503A Compounding

Section 503A of the Federal Food, Drug, and Cosmetic Act exempts a drug compounded by a licensed pharmacist or physician, for an identified individual patient with a valid prescription, from three requirements: approval under section 505, current good manufacturing practice, and adequate directions for use. It exempts nobody from the adulteration and misbranding provisions. Routine oversight sits with state boards of pharmacy rather than with FDA.

The conditions are specific. A bulk substance qualifies only if it has a USP or NF monograph, is a component of an approved drug, or sits on the 503A bulks list, and the preparation may not be essentially a copy of a commercially available product unless that product is on FDA's shortage list. Compounded semaglutide and tirzepatide were produced at scale under exactly that shortage carve-out, and the wind-down deadlines FDA set once it declared those shortages resolved show how quickly the position moves; current status belongs to FDA's shortage database, not to a secondary account.

What this changes is where assurance comes from. Nobody has reviewed a 503A preparation's potency, impurity profile, container stability or labelling, and its beyond-use date is assigned from a USP chapter 797 category rule rather than from stability data on that formulation. Responsibility rests with the prescriber and pharmacist, which is easier to justify for a patient who genuinely cannot use the approved product than for one choosing on price.

The phrase to distrust is FDA-registered pharmacy, which means an address on a list and nothing about the product. Two errors recur: treating semaglutide sodium or acetate as interchangeable with the approved base, when a salt of a different active moiety falls outside what 503A permits, and adding a token ingredient so a formulation can be argued not to be essentially a copy.