A drug or device shall be deemed to be misbranded if it is a drug which by label provides, or which the federal act or any applicable law requires by label to provide, in effect, that it shall be used only upon the prescription of a physician, dentist, or veterinarian, unless it is dispensed at retail on a written prescription signed by a physician, dentist, or veterinarian, who is licensed by law to administer such a drug.
RCW 69.04.540