Okla. Stat. tit. 74, § 1307.1

No employee or dependent who participates in a health maintenance organization (HMO) through the Oklahoma Employees Insurance and Benefits Act shall be denied the right of changing the primary care physician to any other primary care physician within the HMO. The employee or dependent shall notify the HMO in writing of any change in the choice of primary care physician forty-five (45) days in advance of the change by certified mail with return receipt requested. Any such change in a primary care physician shall not be subject to the approval of the HMO, the Oklahoma Health Care Authority or state agency.