Reuters has found that drug companies have been hiking the prices of widely used drugs, sometimes more than doubling their cost.

Since 2011 the price of 4 out of 10 of the most widely used drugs in the U.S. has risen over 100%, according to Reuters. The other six increased by over 50%. Consumers, employers and government health programs were left facing increased costs for drugs for arthritis, high cholesterol and asthma that ran into the billions.

Drug Companies Raise Prices Of Popular Meds

Drug companies under increasing pressure over prices

Turing Pharmaceuticals spiked the price of Daraprim, an antiparasitic, by more than 5,000 percent, drawing attention to drug prices. Another incident involving Valeant also shocked the public, but smaller price increases still add up.

AbbVie Inc raised the price of the arthritis drug Humira by over 126%. Amgen Inc and Teva Pharmaceutical Industries Ltd raised prices for arthritis drug Enbrel and multiple sclerosis drug Copaxone by 118%.

When Reuters pressed the drug companies on their pricing, they claimed they were set to recoup investments in failed drugs, drive further research and development effors, as well as supporting clinical trials.

Pharma chiefs defend pricing structure

Some drug companies claimed that they offered discounts and rebates which meant that many drugs sold for far less than the prices found by Reuters.

However Dr. Steve Miller, chief medical officer of top U.S. pharmacy benefit manager Express Scripts Holding Corp (ESRX.O), told Reuters that the current trend for drug price increases is “not sustainable.”

Politicians have been taking more of an interest in drug price increases and the topic has been part of debates on the presidential campaign trail. However industry figures claim that price gougers such as Turing and Valeant are not symptomatic of the whole industry.

“Our industry invests on average 20 percent of our revenues into research and development. It’s a fundamentally different business model,” said Robert Zirkelbach, a spokesman for industry lobby Pharmaceutical Research and Manufacturers of America, or PhRMA.

Three of the drug companies which have top 10 drugs, Sanofi SA (SASY.PA), Teva, Amgen, J&J and AstraZeneca, say that they help low income consumers by offering discounts.

According to Peter Bach, an oncologist at the Memorial Sloan Kettering Cancer Center, patients would be better off if drug prices weren’t so reliant on bargaining power. As it stands the drug “companies have complete control over pricing in the United States,” he said.