The Oklahoma Health Care Authority terminated three physicians from participating in the federal Medicaid program and is reviewing the status of 10 others after their names showed up on top 10 lists of physicians writing the most prescriptions for frequently abused pain and mood altering medications, The Oklahoman has learned.

U.S. Sen. Charles Grassley, R-Iowa, sent a letter to the authority last April requesting lists of the top 10 Oklahoma writers of Medicaid prescriptions for OxyContin, Xanax and six other pain and antipsychotic medications.

â€œThe overutilization of prescription drugs, whether through drug abuse or outright fraud, plays a significant role in the rising cost of our health care system,â€ Grassley said in the letter to the Oklahoma Health Care Authority.

Grassley said in a letter to Human Services Secretary Kathleen Sebelius that he has been requesting records nationwide in an effort to identify â€œoutlierâ€ doctors who have issued prescriptions for certain drugs in much greater quantities than their colleagues.