Glossary

The time it takes for plasma concentration to fall by exactly 50%.

Fraction of an administered dose that reaches systemic circulation unchanged.

A theoretical volume that relates the total amount of drug in the body to its plasma concentration.

The volume of plasma from which a drug is completely removed per unit time.

The highest plasma drug concentration reached after a single dose.

The time after dosing at which plasma concentration reaches its maximum.

The total drug exposure over time, measured as the integral of the concentration–time curve.

The first-order rate constant describing how quickly a drug is absorbed from the site of administration.

The first-order rate constant describing how quickly drug is removed from the body.

Metabolism of a drug in the gut wall or liver before it reaches systemic circulation, reducing effective dose.

The extent to which drug molecules reversibly bind to plasma proteins; only free (unbound) drug is pharmacologically active.

A simplified PK model treating the body as a single homogeneous compartment from which drug is eliminated.

The mass of one mole (6.022 × 10²³ molecules) of a substance, expressed in g/mol.

The fraction of a salt or ester formulation that is the active parent compound by mass.

A notation listing the type and number of each atom in a molecule (e.g. C₁₃H₁₈O₂ for ibuprofen).

One of two non-superimposable mirror-image forms of a chiral molecule; they may differ in biological activity.

An equal mixture of both enantiomers of a chiral compound, often the form used in standard formulations.

International Nonproprietary Name — the official generic name assigned by WHO to identify a pharmaceutical substance.

A unique numerical identifier assigned by the Chemical Abstracts Service to every chemical substance.

Anatomical Therapeutic Chemical classification code — a WHO system that classifies drugs by organ system, therapeutic use, and chemical structure.

RxNorm Concept Unique Identifier — a stable numeric code from the NLM identifying drug concepts regardless of brand or manufacturer.

National Drug Code — a unique 10- or 11-digit US identifier for a specific drug product, labeller, and package size.

Non-Steroidal Anti-Inflammatory Drug — a class that inhibits cyclooxygenase (COX) enzymes to reduce pain, fever, and inflammation.

A drug that blocks cyclooxygenase enzymes (COX-1 and/or COX-2), reducing prostaglandin synthesis.

An indicator of how recently a data point on this site was verified against primary sources.

A pharmacokinetic parameter displayed on a drug page — marked as measured, modelled, or derived, with a source and date.