Master of Pharmacy: Pharmacokinetics and Pharmacodynamics Flashcards
7 cards from real MPharm Master 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 Master of Pharmacy: Pharmacokinetics and Pharmacodynamics flashcards as text
The Emax model in pharmacodynamics relates drug effect to concentration. At concentrations much lower than EC50, the relationship approximates:
Answer: A linear relationship between concentration and effect
When C << EC50, the Emax equation simplifies to E ≈ Emax × C/EC50, which is a linear approximation.
Population pharmacokinetics differs from classical PK analysis primarily in that it:
Answer: Quantifies between-subject variability and identifies covariates explaining it
Population PK uses nonlinear mixed-effects modeling (e.g., NONMEM) to characterize PK parameters and their variability across a patient population with sparse sampling.
Which statement about drug protein binding is correct regarding pharmacokinetic implications?
Answer: Only the unbound fraction is available for distribution, metabolism, and receptor interaction
Only free (unbound) drug crosses membranes, interacts with receptors, and is available for metabolism and elimination.
A patient with chronic kidney disease (CKD) stage 4 is prescribed a drug that is 80% renally eliminated unchanged. The expected outcome without dose adjustment is:
Answer: Drug accumulation and potential toxicity due to reduced elimination
CKD severely reduces renal clearance of drugs eliminated unchanged, causing accumulation and elevated plasma concentrations that may lead to toxicity.
Mechanism-based (irreversible) enzyme inhibition differs from reversible inhibition because it:
Answer: Requires new enzyme synthesis for recovery of metabolic capacity
Mechanism-based inhibitors covalently inactivate the enzyme, so metabolic function is only restored when new enzyme protein is synthesized.
The concept of therapeutic index (TI) is best defined as:
Answer: The ratio of the median toxic dose (TD50) to the median effective dose (ED50)
The therapeutic index is TD50/ED50; drugs with a narrow TI require careful monitoring because toxic and therapeutic doses are close.
Pharmacodynamic tolerance that develops due to reduced receptor density following prolonged agonist exposure is specifically called:
Answer: Down-regulation (receptor desensitization)
Prolonged agonist stimulation causes receptor internalization and degradation (down-regulation), reducing receptor number and attenuating drug response.