Pharmacokinetics Questions and Answers | Latest Version | 2025/2026 | Correct & Verified

Pharmacokinetics Questions and Answers | Latest Version | 2025/2026 | Correct & Verified What is pharmacokinetics? The study of how the body absorbs, distributes, metabolizes, and excretes drugs What does the term absorption mean in pharmacokinetics? The process by which a drug moves from its site of administration into the bloodstream Which factor can affect the rate of drug absorption? The drug’s formulation, route of administration, and gastrointestinal motility What is bioavailability? The proportion of a drug that enters the systemic circulation and is available for therapeutic effect How does first-pass metabolism affect oral drugs? 2 It reduces bioavailability by metabolizing a portion of the drug in the liver before reaching systemic circulation What is drug distribution? The process of a drug moving from the bloodstream to tissues and organs Which factor can influence drug distribution? Blood flow, protein binding, and tissue permeability What is the role of plasma proteins in drug distribution? They bind drugs and affect the free, active concentration available to tissues What is volume of distribution (Vd)? A theoretical volume that relates the amount of drug in the body to its concentration in the blood How is drug metabolism defined? 3 The chemical alteration of a drug in the body, usually by liver enzymes, to facilitate excretion What is the main organ responsible for drug metabolism? The liver What is a prodrug? A drug administered in an inactive form that becomes active after metabolism Which phase of metabolism makes drugs more water-soluble? Phase I and Phase II reactions (oxidation, reduction, conjugation) What is drug excretion? The removal of drugs or their metabolites from the body, mainly via urine or bile Which organ is primarily responsible for drug excretion? The kidneys 4 How does renal impairment affect drug excretion? It can decrease drug clearance and increase the risk of toxicity What is half-life of a drug? The time required for the plasma concentration of a drug to reduce by half Why is half-life important in dosing schedules? It helps determine how often a drug should be administered to maintain therapeutic levels What is steady-state concentration? The point at which drug intake equals drug elimination, maintaining a consistent blood concentration How many half-lives are typically needed to reach steady-state?