Cal. Business and Professions Code § 4052.10

(a) A pharmacist may dispense a Schedule II controlled substance, as listed in Section 11055 of the Health and Safety Code, as a partial fill if requested by the patient or the prescriber. (b) If a pharmacist dispenses a partial fill on a prescription pursuant to this section, the pharmacy shall retain the original prescription, with a notation of how much of the prescription has been filled, until the prescription has been fully dispensed. The total quantity dispensed shall not exceed the total quantity prescribed. (c) Subsequent fills, until the original prescription is completely dispensed, shall occur at the pharmacy where the original prescription was partially filled. The full prescription shall be dispensed not more than 30 days after the date on which the prescription was written. Thirty-one days after the date on which the prescription was written, the prescription shall expire and no more of the drug shall be dispensed without a subsequent prescription. (d) The pharmacist shall record in the state prescription drug monitoring program only the actual amounts of the drug dispensed. (e) The pharmacist shall record the date and amount of each partial fill in a readily retrievable form and on the original prescription, and shall include the initials of the pharmacist who dispensed each partial fill. (f) A pharmacist may charge a professional dispensing fee to cover the actual supply and labor costs associated with dispensing each partial fill associated with the original prescription. (g) This section shall not be construed to limit the authority of the Department of Managed Health Care, pursuant to Chapter 2.2 (commencing with Section 1340) of Division 2 of the Health and Safety Code. (h) This section is not intended to conflict with or supersede any other requirement established for the prescription of a Schedule II controlled substance. (i) For purposes of this section, the following definitions apply: (1) “Original prescription” means the prescription presented by the patient to the pharmacy or submitted electronically to the pharmacy. (2) “Partial fill” means a part of a prescription filled that is of a quantity less than the entire prescription. (j) This section shall become operative on July 1, 2018.