Primary engineering control (PEC)
The hood or isolator where sterile preparations are made, supplying ISO Class 5 air.
Learn more: Sterile Compounding (USP <797>)#
503A pharmacy
A licensed pharmacy that compounds medications for individual patients against a prescription, under section 503A of the FD&C Act and state board oversight.
Learn more: 503A vs. 503B503B outsourcing facility
A facility registered with the FDA under section 503B that can compound larger batches, with or without patient-specific prescriptions, and must follow cGMP.
Learn more: 503A vs. 503BA
Active pharmaceutical ingredient (API)
The ingredient in a medication that produces its intended effect. In compounding it's often called a bulk drug substance.
Adverse event
An unwanted or harmful reaction after taking a medication. Report it to your prescriber and pharmacy; it can also be reported to the FDA through MedWatch.
Anteroom
The room where staff wash and put on garb before entering the cleanroom buffer room. Usually ISO Class 8.
Learn more: Sterile Compounding (USP <797>)Anticipatory compounding
Preparing a limited amount of a compounded medication before receiving a prescription, based on the pharmacy's history of prescriptions for it.
Learn more: 503A vs. 503BAseptic technique
Methods used in sterile compounding to keep microorganisms out of a preparation, such as never touching critical sites.
Learn more: Sterile Compounding (USP <797>)B
Beyond-use date (BUD)
The date or time after which a compounded preparation should not be used. It's set by USP rules or stability data and is printed on the label.
Buffer room
The cleanroom area that houses the primary engineering control, kept at ISO Class 7.
Learn more: Sterile Compounding (USP <797>)Bulk drug substance
A raw active ingredient used to compound a medication. Federal law limits which bulk substances 503A and 503B compounders may use.
Learn more: 503A vs. 503BC
Certificate of analysis (COA)
A document from an ingredient supplier showing that a specific lot was tested and meets its specifications.
Learn more: Non-Sterile Compounding (USP <795>)cGMP
Current Good Manufacturing Practice: the FDA's quality rules for drug manufacturing, which 503B outsourcing facilities must follow.
Learn more: 503A vs. 503BCleanroom suite
A set of rooms, usually an anteroom and a buffer room, built and monitored to keep airborne particles low for sterile compounding.
Learn more: Sterile Compounding (USP <797>)Compounded nonsterile preparation (CNSP)
A compounded medication that doesn't need to be sterile, such as a capsule, cream, or oral liquid. Covered by USP <795>.
Learn more: Non-Sterile Compounding (USP <795>)Compounded sterile preparation (CSP)
A compounded medication that must be sterile, such as an injection or eye drop. Covered by USP <797>.
Learn more: Sterile Compounding (USP <797>)Compounding
Combining, mixing, or altering ingredients to create a medication tailored to a patient's needs.
Learn more: What Is a Compounding Pharmacy?Compounding record
The documentation made each time a preparation is compounded: who made it, ingredient lot numbers, and the checks performed.
Learn more: Non-Sterile Compounding (USP <795>)D
Dosage form
The physical form of a medication, such as a capsule, liquid, cream, or injection.
Drug Quality and Security Act (DQSA)
The 2013 federal law that created the 503B outsourcing facility category and updated the rules for compounding.
Learn more: 503A vs. 503BE
Endotoxin
A substance from the outer layer of certain bacteria that can cause fever if injected. Some sterile preparations are tested for it.
Learn more: Sterile Compounding (USP <797>)Environmental monitoring
Regular sampling of air and surfaces in a compounding area to check for microorganisms and particles.
Learn more: Sterile Compounding (USP <797>)Excipient
An inactive ingredient, such as a filler, binder, base, flavor, or preservative.
Expiration date
The date a manufacturer assigns to an FDA-approved product, based on stability studies. Compounded preparations get a beyond-use date instead.
F
FD&C Act
The Federal Food, Drug, and Cosmetic Act, the main federal law for drugs. Sections 503A and 503B cover compounding.
Learn more: 503A vs. 503BFDA-approved drug
A drug the FDA has reviewed for safety and effectiveness before it's marketed. Compounded medications are not FDA-approved.
Learn more: What Is a Compounding Pharmacy?G
Garbing
Putting on protective clothing, such as hair and shoe covers, mask, gown, and gloves, in a set order before compounding.
Learn more: Sterile Compounding (USP <797>)Gloved fingertip test
A test where a compounder's gloved fingertips and thumbs are pressed onto growth media to check aseptic garbing.
Learn more: Sterile Compounding (USP <797>)H
Hazardous drug
A medication that can harm the people who handle it, such as some cancer drugs. Its handling is covered by USP <800>.
HEPA filter
A high-efficiency particulate air filter that removes nearly all airborne particles. Used in hoods and cleanrooms.
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ISO class
A rating of air cleanliness by particle count. Lower numbers are cleaner: ISO 5 in the hood, ISO 7 in the buffer room.
Learn more: Sterile Compounding (USP <797>)L
Lot number
A code that identifies a specific batch of a medication or ingredient, so it can be traced if there's ever a problem.
M
Master formulation record
The written recipe for a compounded preparation: ingredients, amounts, equipment, steps, and beyond-use date.
Learn more: Non-Sterile Compounding (USP <795>)Media-fill test
A test that simulates sterile compounding using a growth medium instead of drug, to check a person's aseptic technique.
Learn more: Sterile Compounding (USP <797>)MedWatch
The FDA's program for reporting side effects and product problems with medications, including compounded ones.
O
P
S
Segregated compounding area (SCA)
A designated space, not a full cleanroom, where only the shortest-dated sterile preparations (Category 1) may be made.
Learn more: Sterile Compounding (USP <797>)State board of pharmacy
The state agency that licenses and inspects pharmacies and pharmacists.
Sterility testing
Laboratory testing to confirm a sterile preparation is free of microorganisms. Required for some sterile preparations.
Learn more: Sterile Compounding (USP <797>)Suspension
A liquid where the medication is spread through the liquid rather than dissolved, so it must be shaken before each dose.
Learn more: Non-Sterile Compounding (USP <795>)T
Troche
A medicated lozenge that dissolves slowly in the mouth.
Learn more: Non-Sterile Compounding (USP <795>)U
USP
The United States Pharmacopeia, a nonprofit that publishes quality standards for medicines, including compounding standards.
USP <795>
The USP chapter with standards for non-sterile compounding.
Learn more: Non-Sterile Compounding (USP <795>)USP <797>
The USP chapter with standards for sterile compounding.
Learn more: Sterile Compounding (USP <797>)USP <800>
The USP chapter with standards for safely handling hazardous drugs.
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Compounding 101
Educational content only. It is not medical advice and does not replace advice from your prescriber or pharmacist. Compounded medications are not FDA-approved and require a valid prescription. Last updated October 2026.
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