By Diane Bartz

WASHINGTON (Reuters] – On Tuesday, Senators Elizabeth Warren/Amy Klobuchar joined 11 other U.S. senators to press the President of the most powerful pharmaceutical industry trade association about the “troubling” price hikes in brand-name drug prices that occurred in January.

Twelve Democrats and Senator Bernie Sanders signed a letter addressed to Stephen Ubl (PhRMA), president of Pharmaceutical Research and Manufacturers of America. The letter asks PhRMA for explanations about the reason behind the increase in prices and requests information on research costs and revenues from the sale of medicines.

The lawmakers stated that the large price rises of prescription drugs of brand names across all categories appear to show how pharmaceutical companies are taking advantage of their market power in order to increase profits.

Rep. Katie Porter was among the lawmakers who cited two studies by Dr. Stephen Schondelmeyer of University of Minnesota and one by Johns Hopkins Drug Access and Affordability Initiative. The latter focused on the 20 most prescribed medicines the Medicare Part D program spent the most money on.

Schondelmeyer found that the price of 72% of the top 100 drugs was increased by drugmakers in 2022. 26% of brands had higher prices.

Johns Hopkins’ January study revealed that 16 out of 20 top Medicare Part D medications saw higher prices in January. More than half showed price increases exceeding 5%.

The letter cited Novo Nordisk’s Victoza 2-Pak, a drug for type 2 diabetes that is used widely in Medicare programs. It was reportedly priced at $899.91 per two months.

Michael Bachner from Novo Nordisk stated that Victoza 2-pak prices rose 4.8% in January to $709.74. In a separate statement, he stated that Novo Nordisk “committed to maintaining annual list prices below 10% in 2016, and that we have maintained that commitment.”

Others drugs mentioned included AbbVie’s Humira Pen, a popular rheumatoid arthritis drug that is highly-seller and the leukemia drug Imbruvica. Their prices increased 7.4%. Prices of Pfizer The price of breast cancer medication Ibrance, which is available at NYSE:), rose 6.9% while that for blood clot prevention Eliquis (which was sold by Bristol Myers (NYSE):) Squibb and Pfizer, increased 6%.

Representatives of PhRMA, as well as other drug manufacturers, did not respond immediately to inquiries for comment.