NHRA Pharmacist Exam key terms

The fraction of an administered dose of unchanged drug that reaches systemic circulation, expressed as a percentage. Intravenous administration is defined as 100%, and oral values are compared against it.

Presystemic elimination of an orally absorbed drug by gut wall or liver enzymes before it reaches systemic circulation. It lowers oral bioavailability and may make a drug unusable by mouth.

The absence of a significant difference in rate and extent of absorption between two pharmaceutically equivalent products. Regulators usually accept 90% confidence intervals for AUC and Cmax falling within 80 to 125%.

An apparent volume relating the amount of drug in the body to its plasma concentration. Large values suggest extensive tissue uptake; small values suggest confinement to plasma water.

The volume of plasma from which a drug is completely removed per unit time. Total clearance determines the maintenance dose rate needed to sustain a target steady-state concentration.

The time required for plasma concentration to fall by half during elimination. It governs dosing interval selection and the time to reach steady state, roughly four to five half-lives.

The condition in which drug input equals elimination, so plasma concentrations fluctuate around a constant average. It is reached after about four to five elimination half-lives of regular dosing.

An initial larger dose given to rapidly achieve therapeutic plasma concentrations. It is calculated from the target concentration and volume of distribution, not from clearance.

A ratio comparing the dose producing toxicity with the dose producing therapeutic effect. A narrow index means small dose changes can cause harm, so monitoring or careful titration is required.

Measurement of drug concentrations in blood to individualize dosing for drugs with narrow therapeutic indices or unpredictable pharmacokinetics. Timing of sampling relative to the dose is critical.

An inactive chemical derivative converted in the body to the active drug, often to improve absorption or bypass first-pass metabolism. Examples include ester prodrugs hydrolyzed by esterases.

Any inactive ingredient added to a dosage form to serve functions such as filling, binding, disintegrating, preserving, flavoring, or aiding absorption. Excipients must be compatible with the active ingredient and safe by route.

A liquid dosage form in which insoluble solid particles are dispersed in a liquid vehicle. Shaking is required before use, and particle settling and caking are key stability concerns.

A dispersion of one immiscible liquid in another, stabilized by an emulsifying agent. Oil-in-water and water-in-oil types differ in appearance, feel, and suitability for different routes.

A polymer film on a tablet or capsule that resists gastric acid and dissolves in the intestine. It protects acid-labile drugs or the stomach, and such products must not be crushed.

A dosage form designed to release drug gradually over an extended period, reducing dosing frequency and smoothing plasma concentration peaks and troughs. Such forms usually must be swallowed whole.

A drug 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 occupancy.

A drug that binds a receptor without activating it, blocking the effect of agonists. Competitive antagonists can be overcome by more agonist; noncompetitive antagonists cannot.

A cellular protein that binds a signaling molecule or drug and triggers a response. Receptor subtype distribution explains organ selectivity and many adverse effects of drugs.

A harmful or unintended response to a medicine at normal doses. It may be predictable and dose-related or unpredictable and idiosyncratic, and it requires assessment and reporting.

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.

A national spontaneous reporting scheme through which health professionals and patients report suspected adverse drug reactions to the regulatory authority. Reports feed into signal detection and safety updates.

A structured questionnaire used to assess the probability that a drug caused an observed adverse event. Scores classify causality as doubtful, possible, probable, or definite.

Any preventable event that may cause or lead to inappropriate medication use or patient harm. It includes prescribing, dispensing, administration, and monitoring failures, and is distinct from an adverse reaction.

Medication names that appear or sound similar and are easily confused, contributing to wrong-drug errors. Tall-man lettering, separated storage, and read-back verification reduce such risks.

A lawful written, electronic, or verbal order from an authorized prescriber for a medicine. It must contain required elements such as patient, drug, strength, directions, and prescriber details.

The professional process of reviewing an order, preparing, labeling, and supplying a medicine with appropriate advice. It includes accuracy checks and counseling, not merely handing over the product.

A medicine subject to special legal controls because of abuse or dependence potential. Rules govern prescribing authority, validity, record keeping, secure storage, and repeat supply.

Prescribing or supplying a licensed medicine outside its approved indications, dose, or population. It may be clinically justified but carries different legal and evidentiary considerations.

A patient's voluntary agreement to a treatment or procedure after receiving and understanding relevant information about benefits, risks, and alternatives. It is central to ethical pharmacy practice.

A structured two-way discussion in which the pharmacist explains how to use a medicine, expected effects, precautions, and when to seek help, checking the patient's understanding.

A person's ability to obtain, understand, and use health information to make decisions. Low literacy requires plain language, visual aids, and teach-back confirmation during counseling.

A counseling technique in which the patient restates instructions in their own words, allowing the pharmacist to confirm understanding and correct misunderstandings without blame.

A calculation method for mixing two preparations of different strengths to obtain a desired intermediate strength. It uses proportional parts and is common in compounding and dilution problems.

A way of expressing strength as parts per hundred, with meaning depending on the basis: weight-in-volume, weight-in-weight, or volume-in-volume. Basis must be clarified before calculating a dose.

Extemporaneous preparation of a medicine tailored to a patient's needs, such as a liquid form for a child. It requires documented formulas, quality controls, and stability considerations.

The study of how genetic variation affects drug response, including metabolism, efficacy, and toxicity risk. Testing can guide drug or dose selection for selected therapies.

The study of drug use and effects in large populations, using observational methods to estimate risks and benefits. It supports post-marketing safety decisions and public health policy.

The extent to which a patient takes medicines as agreed with the prescriber. Barriers include cost, side effects, complexity, and beliefs, and interventions should address the specific cause.

A patient-centered practice model in which the pharmacist accepts responsibility for optimizing drug therapy and identifying, resolving, and preventing drug-related problems.