The Federal Trade Commission will allow pharmaceutical giant Amgen to move ahead with its acquisition of Horizon Therapeutics, averting a trial set for September.

In a news release Friday, the US antitrust regulator said it accepted a proposal from Amgen that would allow the $27.8 billion deal under multiple conditions, including that Amgen would not pressure insurance companies and pharmacies to bundle two of Horizon's medications with its own best-selling drugs.

In May, the FTC filed a complaint in the US District Court for the Northern District of Illinois to stop the deal from going ahead, alleging that it was anti-competitive. This is the first time in 14 years that the commission had brought a case against a pharmaceutical merger.

The lawsuit involved Horizon's Tepezza, used to treat thyroid eye disease, and Kystexxa, used to treat chronic refractory gout. Both are the only FDA-approved products to treat their respective diseases. The FTC's concern was that, by acquiring these products, Amgen would stifle competition by making it harder for consumers to have access to cheaper medicines if they were developed by competitors.

In a news release Friday, Amgen said it "has consistently stated to the FTC, the courts and the public that it has no reason, ability or intention to bundle Horizon's (Tepezza or Krystexxa) with any of its products. This narrow assurance ... will have no impact on Amgen's business."

Amgen is also required to alert the FTC if it plans on acquiring any medications that treat thyroid eye disease or chronic refractory gout. It also needs to gain approval from the FTC before acquiring any other companies that manufacture these types of medicines. This prior approval process will be in place through 2032.

The two companies are expected to finalize the merger later this year, according to Amgen.