enormously by it,” Sessions said he would tell them. “And I’m not shedding any tears if you’re no longer making profits.”