Republican Sen. Chuck Grassley is demanding answers from a key drug company on why the vital allergic medication EpiPen has increased by more than $500 in some cases.

The Iowa senator wrote a letter to the CEO of Mylan, which distributes the drug, to ask why the "much-needed medication" has seen an increase in price. He asked about whether the company offers any patient assistance programs for providing the drug, and singled out help given to schools.

Grassley noted that the price increases, which have ranged in some cases of up to $500, are affecting school budgets.

"It follows that many of the children who are prescribed EpiPens are covered by Medicaid and therefore the taxpayers are picking up the tab for this medication," Grassley wrote.

He added that the price increase can create "an unsafe situation for patients as people untrained in medical procedures are incentivized to make their own kits from raw materials."

The EpiPen price hike is the latest to garner attention. Other types of drugs that have increased in price recently are for chronic conditions that include hepatitis C and cancer.

Political candidates on both sides of the aisle have sought to address the issue through different avenues. Grassley, for instance, has pushed to end pay-for-delay deals where a brand name drug maker pays a generic manufacturer to delay making a lower-cost generic alternative to a brand name drug.