Updated

The U.S. Senate's permanent subcommittee on investigations will probe Mylan Pharmaceuticals' pricing of the allergy auto-injector EpiPen, according to a press release issued on Wednesday.

The release described the probe as a "preliminary inquiry."

Mylan has been criticized - including by Democratic presidential candidate Hillary Clinton - for sharply raising the price of EpiPens, which are carried by people with life-threatening allergies. Mylan raised the price from about $100 in 2008 to about $600 currently. It has offered some discounts but this has done little to allay concerns.

More on this...

"Our review of this matter will be robust, thorough, and bipartisan. Parents and school districts in Ohio, Missouri and across the country need affordable access to this life-saving drug, and we share their concern over Mylan's sustained price increases," Senators Rob Portman, the Republican chair of the subcommittee, and Claire McCaskill, the top Democrat, said in a statement.

Mylan did not immediately respond to a request for comment.