Okla. Stat. tit. 36, § 4511

A. No employer providing pharmacy services including prescription drugs to any employee or retiree of said employer, as part of a health care program, shall knowingly require the employee or retiree of said employer to obtain drugs from a mail order pharmacy as a condition of obtaining the employer's payment for such prescription drugs. B. Any person violating the provisions of this section, upon conviction, shall be guilty of a misdemeanor. Each such violation shall constitute a separate offense.