Horizon Pharma, Opiant fall amid Elizabeth Warren concern about pharma deals (update)
JHVEPhoto/iStock Editorial via Getty Images

Update 6:55am: Adds Amgen comment. 
Horizon Pharmaceuticals (NASDAQ:HZNP) dropped 1.6% on a report that Sen. Elizabeth Warren (D-MA) told the Federal Trade Commission she has concerns about Amgen's (NASDAQ:AMGN) plan to buy Horizon Therapeutics (HZNP) and Indivior's plan to buy Opiant Pharmaceuticals (NASDAQ:OPNT). Opiant fell 2%.
"Given these companies' records of anti-competitive business practices, these acquisitions could cause further price increases on lifesaving drugs and prevent affordable alternatives from entering the market," Warren wrote in a letter Wednesday to FTC Chairwoman Lina Khan as well as two other Democrat FTC Commissioners.
"Both Amgen and Horizon have engaged in brazen price increases on drugs that face little or no competition, while Amgen has abused the patent process, creating patent thickets to evergreen their products, prevent generic competition, and maintain market dominance," Warren wrote in the letter.
Warren specifically highlighted Amgen's "most egregious price hike" on its drug Enbrel. 
Amgen commented on Warren's letter in an email to Seeking Alpha. 
 "We disagree with Senator Warrenâs characterization of Amgen and our planned acquisition of Horizon Therapeutics," Amgen said in a statement. "We have been working cooperatively with the Federal Trade Commission and remain confident there are no anti-competitive aspects of this transaction. Amgenâs commercial, medical, and manufacturing capabilities will make it possible for Horizonâs life-changing medicines to reach many more seriously ill patients."
Amgen agreed to buy Ireland-based biotech Horizon Therapeutics (HZNP) for nearly $27.8 billion in cash last month. Indivior (OTCPK:INVVY) agreed to acquire opioid overdose therapy maker Opiant (OPNT) for $145 million in November.
"The FTC should strongly consider Indivior's history of anti-competitive and deceptive practices when evaluating how Indivior might behave after this potential transaction is completed," Warren wrote.
Indivior responded to Warren's letter.
"The opioid addiction crisis continues to devastate our families and communities," Nina DeLorenzo, Chief Global Impact Officer at Indivior said in a statement. "Opiantâs nalmefene rescue therapy medication, which is currently not approved by the FDA, will be an important additional option to help those who suffer an opioid overdose, and with Indiviorâs and Opiantâs combined resources and expertise we can launch this therapy, when approved, more effectively. Together our companies can fight this problem."
Warren is not new to being critical of M&A in the U.S. In recent months she has asked the FCC to block Tenga's (TGNA) sale to Standard General deal as well and for the FTC to block Kroger's (KR) planned purchase of Albertsons (ACI).
News of the Warren letter was earlier reported by Reuters.
In March Warren and Rep. Mondaire Jones (D-NY) introduced legislation to block deals worth more than $5B or that lead to high market shares.