Insulin makers accused of price collusion

U.S. congressmen last week asked the Department of Justice and the Federal Trade Commission to investigate three insulin makers for price collusion-the latest in concerns over insulin prices.

The pricing flap is just the latest in a series of Senate investigations and public outcry over the rising cost of prescription drugs. The most recent example was the EpiPen epinephrine injection (Mylan), which reportedly quadrupled in price since 2008.

Related: Drug maker pays out millions over EpiPen charges

The three major companies that produce insulin in the U.S.-Novo Nordisk, Eli Lilly and Sanofi-have hiked up the prices of their drugs between 380% and 400% since 2004, according to Truven Health Analytics, NBC News reported.

Often, the three raised prices for their insulin products-Novolog (Novo Nordisk), Humalog (Eli Lilly) and Lantus (Sanofi)-at the same time. That led to the letter from Senator Bernie Sanders (D-Vt.) and Representative Elijah Cummings (D-Md.), calling for an investigation.

“The original insulin patent expired 75 years ago. Instead of falling prices, as one might expect after decades of competition, three drug makers who make different versions of insulin have continuously raised prices on this life-saving medication,” the legislators wrote. “In numerous instances, price increases have reportedly mirrored one another precisely.”

Related: Cheaper generic EpiPen doesn't quiet critics

The cost of insulin more than tripled-from $231 to $736 a year per patient-between 2002 and 2013, the letter said. Plus, the companies raised prices 13 times simultaneously since 2009.

However, the three manufacturers denied the claims. “We strongly disagree with the accusations in the letter. The insulin market in the US is highly competitive,” wrote a spokesman for Eli Lilly, which sells Humalog and Humilin, STATreported. The spokesman also said the drugs’ net price has not increased since 2009 and pointed to the “complex reimbursement designs,” which place “an unfair burden on people with diabetes.”

“We set price for these life-saving medicines independently and then negotiate with payers and PBMs to ensure patients have access to them. We stand by our business practices,” wrote a spokesman for Novo Nordisk.

Read more: EpiPen discounts offered after pricing flap