Creates provisions relating to insurance coverage of drugs

HB 877 requires Missouri health insurance plans (effective January 2026) to cover a prescribed drug without forcing patients to switch to a different medication first, unless their doctor provides written approval stating the switch is medically necessary for their health. This directly affects patients who receive prescriptions and their healthcare providers, preventing insurers from mandating alternative drugs without medical justification. The bill does not apply to step therapy protocols (already covered under existing law) or interchangeable biological drugs. It aims to give patients and doctors more control over medication choices within insurance coverage.