To all pharmacists and Pharmacy students: What is the difference between the USP and the National Formulary?

Question

If all compounds listed in both are considered official, why have two different compilations and not just one?

Answer 1

it used to be two different things. Kinda like Ringling Brothers Barnum and Bailey circus.

Answer 2

The United States Pharmacopeia is a compendium of quality control tests for drugs and excipients to be introduced into a medicinal formulation. It is published every year [1] by the United States Pharmacopoeial Convention. It forms the basis of enforcement actions by the U.S. Food and Drug Administration and the U.S. Drug Enforcement Administration and is the official pharmacopoeia of the U.S.A. and several other nations. Therefore, in case of a dispute those methods for, amongst others, identification, assay and purity determination of a drug substance or excipient which are stated in the USP will be the legally binding ones.
A National Formulary is a manual containing a list of medicines that are approved for prescription throughout the country, indicating which products are interchangeable. It includes key information on the composition, description, selection, prescribing, dispensing and administration of medicines. Those drugs considered less suitable for prescribing are clearly identified.
In some countries, there are regional or provincial formularies instead of or in addition to the national formulary.
By the turn of the millennium, 156 countries had national or provincial essential medicines lists and 135 countries had national treatment guidelines and/or formulary manuals.
Please see the webpages for more details on United States Pharmacopea and National Formulary.