(a) The executive commissioner, in the rules and standards governing the Medicaid vendor drug program and the child health plan program, shall require prior authorization for the reimbursement of a drug that is not included in the appropriate preferred drug list adopted under Subchapter E unless:
(1) the drug is exempt from prior authorization requirements by federal law; or
(2) the executive commissioner is prohibited under Sections 549.0252 and 549.0253(a) from requiring prior authorization for the drug.
(b) The executive commissioner may require prior authorization for the reimbursement of a drug provided through any state program, other than a program described by Subsection (a), that the commission or a state health and human services agency administers, including a community mental health center and a state mental health hospital if the commission adopts a preferred drug list under Subchapter E that applies to that facility and the drug is not included in the appropriate list.
(c) The executive commissioner shall require that the prior authorization be obtained by the prescribing physician or prescribing practitioner.