Compounding glossary
Definitions for the vocabulary that appears on pharmacy labels, certificates of analysis, and regulatory paperwork. Terms are described in plain language; where a definition touches a regulatory standard, the standard itself governs.
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- 503A pharmacy
- A traditional compounding pharmacy operating under section 503A of the Federal Food, Drug, and Cosmetic Act. It compounds for an identified patient pursuant to a valid prescription, and is regulated primarily by its state board of pharmacy.
- 503B outsourcing facility
- A facility registered with the FDA under section 503B that may compound in batches without patient-specific prescriptions. It is subject to cGMP requirements and direct FDA inspection.
A
- Active pharmaceutical ingredient (API)
- The component of a preparation that carries the intended pharmacological activity, as distinct from the excipients around it.
- Adverse event
- Any untoward medical occurrence associated with the use of a preparation, whether or not a causal relationship has been established.
- Aliquot
- A measured portion drawn from a larger volume, typically for dilution or for dividing a preparation into smaller quantities.
- Ampoule
- A sealed single-use glass container that is broken open at the neck. It has no stopper and cannot be re-entered, so any unused contents are discarded.
- Anteroom
- The classified space adjacent to a cleanroom where garbing, hand hygiene, and supply staging occur before entering the compounding area.
- Aseptic technique
- The set of practices used to prevent microbial contamination of a sterile product during handling — hand hygiene, surface disinfection, sterile supplies, and controlled movement within the work area.
B
- Bacteriostatic water for injection
- Sterile water containing an antimicrobial preservative, commonly benzyl alcohol, which inhibits microbial growth and permits repeated entry into a vial.
- Beyond-use date (BUD)
- The date or time after which a compounded preparation must not be used. Assigned by the compounding pharmacy based on stability and sterility risk — distinct from a manufacturer's expiration date.
- Bevel
- The angled cutting face at the tip of a needle. Orientation of the bevel affects both penetration and the likelihood of coring a stopper.
- Buffer
- A component included to hold a preparation's pH within a range where the active ingredient remains stable and the solution is tolerable on administration.
C
- Certificate of analysis (CoA)
- A document issued by a manufacturer or testing laboratory recording the analytical results for a specific lot — identity, purity, potency, and any tests for contaminants.
- cGMP
- Current Good Manufacturing Practice. The FDA-enforced quality framework covering facilities, equipment, process controls, and documentation for pharmaceutical manufacturing. It applies to 503B outsourcing facilities.
- Cleanroom
- A controlled environment with defined limits on airborne particulates and microbial contamination, used for compounding sterile preparations.
- Cold chain
- The unbroken sequence of temperature-controlled storage and transport that keeps a product within its required range from the pharmacy to the point of use.
- Compounding
- The preparation, mixing, packaging, or labeling of a drug in response to a prescription or, for outsourcing facilities, in anticipation of prescriptions.
- Concentration
- The amount of drug substance per unit volume of solution, usually expressed as mg/mL or mcg/mL. It follows directly from the diluent volume added.
- Coring
- The dislodging of a fragment of rubber stopper by a needle, which then enters the vial as particulate contamination. Reduced by centre entry, bevel-up technique, and slight rotation on insertion.
D
- Dead space
- The residual volume held in the needle hub and syringe tip after the plunger is fully depressed. It becomes proportionally significant with very small draws.
- Diluent
- The sterile fluid added to a lyophilized or concentrated preparation to bring it into solution at a usable concentration.
E
- Endotoxin
- A heat-stable component of the outer membrane of Gram-negative bacteria that can provoke a pyrogenic response even after the organisms themselves are killed. Tested for separately from sterility.
- Excipient
- Any component of a preparation other than the active ingredient — buffers, bulking agents, stabilisers, tonicity modifiers, preservatives.
- Expiration date
- The date established by a manufacturer through stability testing, after which an unopened product in its original container should not be used.
F
- Filter needle
- A needle incorporating a filter membrane, used when drawing from an ampoule to prevent glass fragments from entering the syringe.
H
- Hypotonic / hypertonic / isotonic
- Descriptions of a solution's osmotic pressure relative to blood. Isotonic solutions match it; hypotonic and hypertonic solutions fall below and above it respectively.
I
- International unit (IU)
- A measure of biological activity defined separately for each substance against an international reference standard. There is no universal conversion between IU and mass.
L
- Lot number
- The identifier assigned to a specific production batch, enabling traceability from a dispensed vial back to its manufacturing and testing records.
- Luer lock / luer slip
- Two syringe tip standards. A luer lock threads onto the needle hub and secures it; a luer slip relies on friction fit alone.
- Lyophilization
- Freeze-drying. The preparation is frozen and water is removed by sublimation under vacuum, leaving a porous dry cake that is far more stable than the solution was.
- Lyophilized cake
- The solid porous plug remaining in a vial after freeze-drying. Its appearance — intact, collapsed, or shrunken — is part of visual inspection.
M
- Multi-dose vial
- A vial intended for more than one entry, which requires an antimicrobial preservative and a defined in-use period after first puncture.
O
- Osmolality
- A measure of solute concentration in a solution, relevant to tolerability on injection and to compatibility with the chosen diluent.
P
- Parenteral
- Administered by a route other than the digestive tract — most commonly intravenous, intramuscular, or subcutaneous injection.
- Particulate matter
- Undissolved, mobile solid material in a solution. Its presence on visual inspection is a criterion for discarding a preparation.
- Peptide
- A chain of amino acids shorter than a protein. Peptides are generally sensitive to heat, agitation, freeze-thaw cycling, and pH change, which shapes how they are handled.
- Potency
- The measured strength of a preparation relative to its labeled strength, established by assay and reported on the certificate of analysis.
- Preservative
- An excipient added to inhibit microbial growth, permitting repeated entry into a multi-dose container. Benzyl alcohol is the most common in injectable diluents.
- Primary engineering control (PEC)
- The device providing an ISO Class 5 air environment for sterile compounding — for example a laminar airflow workbench, biological safety cabinet, or isolator.
R
- Reconstitution
- Adding a measured volume of diluent to a lyophilized or dry preparation to produce a solution of known concentration.
S
- Sharps container
- A rigid, puncture-resistant container for the disposal of needles, syringes, and other sharp waste, handled under regulated medical waste procedures.
- Single-dose vial
- A vial without an antimicrobial preservative, intended for one entry and one patient. Residual contents are discarded, however much remains.
- Sodium chloride 0.9%
- Isotonic saline. Available as plain (unpreserved, single-use) or bacteriostatic (preserved). Not universally interchangeable with water as a diluent.
- Sterile water for injection
- Water that has been sterilised and contains no preservative or additive. Because nothing inhibits microbial growth, a vial reconstituted with it is treated as single-use.
- Sterility
- The absence of viable microorganisms. For compounded sterile preparations it is assured through validated process controls and testing, not inferred from appearance.
- Sublimation
- The transition of a substance directly from solid to vapour without passing through a liquid phase — the mechanism by which water is removed during lyophilization.
T
- Titration
- Stepwise adjustment of an administered amount over time, following a schedule set by the prescriber.
U
- USP <795>
- The United States Pharmacopeia chapter governing non-sterile compounding, covering facilities, components, process, and beyond-use dating.
- USP <797>
- The USP chapter governing sterile compounding, including environmental controls, personnel training and testing, and beyond-use date limits by risk category.
- USP <800>
- The USP chapter covering the safe handling of hazardous drugs, addressing containment, personal protective equipment, and facility design to protect personnel.
- U-100 / U-50 / U-40
- Insulin syringe calibration standards marking 100, 50, and 40 units per millilitre respectively. The designation determines what volume a single graduation represents.
V
- Vial
- A sealed container closed with an elastomeric stopper and a metal crimp, entered by needle through the stopper rather than by removing a cap.
- Visual inspection
- Examination of a solution against light and dark backgrounds for clarity, colour, and particulates before use.
Missing a term you expected to find? The FAQ covers several operational questions that do not reduce to a single definition.