(a) Except as provided in subdivision (b), any narcotic controlled substance employed in treating a person with substance use disorder for addiction shall be administered by:

1. (1) A physician and surgeon.
2. (2) A registered nurse acting under the instruction of a physician and surgeon.
3. (3) A physician assistant licensed pursuant to Chapter 7.7 (commencing with Section 3500) of Division 2 of the Business and Professions Code acting under the patient-specific authority of their physician and surgeon.

(b) When acting under the direction of a physician and surgeon, the following persons may administer a narcotic controlled substance in the treatment of a person with substance use disorder for addiction to a controlled substance:

1. (1) A psychiatric technician licensed pursuant to Chapter 10 (commencing with Section 4500) of Division 2 of the Business and Professions Code.
2. (2) A vocational nurse licensed pursuant to Chapter 6.5 (commencing with Section 2840) of Division 2 of the Business and Professions Code.
3. (3) A pharmacist licensed pursuant to Chapter 9 (commencing with Section 4000) of Division 2 of the Business and Professions Code.