If the issuer of a health benefit plan, its delegated entity, or its employees or agents refuses to provide coverage for a prescription drug that is not included in a drug formulary, and the enrollee's physician or other health care provider with prescriptive authority has determined the prescription drug is medically necessary to treat a condition covered by the enrollee's health benefit plan, the refusal to provide coverage for the prescription drug constitutes an adverse determination for the purpose of Insurance Code Chapter 4201. An enrollee may appeal the adverse determination under Insurance Code Chapter 4201, Subchapters H and I, and the issuer of the health benefit plan, and its employees or agents, must review and resolve the appeal in accordance with those sections.