CMCC External Pharmacist Exam key terms

The fraction of an administered dose of unchanged drug that reaches systemic circulation. Intravenous dosing is defined as 100%; oral bioavailability is reduced by incomplete absorption and first-pass metabolism.

Presystemic elimination of an orally absorbed drug by gut wall and liver enzymes before it reaches systemic circulation. It lowers oral bioavailability and can be saturated, causing disproportionate increases in plasma concentration with dose escalation.

An apparent volume relating the amount of drug in the body to its plasma concentration. A large Vd indicates extensive tissue distribution; Vd is used to calculate loading doses.

The volume of plasma from which drug is completely removed per unit time. Total clearance equals the sum of hepatic, renal, and other clearances and determines the maintenance dose rate needed to sustain a target concentration.

The time required for plasma drug concentration to fall by half during first-order elimination. It governs how quickly steady state is reached (about four to five half-lives) and how long a drug persists after stopping.

The condition in which drug input rate equals elimination rate, so plasma concentrations fluctuate within a constant range. It is generally attained after four to five elimination half-lives of constant dosing.

Elimination at a constant rate independent of drug concentration, because metabolic or transport capacity is saturated. Small dose increases can then produce large, unpredictable rises in plasma levels, as seen with phenytoin and ethanol.

Elimination in which a constant fraction of the drug is removed per unit time, so the rate is proportional to plasma concentration. Most drugs follow this pattern, giving a fixed half-life regardless of dose.

The integral of plasma concentration versus time after a dose, reflecting total systemic exposure. AUC is used to assess bioavailability and bioequivalence and to estimate clearance when dose is known.

The demonstration that two pharmaceutically equivalent products have comparable rate and extent of absorption, typically judged by AUC and peak concentration falling within accepted confidence limits. It supports interchangeability of generic and reference products.

An initial larger dose given to rapidly achieve a target plasma concentration when immediate effect is needed. It is calculated from volume of distribution and desired concentration, not from clearance.

The dose given repeatedly to keep plasma concentration at steady state by balancing ongoing elimination. It is determined by clearance, desired concentration, and dosing interval, and is independent of volume of distribution.

Measurement of plasma drug concentrations to individualize dosing for drugs with narrow therapeutic ranges, poor concentration-effect correlation, or high interpatient variability. Sampling time relative to the dose must be recorded for interpretation.

A ratio comparing the dose producing toxicity with the dose producing therapeutic effect. A low index means the effective and toxic ranges are close, requiring careful dosing and monitoring.

A medicine whose effective and toxic concentrations differ only slightly, so small changes in dose, formulation, or interactions can cause harm or loss of effect. Examples include warfarin, digoxin, lithium, and phenytoin.

The study of what a drug does to the body, including receptor binding, signal transduction, and the resulting concentration-response relationship. It explains potency, efficacy, and the mechanism of therapeutic and toxic effects.

The study of what the body does to a drug, described by absorption, distribution, metabolism, and excretion. These processes determine the time course of drug concentration at the site of action.

A ligand that binds a receptor and activates it to produce a biological response. Full agonists produce maximal response; partial agonists produce submaximal response even at full receptor occupancy.

A ligand that binds a receptor without activating it and blocks the effect of agonists. Competitive antagonists are surmountable by raising agonist concentration; noncompetitive antagonists are not.

A drug that binds and activates a receptor but produces less than the maximal possible response, even when all receptors are occupied. It can act as a functional antagonist when a full agonist is present.

An inactive or less active chemical derivative that is converted in the body to the active drug, usually to improve absorption, stability, or targeting. Examples include enalapril, valacyclovir, and codeine.

Enzymatic conversion of drugs, mainly in the liver, into more water-soluble or more active compounds. Phase I reactions (oxidation, reduction, hydrolysis) often precede Phase II conjugation reactions.

A family of heme-containing monooxygenases responsible for most Phase I drug oxidation. Individual isoforms such as CYP3A4, CYP2D6, and CYP2C9 differ in substrate specificity and genetic variability, shaping interactions and response.

Increased synthesis or activity of drug-metabolizing enzymes after repeated exposure to an inducer, raising clearance and lowering substrate concentrations. Effects develop over days to weeks and resolve slowly after the inducer stops.

Reduction of metabolic enzyme activity by a competing or irreversible inhibitor, decreasing clearance and raising substrate concentrations. Onset is usually rapid and can precipitate toxicity for narrow-index drugs.

A change in a drug's effect caused by another drug, food, or supplement, acting through pharmacokinetic or pharmacodynamic mechanisms. Clinically significant interactions alter efficacy or toxicity and may require dose adjustment or avoidance.

A harmful or unintended response to a medicine at normal doses. Reactions are classified by mechanism, for example dose-related (Type A) or idiosyncratic (Type B), and suspected serious reactions must be reported.

The science of detecting, assessing, understanding, and preventing adverse effects or other drug-related problems. It relies on spontaneous reporting, signal detection, and regulatory action to protect public safety.

The condition in which two products contain the same active ingredient in the same amount and dosage form and meet the same compendial standards. It does not by itself establish bioequivalence or therapeutic interchangeability.

A product marketed after the reference product's patent or exclusivity expires, containing the same active substance and shown to be bioequivalent. It must meet the same quality, safety, and efficacy standards.

An inactive ingredient included in a dosage form to aid manufacture, stability, or delivery. Excipients can affect drug release and can cause adverse reactions, such as lactose intolerance or hypersensitivity to dyes.

A dosage form engineered to release drug slowly over an extended period, reducing dosing frequency and smoothing plasma fluctuations. Such products must not be crushed or chewed unless specifically labeled, to avoid dose dumping.

A written or electronic order from an authorized prescriber for dispensing a medicine, containing patient, drug, dose, directions, and prescriber details. Pharmacists must verify legality, completeness, and clinical appropriateness before dispensing.

A medicine legally restricted to supply on a valid prescription from a licensed prescriber. Its classification reflects the need for medical supervision because of toxicity, indication, or resistance concerns.

A medicine approved for sale without a prescription for self-treatment of minor conditions. Availability depends on criteria such as low toxicity, clear labeling, and limited need for medical supervision.

A deviation during the dispensing process, such as wrong drug, strength, or label, that reaches or could reach the patient. Reporting and root-cause analysis are used to prevent recurrence.

Any preventable event that may cause or lead to inappropriate medication use or patient harm, occurring at prescribing, dispensing, administration, or monitoring stages. Errors are distinct from adverse drug reactions, which may occur without error.

Structured communication with a patient or caregiver about correct use, expected effects, precautions, and storage of a medicine. It improves adherence and helps detect and prevent drug-related problems.

The extent to which a patient takes medication as prescribed, including timing, dose, and duration. It is influenced by regimen complexity, side effects, cost, and health beliefs, and can be supported by counseling and reminders.

The study of medicinal substances of natural origin, including plant, fungal, and animal sources. It covers identification, isolation of active constituents, standardization, and quality control of crude drugs and extracts.

A naturally occurring nitrogen-containing basic compound found in plants and fungi, often pharmacologically potent. Examples include morphine, quinine, caffeine, and vincristine.

A plant preparation adjusted so that a defined marker compound or group is present at a stated concentration. Standardization supports batch-to-batch consistency but does not guarantee clinical equivalence.

A clinically relevant change in drug effect caused by a botanical product, often through enzyme induction or inhibition. St John's wort, for example, induces CYP3A4 and can reduce concentrations of many drugs.

A system of quality assurance ensuring that medicinal products are consistently produced and controlled according to quality standards. It covers premises, personnel, documentation, validation, and quality control testing.

Regulatory approval permitting a medicine to be sold for specified indications, based on evidence of quality, safety, and efficacy. Holders must comply with post-approval obligations such as safety reporting and variations.

A patient's voluntary agreement to a treatment or procedure after receiving and understanding relevant information about benefits, risks, and alternatives. It is a core ethical and legal requirement in clinical practice and research.