It shall be unlawful for any person to sell, dispense, or give away any preparation containing opium except upon a valid prescription of a physician, dentist, or veterinarian. Exempt from this prohibition are:sales made to registered practitioners of pharmacy, medicine, dentistry, or veterinary medicine; or sales made by any manufacturer, wholesale druggist, or licensed pharmacist to a hospital or institution operating a dispensary in which a practitioner licensed by law to administer dangerous drugs is in charge. City Code, 1976/83, art. 19, §22(2) Ord. 69-524