U.S. Senator Elizabeth Warren (D-MA) speaks during a Senate Finance Committee hearing on the nomination of Chris Magnus to be the next U.S. Customs and Border Protection commissioner, in the Dirksen Senate Office Building on Capitol Hill in Washington, DC
U.S. Senator Elizabeth Warren (D-MA) speaks during a Senate Finance Committee hearing on the nomination of Chris Magnus to be the next U.S. Customs and Border Protection commissioner, in the Dirksen Senate Office Building on Capitol Hill in Washington, DC, U. Reuters / POOL

Senators Elizabeth Warren and Amy Klobuchar and 11 other U.S. lawmakers pressed the president of the biggest pharmaceutical industry trade group on Tuesday about what they said were "troubling price increases for brand name drugs" in January.

A letter to Stephen Ubl, president of the Pharmaceutical Research and Manufacturers of America (PhRMA) was signed by 12 Democrats as well as Senator Bernie Sanders, an independent. It asks PhRMA to explain the source of the price increases, and asks for information about research costs and revenue from the medicines.

"The large, across-the-board price increases of popular, brand name prescription drugs appear to be an example of pharmaceutical companies taking advantage of their abusive market power to expand already large profits," the lawmakers wrote.

The lawmakers, who included Representative Katie Porter, cited two studies: one by Dr. Stephen Schondelmeyer of the University of Minnesota and another by the Johns Hopkins Drug Access and Affordability Initiative, which focused on 20 prescription medicines that the Medicare Part D program spends the most on.

Schondelmeyer's study found that drugmakers increased prices for 72% of the 100 top-selling drugs in early 2022, with 26% of brand name drugs showing higher prices.

The Johns Hopkins study found higher prices for 16 of the top 20 Medicare Part D drugs in January.

Among the widely used drugs in the Medicare program cited in the letter were Novo Nordisk's Victoza 2-Pak for type 2 diabetes, which had a price increase of 4.8% to $709.74.

Novo Nordisk spokesman Michael Bachner in a statement said that the company "committed in 2016 to keep annual list price increases below 10% and we have kept true to that commitment."

Other drugs cited included AbbVie's big-selling rheumatoid arthritis treatment Humira Pen and leukemia drug Imbruvica, which saw their prices go up 7.4%. The price of Pfizer's breast cancer drug Ibrance rose 6.9%, while the price of blood clot preventer Eliquis, sold by Bristol Myers Squibb and Pfizer increased 6%, the letter said.

Representatives for PhRMA and other drugmakers did not immediately respond to requests for comment.