Thousand Oaks-based Amgen is among a handful of drugmakers being probed for more information about a deal it reached with the Obama administration to support the health care overhaul Democrats passed in 2010, according to Bloomberg News.

The news agency reported on May 4 that a group of Republicans on the House Energy and Commerce Committee has requested documents about a deal that Amgen, Pfizer and Merck & Co. agreed to as the health care bill worked its way through Congress.

The drug companies agreed not to oppose a range of new taxes and discount their products in exchange for supporting a health care reform bill that would provide a potentially expanded customer base of insured Americans, Bloomberg reported.

An Amgen spokeswoman told the news agency that Amgen is aware of the probe. No subpoenas or formal letters have been sent, the news agency reported.