Sen. Susan Collins, R-Maine, expressed some doubt over a portion of President Trump's drug pricing plan that would require companies to list the cost of medications in their commercials.

"I'm not convinced that's the answer, but we do need to address that," Collins said, answering a question about how it's often difficult for consumers to know how much their prescription drugs cost.

The ad pricing proposal is one of several put forward by the Trump administration to lower the cost of drugs for patients. A recent poll from the Kaiser Family Foundation found that it has support from 76 percent of the public.

Collins said she was concerned that patients would tune out when given these advisories because several factors play into how much a customer ultimately pays for drugs. It's possible that all the different contingencies would be listed in an ad, including whether someone is insured or covered under Medicare, or mentioned that rebates could be part of the ultimate cost of a drug, she said.

"I don't know how you would figure out what price to list," she said, but stressed that better transparency on pricing was important. "We have to find a better way to figure out this opaque system."

Collins has supported measures intended to lower drug prices. She has introduced legislation that would ban “gag clauses” that block pharmacists from letting patients know about less expensive drugs.

Collins, who was speaking at the Pew Charitable Trusts in Washington, expressed dismay at the way drug companies raise their prices "literally overnight" while blocking cheaper, generic drugs from coming to market.

She took several shots at Martin Shkreli, the former Turing Pharmaceuticals CEO who became infamously known as "pharma bro" in 2015 after it raised the price of the drug Daraprim from $13.50 a pill to $750 a pill. The company has changed its name to Vyera Pharmaceuticals.

Collins pointed to an interview in which Shkreli was asked why the company raised drug prices, saying, "He answered simply, 'Because I could.'"

"His truly is the face of this egregious business practice," she said.

Shkreli is now serving a seven-year sentence in federal prison in New Jersey for securities fraud. He was convicted of defrauding hedge-fund investors and of manipulating the company's stock.

Collins said when drug companies raise their prices it "devastated patients and families across our nation." She described scenarios that patients use to get around the higher prices, including by either going without medicine or taking lower doses of the drug than what their doctor has recommended.

"I don't know how these companies live with themselves, I must say," Collins said.

[Also read: HHS Secretary Alex Azar: New round of drug price hikes a ‘tipping point’]