Generic substitutions, when, requirements - violations, penalty.
Mo. Rev. Stat. § 338.056
in effect338.056. Generic substitutions, when, requirements — violations, penalty. — 1. Except as provided in subsection 2 of this section, the pharmacist filling prescription orders for drug products prescribed by trade or brand name may select another drug product with the same active chemical ingredients of the same strength, quantity and dosage form, and of the same generic drug or interchangeable biological product type, as determined by the United States Adopted Names and accepted by the Federal Food and Drug Administration. Selection pursuant to this section is within the discretion of the pharmacist, except as provided in subsection 2 of this section. The pharmacist who selects the drug or interchangeable biological product to be dispensed pursuant to this section shall assume the same responsibility for selecting the dispensed drug or biological product as would be incurred in filling a prescription for a drug or interchangeable biological product prescribed by generic or interchangeable biologic name. The pharmacist shall not select a drug or interchangeable biological product pursuant to this section unless the product selected costs the patient less than the prescribed product.
2. A pharmacist who receives a prescription for a brand name drug or biological product may select a less expensive generically equivalent or interchangeable biological product unless:
(1) The patient requests a brand name drug or biological product; or
(2) The prescribing practitioner indicates that substitution is prohibited or displays "brand medically necessary", "dispense as written", "do not substitute", "DAW", or words of similar import on the prescription.
3. No prescription shall be valid without the signature of the prescriber, except an electronic prescription.
4. If an oral prescription is involved, the practitioner or the practitioner's agent, communicating the instructions to the pharmacist, shall instruct the pharmacist as to whether or not a therapeutically equivalent generic drug or interchangeable biological product may be substituted. The pharmacist shall note the instructions on the file copy of the prescription.
5. Notwithstanding the provisions of subsection 2 of this section to the contrary, a pharmacist may fill a prescription for a brand name drug by substituting a generically equivalent drug or interchangeable biological product when substitution is allowed in accordance with the laws of the state where the prescribing practitioner is located.
6. Violations of this section are infractions.
(L. 1978 H.B. 933, A.L. 1996 H.B. 1237, A.L. 2016 S.B. 875, A.L. 2018 S.B. 826, A.L. 2019 S.B. 514)
Source: Open US Law by Vaquill AI (CC BY 4.0)URL: https://revisor.mo.gov/main/OneSection.aspx?section=338.056Fetched: 10/17/2026