(1) Physicians and Dentists. A physician or a dentist, in good faith and in the course of his professional practice only, may prescribe, administer, and dispense narcotic drugs, or he may cause the same to be administered by a nurse or intern under his direction and supervision.
(2) Veterinarians. A veterinarian, in good faith and in the course of his professional practice only, and not for use by a human being, may prescribe, administer, and dispense narcotic drugs, and he may cause them to be administered by an assistant or orderly under his direction and supervision.
(3) Return of Unused Drugs. Any person who has obtained from a physician, dentist, or veterinarian any narcotic drug for administration to a patient during the absence of such physician, dentist, or veterinarian, shall return to such physician, dentist, or veterinarian any unused portion of such drug, when it is no longer required by the patient.