215 ILCS 175/15
In accordance with the Pharmacy Practice Act, when a prescribing physician has indicated on a prescription "may not substitute", a health insurance policy or health care service plan that covers immunosuppressant drugs may not require or cause a pharmacist to interchange another immunosuppressant drug or formulation issued on behalf of a person to inhibit or prevent the activity of the immune system of a patient to prevent the rejection of transplanted organs and tissues without notification and the documented consent of the prescribing physician and the patient, or the parent or guardian if the patient is a child, or the spouse of a patient who is authorized to consent to the treatment of the person.
Except as provided by subsections (a), (b), and (c) of Section 20 of this Act, patient co-payments, deductibles, or other charges for the prescribed drug for which another immunosuppressant drug or formulation is not interchanged shall remain the same for the enrollment period established by the health insurance policy or plan.
215 ILCS 175/15