SECTION 8LL. Filling of remaining portion of prescription for covered drug that is a narcotic substance earlier filled in lesser quantity

Any contract between a subscriber and the corporation under an individual or group hospital service plan that is delivered, issued or renewed within the commonwealth shall provide, for any covered drug that is a narcotic substance contained in schedule II pursuant to chapter 94C and subject to cost sharing, that if a person receives a prescription filled in a lesser quantity pursuant to section 18 of said chapter 94C, said person shall not be subject to an additional payment obligation, including but not limited to co-payments, if said person fills the remaining portion of the prescription.