SECTION 17P. Filling of remaining portion of prescription for covered drug that is a narcotic substance earlier filled in lesser quantity

The commission shall provide, to an active or retired employee of the commonwealth who is insured under the group insurance commission, 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, that person shall not be subject to an additional payment obligation, including but not limited to co-payments, if that person fills the remaining portion of the prescription.