1.  A physician assistant with a certificate of controlled substance prescriptive authority as provided in this section may prescribe any controlled substance listed in Schedule III, IV, or V of section 195.017, and may have restricted authority in Schedule II, when delegated the authority to prescribe controlled substances in a collaborative practice arrangement.  Such authority shall be listed on the collaborating physician form on file with the state board of healing arts.  The collaborating physician shall maintain the right to limit a specific scheduled drug or scheduled drug category that the physician assistant is permitted to prescribe.  Any limitations shall be listed on the collaborating physician form.  Prescriptions for Schedule II medications prescribed by a physician assistant with authority to prescribe delegated in a collaborative practice arrangement are restricted to only those medications containing hydrocodone.  Physician assistants shall not prescribe controlled substances for themselves or members of their families.  Schedule III controlled substances and Schedule II - hydrocodone prescriptions shall be limited to a five-day supply without refill, except that buprenorphine may be prescribed for up to a thirty-day supply without refill for patients receiving medication-assisted treatment for substance use disorders under the direction of the collaborating physician.  Physician assistants who are authorized to prescribe controlled substances under this section shall register with the federal Drug Enforcement Administration and the state bureau of narcotics and dangerous drugs, and shall include the Drug Enforcement Administration registration number on prescriptions for controlled substances. see full law