Washington, D.C. ? House Democrats are investigating whether FDA Commissioner Andrew von Eschenbach lied under oath about the antibiotic Ketek, which has long been under scrutiny by Congress.

The seriousness of the inquiry was outlined in a letter sent Thursday to Health and Human Services Secretary Mike Leavitt. The letter requested that the department make available by the close of business Wednesday all documents used to prepare von Eschenbach for his testimony. Also, the lawmakers asked Leavitt to make available all senior staff and counsel who participated in preparing him for his testimony.

The Food and Drug Administration approved Ketek in 2004 to treat respiratory tract infections, bronchitis, sinusitis and community-acquired pneumonia. However, in February, the agency restricted the drug’s use only to treat pneumonia.