Mo. Rev. Stat. § 338.198: Pharmacist may fill prescription forwarded by authorized agent.

Other provisions of law to the contrary notwithstanding, a pharmacist may fill a physician's prescription or the prescription of an advanced practice nurse working under a collaborative practice arrangement with a physician, when it is forwarded to the pharmacist by a registered professional nurse or registered physician's assistant or other authorized agent. The written collaborative practice arrangement shall specifically state that the registered professional nurse or registered physician assistant is permitted to authorize a pharmacist to fill a prescription on behalf of the physician.