Biopharmaceutics & Pharmacokinetics Flashcards
7 cards from real B.Pharm. Bachelor of Pharmacy practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biopharmaceutics & Pharmacokinetics flashcards as text
The therapeutic index (TI) of a drug is defined as the ratio of:
Answer: LD50 to ED50
The therapeutic index is calculated as LD50/ED50; a higher TI indicates a greater margin of safety between the lethal dose and the effective dose of a drug.
Zero-order kinetics means that the rate of drug elimination is:
Answer: Constant and independent of plasma drug concentration
In zero-order kinetics, a constant amount of drug is eliminated per unit time regardless of plasma concentration, typically occurring when elimination mechanisms are saturated (e.g., ethanol, phenytoin at high doses).
The absorption rate constant (Ka) is used to describe:
Answer: The speed at which a drug is absorbed from the site of administration into systemic circulation
Ka (absorption rate constant) quantifies how quickly a drug moves from its site of administration into the systemic circulation, influencing Tmax and Cmax values.
The Area Under the Curve (AUC) in pharmacokinetics represents:
Answer: Total drug exposure over time
AUC (Area Under the plasma concentration-time Curve) represents the total drug exposure over time and is directly proportional to the total amount of drug that reaches systemic circulation.
Highly plasma protein-bound drugs have a characteristically:
Answer: Small volume of distribution and prolonged half-life
Drugs extensively bound to plasma proteins remain in the vascular compartment (small Vd), are protected from metabolism/excretion, and have a prolonged half-life due to reduced free drug available for elimination.
Enterohepatic circulation involves the recycling of drugs or metabolites through the:
Answer: Liver, bile, intestine, and portal vein
Enterohepatic circulation occurs when a drug or its conjugated metabolite is excreted in bile, deconjugated by gut bacteria in the intestine, reabsorbed, and returned to the liver via the portal vein, prolonging drug action.
A drug with a volume of distribution (Vd) of 200 L in a 70 kg person suggests the drug is:
Answer: Extensively distributed into peripheral tissues
A large Vd (e.g., 200 L far exceeds plasma volume of ~3 L and total body water of ~42 L) indicates extensive distribution into peripheral tissues and/or intracellular compartments.