CPI Pharmacology & Medication Management 2 — Questions and Answers
Question 1: In a clinical trial, a participant develops QT prolongation after starting a study drug. Which pharmacological mechanism most commonly causes this adverse effect?
- Inhibition of hERG potassium channels (Correct answer)
- Activation of sodium-calcium exchangers
- Blockade of L-type calcium channels
- Inhibition of HCN pacemaker channels
Correct answer: Inhibition of hERG potassium channels
hERG (IKr) potassium channel inhibition delays cardiac repolarization, prolonging the QT interval and increasing arrhythmia risk.
Question 2: A Phase I trial is assessing drug X metabolism. CYP2D6 poor metabolizers show 4-fold higher AUC compared to extensive metabolizers. What is the most appropriate dose adjustment strategy?
- Reduce dose by 75% in poor metabolizers (Correct answer)
- Increase dose by 75% in poor metabolizers
- No adjustment needed as efficacy is unaffected
- Exclude poor metabolizers from the trial entirely
Correct answer: Reduce dose by 75% in poor metabolizers
A 4-fold AUC increase in poor metabolizers indicates significantly reduced clearance, requiring dose reduction to avoid toxicity.
Question 3: During a trial of an oral anticoagulant, a participant's renal function declines (CrCl drops from 65 to 28 mL/min). What pharmacokinetic parameter is most directly affected?
- Renal clearance and elimination half-life (Correct answer)
- Volume of distribution and bioavailability
- Protein binding and hepatic extraction ratio
- First-pass metabolism and Cmax
Correct answer: Renal clearance and elimination half-life
Renal clearance decreases proportionally with GFR decline, prolonging elimination half-life for renally eliminated drugs.
Question 4: A study drug is a potent inhibitor of P-glycoprotein (P-gp). A participant is concurrently taking digoxin. What is the expected drug-drug interaction?
- Increased digoxin plasma concentrations (Correct answer)
- Decreased digoxin plasma concentrations
- No change in digoxin levels
- Accelerated digoxin renal excretion
Correct answer: Increased digoxin plasma concentrations
P-gp normally effluxes digoxin from enterocytes and renal tubular cells; P-gp inhibition increases digoxin absorption and reduces its secretion, raising plasma levels.
Question 5: A participant in an analgesic trial develops respiratory depression 6 hours after the last dose of the study opioid. The drug's half-life is 18 hours. What principle best explains this delayed toxicity?
- Drug accumulation over multiple half-lives (Correct answer)
- Active metabolite formation
- Enterohepatic recirculation
- pH-dependent renal reabsorption
Correct answer: Drug accumulation over multiple half-lives
Drugs with long half-lives accumulate with repeated dosing, reaching toxic concentrations only after several half-lives of administration.
Question 6: In a clinical trial, the investigator must report a serious unexpected suspected adverse reaction (SUSAR). Which feature specifically makes an adverse event a SUSAR?
- Serious, unexpected, and reasonably related to the IMP (Correct answer)
- Any serious adverse event occurring during the trial
- Any event not listed in the protocol
- An adverse event requiring hospitalization only
Correct answer: Serious, unexpected, and reasonably related to the IMP
A SUSAR requires all three criteria: the event is serious, not consistent with the reference safety information, and has a plausible causal relationship to the investigational medicinal product.
Question 7: A new antibiotic study drug demonstrates a post-antibiotic effect (PAE). What does this mean for dosing strategy in the clinical trial?
- The drug may be effective with less frequent dosing intervals (Correct answer)
- The drug must be given more frequently to maintain efficacy
- The drug's efficacy depends solely on peak concentration
- PAE indicates the drug is bacteriostatic rather than bactericidal
Correct answer: The drug may be effective with less frequent dosing intervals
PAE refers to continued bacterial suppression after drug concentrations fall below MIC, allowing for extended dosing intervals without loss of efficacy.
CPI Pharmacology & Medication Management 2
In a clinical trial, a participant develops QT prolongation after starting a study drug.
Which pharmacological mechanism most commonly causes this adverse effect?