APC Intern Written Exam key terms

The fraction of an administered dose of unchanged drug that reaches the systemic circulation. Intravenous dosing is defined as complete, while oral dosing is reduced by incomplete absorption and first-pass liver metabolism.

Breakdown of an orally absorbed drug in the intestinal wall or liver before it enters general circulation. It lowers the amount of active drug reaching the body and explains why oral doses often exceed intravenous doses.

A calculated apparent space showing how widely a drug spreads from plasma into body tissues. A large value suggests extensive tissue uptake; a small value suggests the drug stays mostly within the bloodstream.

The volume of plasma from which a drug is completely removed per unit time. Total clearance is the sum of renal, hepatic, and other elimination routes and determines the maintenance dose rate needed to hold steady levels.

The time required for the plasma concentration of a drug to fall by half during elimination. It guides dosing intervals and predicts how long a drug persists after stopping therapy, roughly four to five half-lives for near-complete removal.

The condition in which drug intake equals elimination, so plasma concentrations remain stable between doses. It is generally reached after about four to five half-lives of regular dosing and is the target for therapeutic drug monitoring.

An initial larger dose given to reach therapeutic plasma concentrations quickly rather than waiting several half-lives. It is calculated from the volume of distribution and target concentration, not from clearance.

The regular dose given to replace drug eliminated since the previous dose and keep concentrations at steady state. It is determined by clearance, the desired concentration, and the dosing interval.

A ratio comparing the dose producing toxicity with the dose producing therapeutic effect. A narrow index means effective and harmful concentrations are close, so such drugs need careful dosing and often therapeutic drug monitoring.

Measuring plasma drug concentrations at defined times to individualize dosing for drugs with narrow therapeutic ranges or unpredictable kinetics. Results are interpreted alongside clinical response, timing of the sample, and patient factors.

A drug that binds a receptor and activates it to produce a biological response. Full agonists produce maximal effect, while partial agonists produce a smaller response even when all receptors are occupied.

A drug that binds a receptor without activating it and blocks the action of agonists. Competitive antagonists can be overcome by more agonist, whereas non-competitive antagonists reduce the maximal achievable response.

A protein molecule, often on a cell surface or inside the cell, that binds a drug or natural messenger and triggers a cellular response. Receptor type determines the drug's selectivity, potency, and downstream effects.

The study of what a drug does to the body, including receptor binding, signal transduction, and the resulting therapeutic or toxic effects. It relates drug concentration at the site of action to the intensity of response.

The study of what the body does to a drug, described by absorption, distribution, metabolism, and excretion. These processes determine how quickly and for how long a drug acts.

A harmful or unintended response to a medicine used at normal doses. Reactions may be predictable and dose-related or unpredictable and immune-mediated, and suspected serious cases must be reported to regulators.

The science of detecting, assessing, and preventing adverse effects or other drug-related problems after medicines are marketed. It relies on spontaneous reporting, signal evaluation, and regulatory action such as labeling changes.

A situation in which a medicine should not be used because the risk of harm clearly outweighs any likely benefit. Absolute contraindications forbid use; relative ones require weighing alternatives and added caution.

A condition or patient factor that calls for careful monitoring, dose adjustment, or selection of an alternative rather than outright avoidance of a medicine. Warnings of this kind appear in product information and clinical references.

An alteration in the effect of one medicine caused by another drug, food, drink, or herbal product. Interactions may change absorption, metabolism, protein binding, or the pharmacological response itself.

A large family of liver enzymes that oxidize many drugs. Individual isoenzymes can be inhibited or induced by other medicines, altering blood levels and either causing toxicity or loss of efficacy.

Increased production or activity of drug-metabolizing enzymes after repeated exposure to a substance. It speeds clearance of affected drugs, often lowering their effect and sometimes taking days to develop or resolve.

Reduced activity of drug-metabolizing enzymes caused by another substance. It slows clearance of affected drugs, raising plasma levels and the risk of toxicity, and usually occurs faster than induction.

An inactive compound converted in the body into an active drug, usually by liver enzymes. This design can improve absorption, taste, or targeting, but efficacy depends on the patient's ability to activate it.

A medicine compounded to meet an individual patient's needs when no suitable licensed product exists, for example a liquid for a child who cannot swallow tablets. It requires documented formulas, risk assessment, and appropriate labeling.

A written, approved set of step-by-step instructions describing how a routine task must be performed. In pharmacy it supports consistency, training, and audit trails for activities such as dispensing, compounding, and cleaning.

The quality system ensuring medicinal products are consistently produced and controlled to appropriate standards. It covers premises, equipment, personnel, documentation, and quality control testing throughout production.

The total set of planned activities and systems that ensure a product or service meets defined quality requirements. It is proactive, covering procedures, training, audits, and documentation rather than only final testing.

A patient's voluntary agreement to a treatment or service after receiving and understanding relevant information about benefits, risks, and alternatives. It requires capacity, adequate disclosure, and freedom from coercion.

The professional obligation to protect patient information from unauthorized disclosure. It may be overridden only in specific circumstances defined by law or when there is a serious risk to others.

Legal rules governing how personal information, including health data, may be collected, stored, used, and shared. Organizations must keep records secure, limit access to those who need it, and honor individual rights.

The legal and ethical obligation to act in a patient's best interests and avoid foreseeable harm. It underpins standards such as accurate dispensing, adequate counseling, and appropriate referral when concerns arise.

A failure to provide the standard of care expected of a reasonably competent practitioner, resulting in harm. It requires a duty of care, a breach of that duty, causation, and actual damage.

The level and quality of practice expected from a competent professional in similar circumstances, shaped by guidelines, law, and accepted practice. Departing from it may be used as evidence in negligence claims.

A national system for reporting suspected adverse drug reactions and defective medicines to the regulator. Reports from health professionals and patients contribute to safety signals and regulatory decisions.

The largest amount of a medicine recommended for a patient in a given period, usually stated in product information. Exceeding it increases the risk of toxicity, though clinical judgment may justify exceptions with documentation.

The arithmetic process of determining the amount of drug to administer from a prescription, patient weight or body surface area, and available product strength. It requires unit conversion and careful checking.

Adjusting a calculated number to a practical value that can be measured with available equipment. In pharmacy it must be clinically appropriate, avoiding significant underdosing or overdosing of potent medicines.