(Adds Amgen comment, Mylan no comment, background)
NEW YORK, July 31 (Reuters) - Pharmacy benefit manager Express Scripts Holding Co said on Monday it would favor drugmaker Mylan Inc's versions of the EpiPen lifesaving allergy treatment over the allergy auto-injectors of other companies.
The nation's largest pharmacy benefit manager said it was excluding alternatives to the auto-injector made by Impax Laboratories Inc, privately held Kaleo and A-S Medication from its widely used list of covered drugs.
Express Scripts has been excluding certain medicines from its coverage list or formulary since 2014, citing concern about costs to its health insurers and corporate customers.
By excluding drugs from its coverage list, Express Scripts said it has been better able to negotiate lower prices from drugmakers, and will save customers an estimated $2.5 billion in 2018, up from $1.8 billion this year.
Mylan faced severe criticism and congressional and legal investigations last year after it doubled the cost of a pair of EpiPens to around $600, enraging consumers and putting it in the center of the ongoing debate over the high cost of prescription medicines in the United States. It has since offered its own generic version for about $300 in response to the furor.
Mylan declined to comment on the Express Scripts decision.
Express Scripts added 64 new drugs - including the EpiPen alternatives - to its list of drugs excluded from insurance coverage for 2018. The list determines whether millions of people with private insurance can easily use an insurance co-pay to buy medicine.
Another important drug excluded from the company's coverage this year is Neupogen, an Amgen Inc treatment used to boost infection-fighting white blood cells during chemotherapy.
Amgen said retail use of Neupogen through the Express Scripts formulary accounted for only about 1.7 percent of U.S. Neupogen sales in 2016.
Express Scripts listed as its "preferred alternatives" to Neupogen the biosimilars Granix and Zarxio, made by Teva Pharmaceutical Industries Ltd and Novartis AG , respectively.
Unlike generics of simple pills, it is not possible to manufacture exact copies of complex biotech medicines made from living cells. As a result, less expensive biosimilars must prove they are similar enough in safety and efficacy to be sold as alternatives.
"Amgen feels strongly that Neupogen is competitively priced based on its clinical and economic value," Amgen said in an emailed statement. (Reporting by Michael Erman and Bill Berkrot; Editing by Matthew Lewis)