House Bill 4358 would amend the Insurance Code to prohibit insurers that deliver, issue for delivery, or renew a health insurance policy that provides prescription drug coverage in Michigan (“specified insurers”) from taking certain actions regarding that coverage. Specifically, a specified insurer could not remove a covered prescription drug from its list of prescription drugs or add utilization management restrictions to a formulary or reclassify a drug to a more restrictive drug tier or move a drug to a higher cost-sharing tier or a tier with a larger deductible, copayment, or coinsurance, unless certain conditions applied.