WASHINGTON – Federal Trade Commission Chairman Jonathan Leibowitz said this week he is considering whether to open a formal investigation into the 2007 merger that created CVS Caremark Corp., Bloomberg News reported.

The news came as Change to Win, a union federation representation 6 million workers, said FTC staff has scheduled a second meeting for Oct. 15 to assess the union’s charges of anti-competitive practices by CVS Caremark. FTC representatives declined to comment.

“I can’t talk about what we are doing in terms of investigations, but we have certainly met with a number of people who have an interest in CVS Caremark,” Leibowitz, who met with Change to Win last month, told Bloomberg. “There are some serious allegations raised, and we’ll listen to these people.”

CVS has come under increasing fire in recent months from Change to Win, independent pharmacists and lawmakers unhappy about the 2007 merger of CVS Corp. and Caremark Rx Inc.

Leibowitz said the FTC has the authority to re-examine a completed merger, although it rarely uses it. “It’s very unusual for us to look at a consummated merger but sometimes we do,” he told the news service. “You look at it from the point of view of the consumer.”

In an e-mail, CVS spokeswoman Carolyn Castel told Bloomberg the company was unaware of the pending meeting.

“We have no information regarding a meeting between [Change to Win] and the FTC,” she said. “For more than two years, CTW has been making false statements about our company and mischaracterizing our business practices because we refuse to waive the right of our employees to vote confidentially in union elections.”

The CVS Caremark merger “has enhanced the ability of our company to offer payers and consumers more accessible, effective and affordable pharmacy health care services,” Castel added.