US drugmaker Mylan is facing a probe from the Federal Trade Commission (FTC) as to whether it has violated antitrust laws in protecting its EpiPen from lower-priced competitors, according to news agency Bloomberg.

In response, Mylan said it had received a request for information from the FTC “months ago” as part of a preliminary investigation, while at the same time maintaining it had not acted improperly to prevent generic competition.

The disclosure comes some four months after the Canonsburg, Pennsylvania-headquartered group agreed to pay a settlement of $465 million to the US Department of Justice (DoJ) on claims relating to the misclassification of EpiPen and overcharges under the Medicaid drug rebate program.

As well as any antitrust violations, the FTC is also said to be looking at whether Mylan made small changes to its EpiPen in order to shield it from competition, and whether or not the company entered into any agreements to delay cheaper versions appearing on the market.

EpiPen is a self-administered injection of epinephrine, used to treat potentially fatal allergic reactions. While there are other injectable epinephrine allergy drugs available, there has been no direct generic competitor for EpiPen to date.

A version by Israeli generics producer, Teva Pharmaceutical Industries, was rejected by the Food & Drug Administration (FDA) last February because it had two caps as opposed to the one cap on Mylan’s product. Teva said last November that it expects to have a generic version on the US market in early 2018.

Meanwhile, Mylan itself launched an authorized generic version of the allergy drug last December. The epinephrine injector has a wholesale cost of $300 per two-pack, which is more than 50% below the price of its EpiPen Auto-Injector.

The FTC investigation follows a backlash by the US Congress over prices for the EpiPen. President Donald Trump also launched a verbal attack on drugmakers last month, accusing them of charging “astronomical” prices and “getting away with murder.” He subsequently met with pharma executives on Jan. 31, to discuss the industry’s issues and present his planned reforms.