Reference
Glossary
Short, plain-English definitions. The same text appears as tooltips across the site.
- 503A compounding
- Pharmacy compounding of a medication for an individual patient under a prescription. A substance must be eligible before it can legally be compounded.
- Adverse effectSide effect
- An unwanted effect of a substance, ranging from mild to serious.
- Agonist
- A molecule that binds a receptor and activates it, mimicking the body's own signal.
- Bulk drug substance503A bulks list
- An active ingredient FDA has evaluated for use in compounding. Being on the list is not the same as being an approved drug.
- Category 2
- FDA's interim list of nominated compounding substances that raise significant safety risks and may not be compounded under enforcement discretion.
- Concentration
- The amount of substance per unit of volume — for example, milligrams per millilitre (mg/mL).
- Contraindication
- A situation in which a substance should not be used because the risk clearly outweighs any benefit.
- FDA approval
- A determination by the U.S. Food and Drug Administration that a specific product is safe and effective for a specific use, based on clinical trial evidence.
- Half-life
- The time it takes for the amount of a substance in the body to fall by half.
- In vitro
- In the laboratory, in cells or tissue outside a living organism. Shows what is possible, not what happens in a body.
- In vivo
- In a living organism — an animal or a person.
- Indication
- The specific condition a drug is approved to treat.
- International UnitIU
- A measure of biological activity defined separately for each substance. IU cannot be converted to milligrams without substance-specific data.
- Mechanism of actionMoA
- The specific biological interaction through which a substance produces its effect.
- PCACPharmacy Compounding Advisory Committee
- An FDA advisory committee that votes on whether substances should be added to the compounding bulks list. Its votes are recommendations, not decisions.
- Peptide
- A short chain of amino acids — usually fewer than about 50 — joined by peptide bonds. Longer chains fold into proteins.
- PharmacokineticsPK
- How a substance is absorbed, distributed, broken down and removed by the body.
- Phase 1
- First human trials, usually small, focused on safety and how the body handles a substance.
- Phase 2
- Mid-size trials looking for early signs of effect and the right amount to study further.
- Phase 3
- Large trials comparing the treatment against standard care or placebo; the basis for most approvals.
- Placebo
- An inactive comparison treatment used to measure how much of an effect is due to the treatment itself.
- Randomised controlled trialRCT
- A study that randomly assigns people to receive the treatment or a comparison, so differences can be attributed to the treatment.
- Receptor
- A protein on or inside a cell that a molecule can bind to, triggering a response in the cell.
- Reconstitution
- Dissolving a dry powder in a liquid to make a solution. The final volume, not the liquid added, sets the concentration.
- U-100 syringe
- A syringe marked in insulin units where 100 units equal 1 mL. The markings measure volume, not the amount of any other drug.