Can a registered nurse inject Botox or filler in Missouri?

Short answer
Yes — an RN may administer injectables under a written collaborative practice arrangement with a physician that delegates drug administration, provided it is within the RN's scope, skill and training; only an APRN may be delegated authority to prescribe.

An advanced practice registered nurse in Missouri is a person licensed under the nursing chapter to practice advanced practice nursing as a certified clinical nurse specialist, certified nurse midwife, certified nurse practitioner or certified registered nurse anesthetist. Prescribing runs through the written arrangement on the face of these claims: a collaborative practice arrangement MAY delegate to an APRN the authority to administer, dispense or prescribe drugs and provide treatment, and may delegate authority over controlled substances in Schedules III, IV and V and Schedule II hydrocodone. The delegation runs through the written arrangement described in the supervision section of this reference; whether any independent route exists elsewhere in the nursing chapter is not surveyed by these claims. Physician assistants are bounded differently again: the statute enumerates their scope of practice as consisting ONLY of nine listed services and procedures, and says a physician assistant may not prescribe any drug, medicine, device or therapy except pursuant to a collaborative practice arrangement.