Missouri Revised Statutes Title XXII. Occupations and Professions § 338.202. Maintenance medications, pharmacist may exercise professional judgment on quantity dispensed, when

1. Notwithstanding any other provision of law to the contrary, unless the prescriber has specified on the prescription that dispensing a prescription for a maintenance medication in an initial amount followed by periodic refills is medically necessary, a pharmacist may exercise his or her professional judgment to dispense varying quantities of maintenance medication per fill, up to the total number of dosage units as authorized by the prescriber on the original prescription, including any refills. Dispensing of the maintenance medication based on refills authorized by the physician or prescriber on the prescription shall be limited to no more than a ninety-day supply of the medication, and the maintenance medication shall have been previously prescribed to the patient for at least a three-month period. The supply limitations provided in this subsection shall not apply if the prescription is issued by a practitioner located in another state according to and in compliance with the applicable laws of that state and the United States or dispensed to a patient who is a member of the United States Armed Forces serving outside the United States.

2. For the purposes of this section, “maintenance medication” is and means a medication prescribed for chronic long-term conditions and that is taken on a regular, recurring basis; except that, it shall not include controlled substances, as defined in and under section 195.010.